Monitoring Selected National HIV Prevention and Care Objectives By Using HIV Surveillance Data United States and 6 Dependent Areas, 2019: Technical Notes

A. Surveillance of HIV Infection Overview

This report includes data reported to CDC through December 31, 2020, from all 50 states, the District of Columbia, and 6 U.S. dependent areas (American Samoa, Guam, the Northern Mariana Islands, Puerto Rico, the Republic of Palau, and the U.S. Virgin Islands). After the removal of personally identifiable information, data were submitted to CDC.

Please use caution when interpreting data on diagnosed HIV infection. HIV surveillance data on persons with diagnosed HIV infection may not be representative of all persons with HIV because not all infected persons have been (1) tested or (2) tested at a time when the infection could be detected and diagnosed. Also, some states offer anonymous HIV testing; the results of anonymous tests are not reported to the confidential name-based HIV registries of state and local health departments. Therefore, reports of confidential test results may not represent all persons who tested positive for HIV infection.

Please use caution when interpreting laboratory data for persons with diagnosed HIV infection. Laboratory data presented in this report are from 45 jurisdictions (44 states and the District of Columbia) that reported complete CD4+ T-lymphocyte (CD4) and viral load test results to CDC as of December 31, 2020. Data from these 45 jurisdictions represent 89% of all persons aged ≥13 years living with diagnosed HIV infection at year-end 2019 in the United States and are therefore not representative of data on all persons living with diagnosed HIV infection in the United States.

B. Stages of HIV Infection

Both the 2008 and 2014 HIV case definitions were used to classify HIV infection among adults and adolescents and among children [13, 14]. In the following lists, some bulleted items are paraphrases, not quotations, from the published surveillance case definitions. The intention is to emphasize the differences between the 2008 and 2014 case definitions.

B1. 2008 Case Definition

The 2008 case definition was used to classify cases diagnosed through 2013. For adults and adolescents, this definition incorporates an HIV infection staging system that includes AIDS (HIV infection, stage 3). The 2008 stages of HIV infection are defined as follows:

• HIV infection, stage 1: No AIDS-defining condition and either a CD4 count of ≥500 cells/µL or a CD4 percentage of total lymphocytes of ≥29.
• HIV infection, stage 2: No AIDS-defining condition and either a CD4 count of 200–499 cells/µL or a CD4 percentage of total lymphocytes of 14–28.
• HIV infection, stage 3 (AIDS): Documentation of an AIDS-defining condition or either a CD4 count of <200 cells/µL or a CD4 percentage of total lymphocytes of <14. Documentation of an AIDS-defining condition supersedes a CD4 count or percentage that would not, by itself, be the basis for a stage 3 (AIDS) classification.
• HIV infection, stage unknown: No reported information on AIDS-defining conditions and no information available on CD4 count or percentage.

B2. 2014 Case Definition

In 2014, the HIV surveillance case definition was revised to adapt to changes in diagnostic criteria [13]; the laboratory criteria for defining a confirmed case of HIV infection were changed to accommodate multitest algorithms that did not include previously required tests (e.g., Western blot). New to the case definition is the inclusion of criteria for differentiating HIV-1 and HIV-2 infections and for recognizing early HIV infection (stage 0), during which viral loads may be high enough and CD4 T-lymphocyte counts low enough to be misclassified as stage 3 (AIDS). The 2014 case definition was used to classify cases diagnosed in 2014 and later. It is similar to the 2008 case definition except for the following:

• inclusion of criteria for stage 0,
• the inclusion of CD4 testing criteria for stage 3 in children, and
• changes in the cutoffs for CD4 percentage of total lymphocytes used for classification of stages 1 and 2 in persons aged ≥6 years.

The stages of HIV infection in the 2014 case definition are based on age specific CD4 counts or percentages of total lymphocytes and are defined as follows:

• HIV infection, stage 0: First positive HIV test result within 6 months after a negative HIV test result. The stage remains stage 0 until 6 months after the first positive test result. After 6 months, the stage may be classified as 1, 2, 3, or unknown if based on a CD4 test result or the diagnosis of an AIDS-defining condition. The diagnosis of an AIDS-defining condition or a low CD4 test result before the 6 months have elapsed does not change the stage from stage 0 to stage 3.
• HIV infection, stages 1, 2, and 3: Documentation of an AIDS-defining OI (excluding stage 0 as described above) is stage 3. Otherwise, the stage is determined by the lowest CD4 lymphocyte test result:
  • Stage 1—CD4 lymphocyte count of ≥500 or a CD4 percentage of total lymphocytes of ≥26
  • Stage 2—CD4 lymphocyte count of 200–499 or a CD4 percentage of total lymphocytes of 14–25
  • Stage 3—CD4 lymphocyte count of <200 or a CD4 percentage of total lymphocytes of <14 or documentation of an AIDS-defining condition.
• HIV infection, stage unknown: No reported information on AIDS-defining conditions and no information available on CD4 count or percentage.

The transition to CD4 lymphocyte–based criteria for stage 3 (AIDS) among children has resulted in an increase in the number of annual stage 3 (AIDS) classifications among pediatric cases diagnosed after 2013. Before the implementation of the 2014 revised case definition, an OI diagnosis was required for a pediatric case to meet the criteria for stage 3 classification.

C. Areas with Complete Laboratory Reporting

As of December 31, 2020, 45 jurisdictions (44 states and the District of Columbia) had met the following criteria for the collection and reporting of CD4 and viral load test results:

• The jurisdiction’s laws/regulations required the reporting of all levels of CD4 and viral load results to the state or local health department (Table 12).
• Laboratories that perform HIV-related testing for the jurisdiction had reported a minimum of 95% of HIV-related test results to the state or local health department.
• By December 31, 2020, the jurisdiction had reported (to CDC) at least 95% of all CD4 and viral load test results received from January 2018 through September 2020.

The 44 states are Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Illinois, Indiana, Iowa, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Washington, West Virginia, Wisconsin and Wyoming. Data from these states and the District of Columbia were used to populate Tables 1a–d, 2a–d, 3a–d, and 4a–b.

D. Tabulation and Presentation of Data

The data in this report include information received by CDC through December 31, 2020. The data are organized into 2 sections: National Profile and Special Focus Profiles. For both the National Profile and Special Focus Profiles, figures are presented.

1. Tables 1a–d present data for stage of disease at time of diagnosis during 2019.
2. Tables 2a–d present data for on linkage to HIV medical care were based on persons whose infection was diagnosed during 2019 and who resided in any of the 45 jurisdictions at the time of diagnosis; and viral suppression within 6 months of diagnosis was measured for persons whose infection was diagnosed during 2019.
3. Tables 3a–d present data on receipt of and retention in HIV medical care were based on persons whose infection was diagnosed by year-end 2018, who resided in any of the 45 jurisdictions as of their most recent known address, and who were alive at year-end 2019.
4. Tables 3c–4b present data for viral suppression among persons whose infection was diagnosed by year-end 2018, who resided in any of the 45 jurisdictions as of their most recent known address during 2019, and who were alive at year-end 2019.
5. Table 5 presents data for prevalence-based HIV care continuum for persons living with HIV infection (diagnosed or undiagnosed) at year-end 2019.
6. Tables 6a–d present data for stage 3 (AIDS) at time of HIV diagnosis from 2015–2019.
7. Tables 7a–f present data of deaths for persons with diagnosed HIV infection and of persons with infection ever classified as stage 3 (AIDS) from 2015–2019.
8. Tables 8a–f present survival for > 3 years for persons with diagnosed HIV infection and for persons whose infection had ever been classified as stage 3 (AIDS) from 2011–2016.
9. Tables 9a/b presents PrEP data.
10. Tables 10a/b presents data for infants with infection attributed to perinatal transmission from 2015–2019.

D1. Definitions and Data Specifications

D1.1 Stage 3 (AIDS) and stage of disease at time of diagnosis of HIV Infection

Data on persons with HIV infection, stage 3 (AIDS), include persons whose infection has ever been classified as stage 3 (AIDS). These data do not necessarily represent the current stage of disease.

Because a complete assessment of stage of disease at time of HIV diagnosis relies on complete laboratory data (all CD4 values) so that earlier stages of disease (stage 0, 1, or 2) can be assessed, stage of disease at time of diagnosis was calculated for the 45 jurisdictions that reported complete laboratory data (Tables 1a/b).

Information on stage 3 (AIDS) is available for all 50 states, the District of Columbia, and 6 U.S. dependent areas, even when not all CD4 values are reportable; therefore, stage 3 (AIDS) at time of HIV diagnosis was calculated for persons in all areas (Tables 6a–d).

Stage of disease at time of diagnosis (i.e., HIV infection, stage 0, 1, 2, 3 [AIDS], or unknown; Tables 1a–d) and stage 3 (AIDS) at time of HIV diagnosis (Tables 6a–d) were determined by using the first CD4 test result or documentation of an AIDS-defining condition ≤3 months after the HIV diagnosis date during 2019, unless documentation indicated disease stage 0. If ≥2 events occurred during the same month and could thus qualify as “first,” the following conditions were applied:

• If an AIDS-defining condition was documented, the AIDS-defining condition was used; if a CD4 count or a CD4 percentage had been reported and an AIDS-defining condition was documented, the AIDS-defining condition was used.
• If an AIDS-defining condition was not documented, but a CD4 count and a CD4 percentage had been reported, the CD4 count was used.
• If an AIDS-defining condition was not documented, but >1 CD4 count had been reported, the lowest CD4 count (indicative of the most severe disease state) was used.
• If an AIDS-defining condition was not documented and a CD4 count had not been reported, but a CD4 percentage had been reported, the CD4 percentage was used. If >1 CD4 percentage was reported, the lowest CD4 percentage (indicative of the most severe disease state) was used.

For stage of disease at time of diagnosis, infections were classified as “stage unknown” if the month of HIV diagnosis was missing, or if, ≤3 months after HIV diagnosis, neither a CD4 count nor a CD4 percentage had been determined and no AIDS-defining condition was documented.

D1.2 Linkage to, and Receipt of, HIV Medical Care

National guidelines for the clinical care and treatment of adults and adolescents living with HIV [15] recommend initiation of treatment immediately at time of HIV diagnosis regardless of viral load or CD4 count. Initiation of treatment immediately (or as soon as possible after HIV diagnosis) is to increase treatment uptake and linkage to care, decrease the time to viral suppression for individual patients, and improve the rate of viral suppression among persons with HIV. CD4 and viral load testing is still recommended for use in clinical practice to direct the course of treatment and assess effectiveness of treatment.

For special patient populations with HIV such as transgender and nonbinary persons, knowledge of their unique care and service needs are critical to reduce barriers to engagement in care, improve health, and reduce the risk of HIV transmission to sexual partners. For transgender males and nonbinary persons of childbearing potential, a pregnancy test should be performed prior to ART initiation and selection of treatment should be based on their clinical history and pregnancy potential needs. Otherwise, ART-naïve patients who are pregnant should be started on treatment based on perinatal guidelines and counseled during pregnancy for their health and to prevent HIV transmission to the fetus.

For all transgender and nonbinary persons, clinical outcomes, potential adverse effects, treatment goals, and the patient’s current hormone levels should be considered when determining the appropriate doses of hormone and androgen blockers. Clinical treatment effects and hormone levels should be routinely monitored with appropriate titrations of estradiol, testosterone, or androgen blockers, as needed. Interpretation of laboratory results is dependent on patient physiology and the specific test being performed as recommended in the guidelines from the Center of Excellence for Transgender Health.

For patients who are not taking antiretroviral therapy (ART), CD4 count should be monitored every 3–6 months. For virally suppressed patients who have taken ART for ≤2 years, viral load testing is recommended every 3 to 4 months or as clinically indicated to confirm continuous viral suppression. For virally suppressed patients who have taken ART for >2 years, viral load testing at 6-month intervals may be considered. For virally suppressed patients with treatment modifications due to drug toxicities or regimen simplification, viral load testing is recommended 4 to 8 weeks after treatment modification to confirm regimen effectiveness. For virally suppressed patients whose CD4 counts have consistently ranged from 300 to 500 cells/µL for ≥2 years, annual monitoring of CD4 count is recommended. For virally suppressed patients whose CD4 counts have consistently been >500 cells/µL for ≥2 years, continued CD4 monitoring is optional.

Frequent monitoring of CD4 count, especially among persons with higher counts (>300 cells/µL) and consistently suppressed viral loads, is generally not required for patient management. However, if clinically indicated, the CD4 count should be monitored more frequently (e.g., when changes in a patient’s clinical status decrease CD4 count and thus prompt the need for prophylaxis for opportunistic infection).

The data on linkage to HIV medical care were based on persons whose infection was diagnosed during 2019 and who resided in any of the 45 jurisdictions at the time of diagnosis (Tables 2a–d). Linkage to HIV medical care within 1 month after HIV diagnosis was measured by documentation of ≥1 CD4 (count or percentage) or viral load tests performed ≤ 1 month after HIV diagnosis, including tests performed on the same date as the date of diagnosis. Linkage to HIV medical care within 3 months after HIV diagnosis was measured by documentation of ≥1 CD4 (count or percentage) or viral load tests performed ≤ 3 months after HIV diagnosis, including tests performed on the same date as the date of diagnosis.

The data on receipt of HIV medical care were based on persons whose infection was diagnosed by year-end 2018, who resided in any of the 45 jurisdictions as of their most recent known address, and who were alive at year-end 2019 (Tables 3a–d). Receipt of any HIV medical care was measured by documentation of ≥1 CD4 or viral load tests performed during 2019. Retention in care (receipt of continuous HIV medical care) was measured by documentation of ≥2 CD4 or viral load tests performed ≥3 months apart during 2019.

For analyses of linkage to, and retention in, care, the month and the year of the earliest HIV-positive test result reported to the surveillance system were used to determine the diagnosis date. Test results were excluded if the month of the sample collection was missing. For linkage to care, data were excluded if the month of diagnosis was missing. For receipt of care, retention in care, and viral suppression, data were excluded if the date of death (where applicable) occurred before the year of interest or was missing.

D1.3 Viral Suppression

Viral suppression was measured among persons whose infection was diagnosed by year-end 2018, who resided in any of the 45 jurisdictions as of their most recent known address during 2019, and who were alive at year-end 2019 (Tables 4a/b). Viral suppression was defined as a viral load result of <200 copies/mL at the most recent viral load test. The cutoff value of <200 copies/ mL was based on the following definition of virologic failure: viral load of ≥ 200 copies/mL. If multiple viral load tests were performed during the same month and could thus qualify as “most recent,” the highest viral load (most severe) was selected. If the numerical result was missing or the result was a logarithmic value, the interpretation of the result (e.g., below limit) was used to determine viral suppression. Virologic failure may indicate lack of adherence to ART.

Viral suppression within 6 months of diagnosis was measured for persons whose infection was diagnosed during 2019 and who resided in any of the 45 jurisdictions at the time of diagnosis (Tables 2a-d). Viral suppression was defined as a viral load result of <200 copies/mL at any viral load test within 6 months of an HIV diagnosis made during 2019.

D1.4 Deaths

Persons whose HIV infections are reported to the National HIV Surveillance System (NHSS) are assumed to be alive unless their deaths have been reported to CDC. Death data were based on deaths of persons with diagnosed HIV infection and of persons with infection ever classified as stage 3 (AIDS), regardless of the cause of death. Jurisdiction-level data were based on area of residence at death. If information on residence at death was not available, the state where a person’s death occurred was used. Data for the year 2019 are preliminary and based on death data received by CDC through December 2020.

Monitoring receipt of HIV medical care, retention in HIV medical care, viral suppression at most recent test, deaths and survival of persons with diagnosed HIV infection, and the prevalence-based HIV care continuum is dependent upon complete death ascertainment conducted by HIV surveillance programs for reporting to CDC. Due to incomplete reporting of deaths for the year 2019, death data for Kansas, Massachusetts, Mississippi, North Dakota, Nevada, Vermont, and the U.S. Virgin Islands should be interpreted with caution. Please use caution when interpreting trend data: the numbers for the most recent year are subject to uncertainty.

D1.5 Survival Analyses

The Kaplan-Meier method was used to estimate the probability of survival (Tables 8a–f) for >3 years (36 months) for persons with diagnosed HIV infection and for persons whose infection had ever been classified as stage 3 (AIDS). To allow ≥3 years from the time of HIV diagnosis to a death date on or before December 31, 2019, tables were limited to data on persons whose diagnosis or stage 3 (AIDS) classification was made during 2011–2016. The results of survival analyses for areas with <100 diagnoses per year (i.e., <600 during the 6-year period) were unstable and therefore are not presented in this report.

D1.6 Perinatally Acquired HIV Infection

Table 10a presents data for infants with infection attributed to perinatal transmission and reported to NHSS through December 2020. The data include all persons reported to NHSS with infection attributed to perinatal exposure, regardless of place of birth. Table 10b presents a subset of data from Table 10a: the data include only the persons whose case record denoted the United States as place of birth or residence at birth. The data on persons with perinatally acquired infection that are presented in Table 10b do not include persons who were born in a U.S. dependent area or a foreign country or whose residence at birth was unknown or missing from the case record.

D1.7 Preexposure Prophylaxis (PrEP) Coverage

PrEP coverage, reported as a percentage, is defined as the number of persons aged ≥16 years classified as having been prescribed PrEP during the specified year divided by the estimated number of persons aged ≥16 years who had indications for PrEP during the specified year (Tables 9a/b, A5, S7a/b).

Number of persons prescribed, which is reported as a case count, is defined as the number of persons aged ≥16 years classified as having been prescribed PrEP during the specified year.

PrEP coverage is an EHE indicator that is not a reportable disease or condition and is not reported to NHSS. Multiple data sources, described below, are used to calculate PrEP coverage. Please use caution when interpreting PrEP data. Different data sources were used in the numerator and denominator to calculate PrEP coverage.

D1.7.1 Persons prescribed PrEP

National pharmacy data from the IQVIA Real-World Longitudinal Prescriptions database (hereafter, IQVIA database) are used to classify persons aged ≥16 years who have been prescribed PrEP in the specific year. The IQVIA database captures prescriptions from all payers and represents approximately 92% of all prescriptions from retail pharmacies and 60%–86% from mail-order outlets in the United States. The database does not include prescriptions from some closed health care systems that do not make their prescription data available to IQVIA. Therefore, these are minimum estimates of PrEP coverage. The database includes antiretroviral drugs prescribed, demographic variables of persons to whom the drugs were prescribed, and medical claims for these persons. IQVIA acquires medical claims and race/ethnicity data from various sources, including ambulatory, hospital, and consumer databases, and links these data to persons in the prescription data- base. The annual number of persons classified as having been prescribed PrEP was based on a validated algorithm that discerns whether tenofovir disoproxil fumarate and emtricitabine (TDF/FTC) were prescribed for PrEP after excluding prescriptions for HIV treatment, hepatitis B treatment, or HIV postexposure prophylaxis [16, 17]. Tenofovir alafenamide and emtricitabine (TAF/FTC) was approved as an alternative drug for PrEP by the U.S. Food and Drug Administration (FDA) in October 2019. Starting in 2019, TAF/FTC was included in the algorithm to classify the number of persons prescribed PrEP.

The number of persons classified as having been prescribed PrEP is reported by sex, age group, and race/ethnicity. Transmission category data are not available in the IQVIA database and race/ethnicity data are available for < 40% of persons with PrEP prescriptions. Please use caution when interpreting PrEP data by race/ethnicity. Race/ethnicity categories available in the IQVIA data include White, Black, Hispanic/Latino, and other. The number of persons prescribed PrEP for each racial/ethnic group presented in this report was extrapolated by applying the racial/ethnic distribution of known records to those for which data on race/ethnicity were unknown.

D1.7.2 Preexposure Prophylaxis (PrEP) Coverage—Geographic designations

In the IQVIA database, a person’s location is reported as a 3-digit ZIP code prefix (hereafter, ZIP3) assigned by the U.S. Postal Service. To estimate the number of persons prescribed PrEP at the state or county level, a probability-based approach used to crosswalk between ZIP3s and states/counties by using the most recent data from (a) U.S Census Bureau’s American Community Survey (ACS) 5-year estimates by ZIP code Tabulate Area (ZCTA) [18], and (b) the U.S. Department of Housing and Urban Development’s ZIP Code Crosswalk Files [19]. Because of reliability concerns, subnational estimates of <50 are not included in this report.

D1.7.3 Persons with indications for PrEP

ACS and U.S. Census Bureau files were used to estimate the number of MSM (men who have sex with men) in a jurisdiction [20, 21]. Next, behavioral data from the National Health and Nutrition Examination Survey (NHANES) were used to estimate the proportion of HIV-negative MSM with indications for PrEP [22]. For 2018 denominator, this proportion was updated with the recent NHANES data.

The number of HIV-negative MSM with indications for PrEP was multiplied by the ratio of percentage of HIV diagnoses during the specified year attributed to other major transmission risk groups compared to the percentage among MSM in a given state or county. The estimated number of persons with indications for PrEP in the 3 major transmission risk groups (MSM, heterosexuals, PWID [persons who inject drugs]) in each jurisdiction were then summed to yield a state or county-specific estimate. State estimates were then summed for a national total of persons with indications for PrEP [23]. Jurisdictional estimates were rounded to the nearest 10. Beginning in 2017, methods were adjusted to provide the estimated number of persons of other races/ethnicities (including Asian persons and persons in other racial/ethnic groups), in addition to Black or African American, Hispanic or Latino, and White persons. Also beginning in 2017, an adjustment was applied to calculate an estimated number of persons with PrEP indications in counties with suppressed data for the number of HIV diagnoses in some transmission risk groups, age groups, or race/ethnicity groups.

The tables included in this report provide updated data on PrEP coverage for the years 2017 and 2018 and preliminary data for the year 2019 and for the year 2020 (from January through September) using the IQVIA data reported through September 2020. The data sources used to estimate the number of persons with indications for PrEP have different schedules of availability. Consequently, the availability of a denominator lags the availability of a numerator by approximately 1 year. For this release of the 2019 Monitoring Report, 2017 denominators were used for 2017 PrEP coverage data; 2018 denominators were used for 2018, 2019, and 2020 PrEP coverage data. In addition to being preliminary, data for the year 2020 should be interpreted with awareness of the impact of the COVID-19 pandemic on filling PrEP prescriptions in state/local jurisdictions.

D2. Rates

Rates per 100,000 population were calculated for (1) the numbers of diagnoses of HIV infection, (2) the numbers of deaths of persons with diagnosed HIV infection, and (3) the numbers of persons living with diagnosed HIV infection. The standard used for reporting trends in numbers and percentages is an increase or a decrease of 5% or more during the specified time frame (e.g., when comparing 2015 and 2019). The exceptions to this standard are where population sizes or numbers were small (i.e., less than 12) or percentages were based on small numbers or population sizes.

The population denominators used to compute the rates for the 50 states, the District of Columbia, and Puerto Rico were based on the Vintage 2019 postcensal estimates file (for years 2015–2019) from the U.S. Census Bureau [24]. The population denominators for American Samoa, Guam, the Northern Mariana Islands, the Republic of Palau, and the U.S. Virgin Islands were based on estimates and projections from the U.S. Census Bureau’s International Data Base [25]. Each rate was calculated by dividing the total number of diagnoses (or deaths or prevalence) for the calendar year by the population for that calendar year and then multiplying the result by 100,000. The denominators used for calculating the rates specific to age, sex at birth, and race/ethnicity were computed by applying the appropriate vintage estimates for age, sex at birth, and race/ethnicity for the 50 states and the District of Columbia [24]. The same method was used to calculate the denominators for Puerto Rico, with the exception of race/ethnicity estimates; these data are not available for Puerto Rico (see next paragraph). For the other 5 U.S. dependent areas, estimates from the U.S. Census Bureau’s International Data Base were used for age- and sex-specific population denominators [25].

CDC currently does not provide subpopulation rates by race/ethnicity for the 6 U.S. dependent areas because the U.S. Census Bureau does not collect information from all dependent areas. Rates for gender and transmission categories are not provided in this report because of the absence of denominator data from the U.S. Census Bureau, the source of data used for calculating all rates in this report.

In the tables displaying data on perinatally acquired HIV infection (Tables 10a/b), rates were calculated per 100,000 live births [26]. Prevalence trends and data reflect persons living with diagnosed HIV infection, regardless of stage of disease, (Figures 9, 10, 36, and 37; Tables 15a/b–22 and A2) at the end of a given year during 2015–2019. Because of delays in the reporting of deaths, prevalence data are based on a 12-month reporting delay to allow data to be reported to CDC. For tables presenting prevalence data, region or area of residence is based on most recent known address as of the end of the specified year. Data for the year 2019 are preliminary and based on death data received by CDC as of December 31, 2020. Trends through 2019 should be interpreted with caution. Due to incomplete reporting of deaths for the year 2019, prevalence data for Kansas, Massachusetts, Mississippi, Nevada, North Dakota, Vermont, and the U.S. Virgin Islands should be interpreted with caution.

D2.1 Rates of Deaths

In tables displaying data on deaths of persons with diagnosed HIV infection and deaths of persons with infection ever classified as stage 3 (AIDS) (Tables 7a–f), rates were calculated in 3 ways:

• Rates of deaths per 100,000 population: Each rate was calculated by dividing the total number of deaths for the calendar year by the population for that calendar year and then multiplying the result by 100,000.
• Rates of deaths per 1,000 persons living with diagnosed HIV infection or living with infection ever classified as stage 3 (AIDS): Rates were calculated by dividing the reported total number of deaths of persons with diagnosed HIV infection (or with infection classified as stage 3 [AIDS]) during the calendar year by the sum of the number of persons living with a diagnosis of HIV infection (or with infection classified as stage 3 [AIDS]) at the end of the previous calendar year plus the number of diagnoses of HIV infection (or stage 3 [AIDS] classification) during the current calendar year; the result was then multiplied by 1,000.
• Age-adjusted rates of deaths per 100,000 population and per 1,000 persons living with diagnosed HIV infection or living with infection ever classified as stage 3 (AIDS): Tables 7c and 7f include age-adjusted rates by area of residence in addition to crude rates. A standard population distribution was used to adjust death rates per 100,000 population and per 1,000 persons living with diagnosed HIV infection (or with infection ever classified as stage 3 [AIDS]). The age-adjusted rates are rates that would have existed if the age distribution of the designated population and the age distribution of the standard population were the same. The use of the U.S. 2000 standard population in calculating age-adjusted rates was based on recommendations by the National Center for Health Statistics [27, 28].

E. Demographic Information

E1. Age

The designation “adults and adolescents” refers to persons aged 13 years and older, “young adults” refers to persons aged 20–24 years (unless noted otherwise), and “adolescents” refers to persons aged 13–19 years; the designation “children” refers to persons aged less than 13 years.

All tables in this report reflect data on persons aged ≥13 years, with the exception of Tables 9a/b (PrEP coverage) and 10a/b (perinatally acquired HIV infection; birth years 2015–2019).

• Tables 3a–d and 4a/b (receipt of care and viral suppression): age was based on the person’s age at year-end 2018.
• Table 5 (prevalence): age was based on the person’s age at end of the specified year.
• Tables 7a–f (deaths): age was based on the person’s age at the time of death.
• All other tables: age was based on the person’s age at the time of HIV diagnosis.

E2. Sex and Gender

E2.1 Sex at Birth

Sex designations in this report are based on a person’s sex at birth.

E2.2 Gender

Gender identity refers to a person’s internal understanding of their own gender, or gender with which a person identifies. HIV surveillance personnel collect data on gender identity, when available, from sources such as case report forms submitted by health care or HIV testing providers and medical records, or by matching with other health department databases (e.g., Ryan White program data). In May 2012, CDC issued guidance to state and local programs on methods for collecting data on transgender persons and working with transgender-specific data. However, characterization of HIV infection among transgender persons may require supplemental data from special studies. A person’s transgender status in NHSS is determined based on two variables – sex assigned at birth and current gender identity. Both variables are examined, using a two-step approach, to assess transgender status. This method requires the current gender identity variable be explicitly stated, therefore, the number of diagnoses of HIV infection for transgender persons is a minimum count. Although not used in this report, cisgender is a term used to indicate that a person’s sex assigned at birth and current gender identity are the same (i.e., a person assigned male at birth and who currently identifies as a man is a cisgender male).

Categories

• Male: persons assigned “male” sex at birth and current gender identity is not “transgender male-to-female” or “additional gender identity” (current gender identity can be listed as “male,” “female,” “transgender female-to-male,” “unspecified,” or left blank).
• Female: persons assigned “female” sex at birth and current gender identity is not “transgender female-to-male” or “additional gender identity” (current gender identity can be listed as “male,” “female,” “transgender male-to-female,” “unspecified,” or left blank).
• Transgender male-to-female (transgender MTF): persons assigned “male” sex at birth and current gender identity is “transgender male-to-female.”
• Transgender female-to-male (transgender FTM): persons assigned “female” sex at birth and current gender identity is “transgender female-to-male.”
• Additional gender identity (AGI): persons assigned “male” or “female” sex at birth and current gender identity is “additional gender identity.” AGI includes “bigender,” “gender queer,” and “two-spirit.”

E3. Race and Ethnicity

In the Federal Register for October 30, 1997 [29], the Office of Management and Budget (OMB) announced the Revisions to the Standards for the Classification of Federal Data on Race and Ethnicity and mandated implementation by January 1, 2003.  At a minimum, data should be collected for persons in the following race categories:

• American Indian or Alaska Native
• Asian
• Black or African American
• Native Hawaiian or other Pacific Islander
• White

Additionally, systems must be able to retain information when multiple race categories are reported. In addition to data on race, data on 2 categories of ethnicity should be collected:

• Hispanic or Latino
• not Hispanic or Latino

The Asian or Pacific Islander category displayed in annual surveillance reports published prior to the 2007 surveillance report was split into 2 categories: (1) Asian and (2) Native Hawaiian or other Pacific Islander. The Asian category (in tables where footnoted) includes persons categorized as Asian/Pacific Islander (referred to as legacy cases) that were reported before the new race categories were implemented in 2003 (e.g., diagnoses of HIV infection that were reported to CDC before 2003 but that were classified as stage 3 [AIDS] after 2003) and a small percentage of persons that were reported after 2003 but that were reported according to the old race category (Asian/Pacific Islander). In tables of diagnoses of HIV infection during 2015–2019, the Asian category does not include persons categorized as Asian/ Pacific Islander because their diagnosis was made after 2003 and reported to CDC in accordance with OMB’s Revisions to the Standards for the Classification of Federal Data on Race and Ethnicity [29].

This report also presents data for persons for whom multiple race categories are specified (i.e., multiracial). In this report, persons categorized by race were not Hispanic or Latino. The number of persons reported in each race category may, however, include persons whose ethnicity was not reported.

Demographic information for the live birth registry is based on that of the mother [28]. Therefore, Tables 10a/b, which present estimated numbers and rates of perinatally acquired HIV infection, categorize race/ethnicity according to the mother’s race/ethnicity.

Race and ethnicity are not risk factors but are instead markers for many underlying problems of greater relevance to health, including socioeconomic status and cultural behavior-characteristics, which are social and not biological [30, 31]. Racial and ethnic differences in health are more likely to reflect profound differences in people’s experience based on the relatively advantaged or disadvantaged position in society into which they are born [31, 32]. Social determinant of health factors, shaped by income, education, wealth, and socioeconomic conditions, vary systematically by race and ethnicity and are important in explaining differences in health outcomes [32].

E4. Transmission Categories

Transmission category is the term for the classification of cases that summarizes an adult’s or adolescent’s possible HIV risk factors; the summary classification results from selecting, from the presumed hierarchical order of probability, the 1 (single) risk factor most likely to have been responsible for transmission. For surveillance purposes, a diagnosis of HIV infection is counted only once in the hierarchy of transmission categories [33]. Adults or adolescents with >1 reported risk factor for HIV infection are classified in the transmission category listed first in the hierarchy. The exception is men who had sexual contact with other men and injected drugs; this group makes up a separate transmission category.

Hierarchical categories

• Male-to-male sexual contact (MMSC): men who have had sexual contact with men (i.e., homosexual con- tact) and men who have had sexual contact with both men and women (i.e., bisexual contact)
• Injection drug use (IDU): persons who have injected non-prescription drugs
• Male-to-male sexual contact and injection drug use (MMSC-IDU): men who have had sexual contact with other men and injected non-prescription drugs
• Heterosexual contact: persons who have ever had heterosexual contact with a person known to have, or with a risk factor for, HIV infection
• Perinatal: persons infected through perinatal transmission but aged 13 years and older at time of diagnosis of HIV infection. Prevalence data and tables of death data includes persons infected through perinatal transmission but aged 13 years and older during the specified year or at death.
• Other: all other transmission categories (e.g., blood transfusion, hemophilia, risk factor not reported or not identified).

Cases of HIV infection reported without a risk factor listed in the hierarchy of transmission categories are classified as “no identified risk (NIR).” Cases classified as NIR include cases that are being followed up by local health department staff; cases in persons whose risk-factor information is missing because they died, declined to be interviewed, or were lost to follow-up; and cases in persons who were interviewed or for whom other follow-up information was available but for whom no risk factor was identified.

Because a substantial proportion of cases of HIV infection are reported to CDC without an identified risk factor, multiple imputation is used to assign a transmission category to these cases [33]. Multiple imputation is a statistical approach in which each missing transmission category is replaced with a set of plausible values that represent the uncertainty about the true, but missing, value [34].  Each resulting data set containing the plausible values is analyzed by using standard procedures, and the results from these analyses are then combined to produce the final results. In tables displaying transmission categories, multiple imputation was used for adults and adolescents, but not for children (because the number of cases in children is small, missing transmission categories were not imputed). Please use caution when interpreting data for transmission category if no diagnosed cases were reported for a population group. For PrEP data, transmission category data are not available in the IQVIA Real World Data–Longitudinal Prescriptions database (IQVIA database).

F. Geographic Designation

F1. Area of Residence

Data by area of residence reflect the address at the time of stage 3 (AIDS) classification or at the time of diagnosis of HIV infection for Tables 1b, 2b, 6c/d, 7c/f, 8c/f, and A1–A2. In Tables 3b, 4b, and A3–A4, area of residence is based on most recent known address as of December 31 of the specified year. For the death tables (7c/f), area of residence is based on residence at death. When information on residence at death is not available, the state where a person’s death occurred is used. For PrEP data, please see the Preexposure Prophylaxis (PrEP) Coverage—Geographic Designations section.

F2. U.S. Census Regions

Data by region reflect the address at the time of diagnosis of HIV infection for tables that present number of diagnoses (Tables 2a, 6a/b, 8a/b–d/e, S8a–S10a). For the death tables (7a/b–7d/e), region is based on residence at death.

F3. Population Area of Residence

In the Federal Register for June 28, 2010, OMB published revised standards for defining MSAs in federal statistical activities [35]. These standards, which provided for the identification of MSAs in the United States and Puerto Rico, replaced the 2000 standards. The adoption of the new standards was effective as of June 28, 2010. On February 28, 2013, OMB announced new MSA delineations based on the new standards and Census 2010 data [36]. Data by population area of residence reflect the address at the time of stage 3 (AIDS) classification or at the time of diagnosis of HIV infection for Tables 1c, 2a/c, 6a, and 8a/d. Tables 3a/c, 4a, and 7a, population area of residence is based on most recent known address as of December 31 of the specified year. For the death tables (7a/d), population area of residence is based in residence at death.

Other Acknowledgments

We also thank the following staff and contractors of the Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, CDC for their contributions to the report (including graphics) and report website: Michael Friend (editing and desktop publishing), Dawn Smith, Joseph E. Logan, the Prevention Communications Branch: Brittany Petish, Fred Noble (Web & Consumer Services Team), and the Division of Communication Services: Katherine Schlich and Song Choi (Design Team).