Progress Toward Rubella Elimination — World Health Organization European Region, 2005–2019

Immunization Activities

Since 2009, all 53 countries in EUR have included 2 RCV doses as part of a combination vaccine with measles and mumps (MMR)^† or measles, mumps, and varicella (MMRV) vaccine in their routine childhood vaccination schedules. WHO and the United Nations Children’s Fund (UNICEF) estimate annual vaccination coverage for all countries in the region using government-reported administrative coverage data (calculated as the number of doses administered divided by the estimated target population) and vaccination coverage surveys. During 2005–2019, estimated regional coverage with RCV1 was 93%–95%, and in 2019, start highlight30 (57%)end highlight countries achieved ≥95% coverage with the first dose of RCV. In 2005, estimated regional coverage with the second dose of RCV was 76%; and in 2019, second dose coverage had risen to 91% (Table). In 2019, estimated national RCV2 coverage ranged from 76% to 99%. During 2005–2019, >38 million persons received RCV in 71 SIAs conducted in 20 (37%) countries.

Surveillance Activities

Rubella surveillance data are reported monthly to WHO from all EUR countries either directly or via the European Centre for Disease Prevention and Control. As of 2019, 47 (89%) countries reported case-based rubella surveillance data, and six (11%) countries reported aggregate data. Suspected rubella cases are investigated and classified as laboratory-confirmed, epidemiologically linked to a laboratory-confirmed case, clinically compatible, or discarded^§ (6). The WHO European Measles and Rubella Laboratory Network provides laboratory confirmation and genotyping of rubella virus isolates from patients with reported cases (7). Important rubella case-based surveillance performance indicators include 1) the number of suspected cases discarded as nonmeasles or nonrubella (target: ≥2 per 100,000 population); 2) the percentage of case investigations conducted within 48 hours of report (target: ≥80%); 3) the percentage of suspected cases (excluding those that are epidemiologically linked) with an adequate specimen collected within 28 days of rash onset and tested in a WHO-accredited or proficient laboratory (target: ≥80%); and 4) the percentage of cases for which the origin of infection (i.e., the source of the virus) is determined (target: ≥80%) (6). During 2014–2019, the number of EUR countries that met the target for suspected cases discarded as nonrubella at the national level, a measure of surveillance sensitivity, increased from six (11%) in 2014 to 13 (25%) in 2019. From 2014 to 2019, the number of countries achieving the targets for timely investigations of suspected cases and adequate specimen collection increased from 29 (54%) to 34 (64%) and from 11 (21%) to 35 (65%), respectively.

Rubella Incidence and Genotypes

During 2005–2019, annual regional rubella incidence decreased from 234.9 per 1 million population (206,359 cases) in 2005 to 0.67 per 1 million population (620 cases) in 2019 (Table) (Figure 1). The highest rubella incidences in 2019 were in Poland, with 7.7 cases per 1 million population (292 cases) and Ukraine, with 3.1 cases per 1 million population (138 cases). The last documented rubella outbreaks in the region during this period were reported from Romania in 2012 (1,873 cases) and Poland in 2013 (38,548 cases). During 2013–2019, reported rubella cases dropped substantially and occurred as sporadic cases or small clusters, rather than as ongoing transmission or outbreaks. In 2005, 16 CRS cases were reported from seven countries; in 2019, only eight CRS cases were reported from Azerbaijan (one case) and Romania (seven cases) (Table). Genotyping of rubella viruses in the region has been limited; during 2005-2019, EUR reported only 143 rubella virus sequences to the WHO global rubella nucleotide sequence database, providing insufficient data to contribute substantially to determination of elimination of endemic rubella virus transmission nationally or regionally.

Regional Verification Commission and Progress Toward Elimination

The European Regional Verification Commission for Measles and Rubella Elimination (EU-RVC) was established in 2011 to evaluate the status of measles and rubella elimination in EUR countries based on documentation submitted annually by national verification committees (8,9). By the end of 2019, 45 (85%) countries had sustained interruption for ≥36 months and were verified to have eliminated endemic rubella virus transmission (Figure 2).

Discussion

After the 2005 WHO Regional Committee resolution that called for regional elimination of rubella and CRS, EUR has made substantial progress with high reported regional RCV coverage, low rubella incidence, and verification that nearly all countries have achieved elimination of endemic transmission of rubella viruses. EUR countries have shown their commitment to the elimination of measles and rubella and CRS with the Regional Committee resolution in 2005 and reaffirmed that commitment with resolutions in 2010 and 2014 (1–3). All EUR countries have longstanding 2-dose routine RCV immunization schedules that have provided a substantial foundation for establishing population immunity against rubella viruses. Regional rubella coverage with the first and second doses of RCVs has exceeded 93% and 80%, respectively, for the past 10 years. Immunization gaps account for sporadic rubella cases reported in 2019 and have not resulted in confirmed ongoing transmission of rubella viruses.

One of the considerable challenges with verifying rubella elimination has been classifying the large number of clinically compatible rubella cases. In part because rubella is typically a mild disease, a laboratory test is not always performed to confirm a diagnosis, and testing varies considerably across the region according to public health systems, clinical practice, and laboratory capacities. Without a confirmatory laboratory test result, suspected cases are classified as clinically compatible. Increased testing and efficiencies of subnational laboratory networks have contributed to improvements in the surveillance indicators and case classification, but additional efforts are needed.

Rubella population immunity estimates across the region based on longstanding national immunization coverage rates are well above the rubella herd immunity threshold of 83%–86%, which should disrupt chains of transmission and stop or slow the spread of disease (10). However, subnational immunization gaps pose a risk for importation and circulation of rubella viruses. Efforts to eliminate endemic transmission of rubella have benefited substantially from the national and subnational outbreak response immunization campaigns for measles cases with combined measles- and rubella-containing vaccines, particularly for large measles outbreaks during 2017–2020.

Retrospective rubella reviews for the verification process provided an opportunity to focus on the specific documentation needed to support the elimination of endemic rubella virus transmission and consisted of an in-depth analysis of information provided in the annual status update reports and supplementary information from national immunization programs, surveillance networks, and the measles-rubella laboratory networks. The retrospective reviews were shared with the EU-RVC members on an ad hoc basis and provided an opportunity to ask for clarification or additional information before drawing conclusions about a country’s rubella elimination status. Data to complete the rubella retrospective reviews for the last four countries with endemic rubella transmission (Bosnia and Herzegovina, Italy, Poland, and Ukraine) are being collected, analyzed, and formatted for submission to the RVC for their determination.

The findings in this report are subject to at least three limitations. First, sensitivity of integrated measles and rubella surveillance might be lower for rubella than it is for measles because it is a milder illness, resulting in possible detection of fewer cases. Second, direct comparisons between countries might not be valid because of variations in their historic approach to diagnosis, case investigation, and laboratory testing. Finally, the region comprises countries with widely different population sizes and compositions, making regional successes and challenges difficult to measure.

Substantial progress toward rubella elimination has been made in EUR. Verification of elimination is nearly complete, which would make EUR the second WHO region to achieve rubella elimination, the first being the Region of the Americas. Sustaining regional rubella elimination will require maintaining high coverage with RCVs through routine immunization programs at the national and subnational levels, offering supplementary rubella vaccination to susceptible adults, maintaining high-quality laboratory-supported rubella and CRS surveillance for outbreak detection and response, and a fully functioning Regional Verification Commission. Because of the COVID-19 pandemic, additional efforts might be needed to strengthen surveillance systems and fill in the immunity gaps.