Experts studying the effectiveness of the Pfizer/BioNTech vaccine against the coronavirus have concluded that the risk of contracting the virus increases over time after receiving the second dose of the vaccine. The British news agency PA Media reported that the team, which published the study in the British Medical Journal, stated that the findings support the need for booster doses to prevent individuals from contracting the virus as immunity wanes.
A team from the Leumit Health Services Institute in Israel found a gradual increase in the risk of COVID-19 infection after 90 days of receiving the second dose of the Pfizer vaccine. It is noted that Israel was one of the first countries to conduct an extensive vaccination campaign against COVID-19 in December 2020, but it is currently facing a rise in cases and is examining the decline in immunity against the virus.
The experts examined the electronic medical records of 80,057 adults (with an average age of 44) who underwent PCR testing from May to September of the previous year, at least three weeks after receiving the second dose of the vaccine. The examination showed no evidence of previous COVID-19 infections in any of the samples. Among the group tested, 7,973 individuals (9.6%) were found to be infected with COVID-19.
The results were then matched with individuals of the same age and ethnicity who tested negative for the virus in the same week. The study concluded that the rate of positive results increases over time after receiving the second dose of the vaccine.
