The protection of Pfizer / BioNTech COVID-19 against severe cases remains stable after six months. new information published by the companies. But its ability to protect people from developing the symptoms of the disease decreased over time, the analysis showed.
The information may add to the debate about whether people need vaccines at any time that Biden’s administration, Centers for Disease Control and Prevention, and other experts have been discussing in recent months. The issue became more compelling as COVID-19 cases in the United States began to rise with the spread of the Delta variant.
Overall, the vaccine was 91% effective against symptomatic COVID-19 over six months. It was the most protective stretch that started seven days after the second dose and ran for two months: in that window, it was 96 percent effective. Its efficacy then decreased by about 6 percent every other month to 90 percent between two and four months after vaccination and to about 84 percent between four and six months after vaccination.
There was no corresponding reduction in efficacy against serious cases of COVID-19 – defined in cases where the blood oxygen level falls below 93 percent and the heart and breathing heart rate are elevated. The effectiveness of the vaccine against these serious cases remained high at 97 percent after a full six-month period when people received their shots.
The data was pre-published by Pfizer and has not been verified by external researchers. It was released on the day of the company’s earnings call, where it was also published internal information indicating that a third dose of the vaccine may increase antibody levels against the Delta variant of the virus.
The results came from a study launched last summer to test the safety and effectiveness of the vaccine. the first set of observations the results of that study were used by the Food and Drug Administration to approve the shot. The companies continued to follow over 42,000 participants in the study to check vaccine performance over time.
The analysis also did not identify any new safety concerns in people who had been vaccinated for six months. The company will monitor participants for two years after receiving the vaccines.