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Immunization Science

PCV7 Adverse Events

The article

Postlicensure Safety Surveillance for 7-Valent Pneumococcal Conjugate Vaccine. Wise RP, Iskander J, Pratt RD, Campbell S, Ball R, Pless RP, Braun MM. JAMA 2004;292:1702-1710.

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Explanatory note: Streptococcus pneumoniae can cause serious bacterial infections. There are more than 90 types (or serotypes) of S pneumoniae. In February 2000, the FDA licensed a 7-valent conjugate pneumococcal vaccine (PCV7). Vaccine was recommended for routine administration to children younger than 2 years of age. Prior to licensure, almost 19,000 infants and children received PCV7 in clinical trials.

The Vaccine Adverse Event Reporting System (VAERS) is a national system for reporting possible adverse reactions or side effects after administration of any US-licensed vaccine. VAERS is operated by the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) as a passive reporting system. VAERS accepts voluntary reports from health care providers, parents, patients or anyone else. VAERS has proven useful in detecting early warning signals and to generate hypotheses about possible unrecognized adverse events. However, when analyzing data from VAERS, one needs to take into account the system’s limitations.

The question

Were there adverse events reported after vaccination with the 7-valent conjugate pneumococcal vaccine (PCV7) that warrant further investigation?

The study

This study described the 4,154 case reports to the Vaccine Adverse Event Reporting System (VAERS) [link] following administration of PCV7 in the first two years since licensure (2000-2002). Three quarters of the time PCV7 was administered at the same time as another vaccine.

The findings

The most frequently reported symptoms and signs had been identified in clinical trials: fever, injection site reactions, fussiness, rashes, urticaria, and vasodilation (flushing).

The proportion of reports portraying serious events (14.6%) was similar to that for other vaccines (14.3%)—this proportion does not reflect the real occurrence of adverse events but only the occurrence in the group of people that reported PCV7-realted events to VAERS. These serious events included deaths, life-threatening events, hospitalizations, persistent or significant disabilities and other events of medical importance such as seizures, severe allergic reactions, serum sickness and low platelet count.

There were 23 reports of events that occurred after two doses of PCV7 (also often when another vaccine had also been administered) including fever and irritability, respiratory symptoms, prolonged abnormal crying, gastrointestinal disturbance, allergic reactions, seizures, and hair loss.

There were 34 cases of invasive pneumococcal infections reported that could have represented vaccine failure.

The relevance/bottom line

Most reports to VAERS in the first 2 years after licensure of PCV7 described generally minor adverse events. Symptoms experienced by a few children more than once after successive PCV7 doses and reports of rare but serious events warrant continued surveillance.

NNii’s comment

A growing number of studies have shown that the introduction of PCV7 has resulted in reductions of cases of invasive pneumococcal disease. Although VAERS data have great limitations on their interpretation, this study is reassuring about the safety of PCV7 but also has identified the need for further surveillance for possible vaccine-associated adverse events.

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