Sunday, February 3, 2013

Gathering Data on Vaccinations

The Vaccine Safety Datalink (VSD) a collaborative effort between CDC’s Immunization Safety Office and nine Managed Care Organizations (MCOs) are monitoring immunization safety gaps in scientific knowledge related to rare and serious events following immunization.

The VSD includes a large linked database with immunization histories on more than 9 million people available from administrative data sources at each MCO. Each participating site gathers data on the vaccine type, date of the vaccination, and data on concurrent vaccinations, plus medical outcomes in terms of outpatient visits, inpatient visits, and urgent care visits, along with birth and census data.

In addition, the VSD team launched an active surveillance system called “Rapid Cycle Analysis” (RCA). The system updates data every week from studies done on vaccines before they are licensed, early adverse events reports, and addresses concerns published in scientific articles. The VSD Project team uses RCA to monitor newly licensed vaccines and new vaccine recommendations. 

CDC developed their “Vaccine Adverse Event Reporting System” (VAERS), a national passive reporting system that accepts reports from the public on adverse events associated with vaccines licensed in the U.S. The data is used to monitor increases in adverse events, identifies potential patient risk factors for particular types of adverse events, identifies vaccine lots, and assesses the safety of newly licensed vaccines. 

Healthcare providers when vaccinating children follow a schedule prepared by the U.S Advisory Committee on Immunization Practices. The current recommended childhood immunization schedule is timed to protect children from 14 pathogens by inoculating them at the time in their lives when they are most vulnerable to disease.

HHS is involved in vaccination issues since the agency studies parents concerns related to the potential side effects from vaccines and scheduling concerns. HHS asked the Institute of Medicine (IOM) to identify research approaches, methodologies, and study designs to address questions about the safety of the current childhood immunization schedule.

The IOM Committee has produced the report, “The Childhood Immunization Schedule and Safety: Stakeholder Concerns, Scientific Evidence, and Future”. The report makes the point that the VSD tracks people from only eight states and tracks a smaller percentage of low-income and minority people than is in the U.S. population as a whole.

The report also said that newer data collection and surveillance systems offer great potential to monitor rare adverse events that may be associated with the childhood immunization schedule. For example, the FDA Sentinel Initiative to monitor the safety of approved drugs and other medical products will complement existing passive vaccine surveillance systems, the report says.

Also, FDA’s new Post –License Rapid Immunization Safety Monitoring Program is amassing a large amount of health data and offering the potential to analyze vaccine exposures and adverse events with a greater degree of statistical power.

Although randomized controlled trials are the gold standard for clinical research, such a trial cannot be safely and efficiently performed to compare health outcomes among vaccinated and unvaccinated or differently immunized children, the committee concluded.

For a pre-publication of the IOM report, go to More information is available at or call (202) 334-3313 or 1-800-624-6242.