Rapid Cycle Analysis (RCA)

Recent events in the United States highlight the importance of setting up computerized reporting systems to detect adverse events as they happen. In 2005, the Vaccine Safety Datalink (VSD) Project team launched an active surveillance system called Rapid Cycle Analysis (RCA). Its goal is to monitor adverse events following vaccination (possible side effects) in near real time, so the public can be informed quickly of possible risks. The VSD Project team uses RCA to monitor newly licensed vaccines and new vaccine recommendations.

RCA data come from participating managed care organizations that include more than 8.8 million people annually, representing nearly 3% of the United States population. The RCA data contain no personal identifiers.

How RCA Works

RCA uses data that are updated every week. Potential adverse events that are monitored for each RCA project are based on—

• data from studies done on vaccines before they are licensed for general use
• early analyses from the Vaccine Adverse Event Reporting System (VAERS)
• concerns found in published scientific articles

Each week, the rate of adverse events that occurs in people who have received a particular vaccine are compared to the rate of adverse events that occurs in a similar group of people who have not received that vaccine. If the rate of adverse events among vaccinated people is significantly higher than among the comparison group, the vaccine may be associated with an adverse event. To find out if a vaccine truly increases the risk of a particular adverse event, VSD Project scientists conduct a formal epidemiologic study.

The VSD Project team is using RCA to monitor the safety of all newly licensed vaccines, including conjugated meningococcal vaccine, rotavirus vaccine, MMRV vaccine, Tdap vaccine, and HPV vaccine. In addition, plans are underway to use RCA to monitor the safety of seasonal influenza (flu) vaccinations.