Accessing and Using Data from the Vaccine Safety Datalink (VSD)

Public use datasets

Public use datasets from two VSD studies are available upon request:

• "Prenatal and Infant Exposure to Thimerosal from Vaccines and Immunoglobins and Risk of Autism"
• "Infant and Environmental Exposures to Thimerosal and Neuropsychological Outcomes at Ages 7 to 10 Years"

Outside researchers may learn more about each study through the study documents and reports and through the data files. Researchers can request access to these public use datasets via email request to CDC.

VSD data sharing program

VSD datasets have been helpful in:

• Finding and examining potential vaccine side effects.
• Addressing public concerns about vaccine safety.
• Exploring risk factors associated with vaccine safety.
• Monitoring vaccine safety trends over time.

These datasets give important information that helps researchers:

• Find rare problems.
• Check if safety concerns are valid.
• Guide health policies and recommendations.

CDC's National Center for Health Statistics Research Data Center (NCHS RDC) manages the VSD data sharing program. Accessing VSD data requires a three-step process:

1. Submit study proposal to NCHS RDC.
2. Submit proposal to an Institutional Review Board (IRB) for research determination.
3. Access VSD data at NCHS RDC.

Permitted uses of data

Outside researchers can request access to VSD data to reanalyze study-specific datasets. Datasets do not contain personal health information.

• Outside researchers can request final datasets from published VSD studies from the past 10 years for reanalysis.
• The NCHS RDC will provide the necessary data dictionary for the requested dataset.
• No other raw data or earlier versions of the dataset are available for reanalysis.
• Once outside researchers meet the proposal requirements, they can access a dataset(s) at a secure NCHS RDC.

Submitting a proposal

Required information

1. Project/study title.
2. Name of proposed investigator and collaborators.
   1. Per NCHS RDC rules, a maximum of three people may use a workstation.
3. Name, address, telephone number and email address of point of contact.
4. Summary of proposed study, including:
   1. Background.
   2. Reasons for conducting the study.
   3. Public health benefits.
5. Specific hypothesis of vaccine safety study to be investigated or title of published VSD study to be reanalyzed.
6. Proposed methodology for new vaccine safety study to be investigated, or specific methods used in published study. The NCHS RDC will not accept abstracts of published studies as proposed methodology for new studies or reanalyses. Description of methodology must include the following:
   1. Defined study population of interest (including age of population, study years of interest, and approach used to select study population from VSD data files).
   2. Type of study to be conducted (for example, descriptive study, case-control study, cohort study).
   3. Specific variables to be required, including exposures, outcomes of interest, person-time or enrollment, confounding or control variables, proposed analytic strategies and statistical methods.
   4. Detailed proposed strategies for analysis and statistical methods (to help reviewers plan for disclosure review).
   5. IRB determination statement: “I have received an IRB determination for the proposed research and have attached the IRB-reviewed protocol and approval letter.” This step takes place after CDC initial review of proposal.

Proposal review process

NCHS RDC review

Process and requirements

1. NCHS RDC reviews proposal based on required criteria. Requirements:
   1. Completion of proposal.
   2. Review of the scientific and technical feasibility of the project. Determination is based on if requested data are available (for new vaccine safety studies) or if requested final dataset is available (for reanalysis).
   3. Assessment of availability of resources at the NCHS RDC. If requested data are not available, CDC will notify the outside researcher. The researcher may then resubmit the proposal to use other available data, if desired.
   4. Evaluation of risk of disclosure of restricted information.
2. NCHS RDC notifies researcher(s) whether the proposal meets the evaluation criteria.
   1. If so, researcher can submit proposal to next step (IRB review).
   2. If not, researcher may submit new proposal based on missing/unmet criteria.

IRB review

Process and requirements

1. The outside researcher will be responsible for submitting the proposal to an IRB for approval or determination.
   1. Individual IRB requirements may vary. IRB applications may require more information about the proposed vaccine safety study than the required information for the NCHS RDC proposal.
2. Once outside researcher receives IRB approval or determination, they are to share approval letter and final version of protocol via email to the NCHS RDC.
   1. Review of a proposal submitted by an outside researcher by CDC does not imply that CDC approves or endorses the proposed research.
   2. Approval does not allow the outside researcher to gather more data within the participating health plans' member medical records or elsewhere.

Approved proposals: data preparation and sharing process

1. Each researcher included in proposal submits a signed copy of the NCHS RDC Agreement Regarding Conditions of Access to Confidential Data and the NCHS RDC Researcher Affidavit of Confidentiality.
2. NCHS RDC creates or formats the approved dataset(s) for approved proposal.
   1. NCHS RDC will not create nor prepare the dataset(s) until it receives a copy of the final IRB disposition and signed copies of NCHS RDC Conditions of Access and Researcher Affidavits.
3. NCHS RDC arranges researcher(s) data access as described in the general data sharing document. All rules, procedures and fees will apply.

Requirements for researchers publishing research using VSD data

Required disclaimers in manuscripts

• "The research was conducted using data from the Vaccine Safety Datalink Project, through the data sharing program at the Centers for Disease Control and Prevention."
  • Any published material using VSD data must acknowledge CDC as the original data source.
• "The analysis, interpretations, and conclusions reported here are the responsibility of the authors and do not represent the views and opinions of the Centers for Disease Control and Prevention, the Federal Government, or participating Vaccine Safety Datalink health plans."

Required documents when submitting manuscripts to journals

• Submit a copy of the data sharing guidelines.
• Submit a copy of the signed Agreement Regarding Conditions of Access to Confidential Data associated with the proposal.

Resources

Recommended references for VSD researchers

• Baggs J, Gee J, Lewis E, Fowler G, Benson P, Lieu T, Naleway A, Klein NP, Baxter R, Belongia E, Glanz J, Hambidge SJ, Jacobsen SJ, Jackson L, Nordin J, Weintraub E. The Vaccine Safety Datalink: A model for monitoring immunization safety. Pediatrics 127 Suppl 1: S45,S53, 2011.
• Chen RT, DeStefano F, Davis RL, Jackson LA, Thompson RS, Mullooly JP, Black SB, Shinefield HR, Vadheim CM, Ward JI, Marcy SM, Vaccine Safety Datalink Team. The Vaccine Safety Datalink: Immunization research in health maintenance organizations in the USA. Bulletin of the World Health Organization 2000;78:186-194.
• Chen RT, Glasser J, Rhodes P, Davis RL, Barlow WE, Thompson RS, Mullooly JP, Black SB, Shinefield HR, Vadheim CM, Marcy SM, Ward JI, Wise RP, Wassilak SG, Hadler SC. The Vaccine Safety Datalink Project: A new tool for improving vaccine safety monitoring in the United States. Pediatrics 1997;99:765-773.
• DeStefano F. The Vaccine Safety Datalink project. Pharmacoepidemiol Drug Saf 10: 403,6, 2001.