Biz Health 18 Jan 2021
"All three COVID-19 vaccines had durable effectiveness in reducing the risks of hospitalisation and death, found a US analysis of 10.6m people.
The study found that effectiveness of the Pfizer and Moderna mRNA vaccines in reducing the risk of COVID-19 reached a peak of about 95% at two months after the first dose and then gradually declined. At seven months, the Pfizer vaccine dropped to 67% effectiveness, compared with the Moderna vaccine, which maintained 80% effectiveness. Among early recipients of the two mRNA vaccines, effectiveness dropped dramatically from mid-June to mid-July, when the Delta variant was surging.
Effectiveness for the Johnson & Johnson adenovirus vaccine was 75% at one month after injection and fell to 60% after five months.
All three vaccines were effective at keeping people out of the hospital with severe COVID-19. Effectiveness of the Pfizer vaccine reached a peak of 96% at two months and remained around 90% at seven months; effectiveness of the Moderna vaccine reached a peak of 97% at two months and remained at 94% at seven months.
Effectiveness of the Johnson & Johnson vaccine reached a peak of 86% at two months and was higher than 80% through six months.
For all three vaccines, effectiveness against death was higher than that of hospitalisation.
Results of the study, University of North Carolina at Chapel Hill, published in the New England Journal of Medicine, suggest that declining immunity is responsible for breakthrough infections, but vaccines maintained protection from hospitalisation and severe disease nine months after getting the first shot.
“The primary takeaway message from our study is that unvaccinated people should get vaccinated right away,” said lead study author Danyu Lin, PhD, Dennis Gillings Distinguished Professor of Biostatistics at the UNC Gillings School of Global Public Health. “The results also underscore the importance of booster shots, especially for older adults.”"
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