With new data, Pfizer and BioNTech say that the protection their SARS-CoV-2 vaccine provides against infection declines over time, though it still offers protection against serious disease, the New York Times reports. It adds that Pfizer is using the findings to bolster its case for a vaccine booster dose.
In a preprint posted to MedRxiv, the companies report that the efficacy of their vaccine in preventing COVID-19 was 91 percent over six months. But they found that that efficacy decreased over time by an average of 6 percent every two months, or to about 84 percent after four to six months. Efficacy in preventing severe disease, though, remained high, around 97 percent.
The Wall Street Journal notes that this data pre-dates the rise of the Delta variant in the US. Data from health officials in Israel have also suggested a decline in efficacy of the vaccine against the Delta variant.
Pfizer and BioNTech announced earlier this month that they were studying a booster dose of the vaccine, saying that it could increase neutralization titers. But US health officials pushed back against the idea of a booster shot. In a joint statement, Centers for Disease Control and Prevention and the Food and Drug Administration said there is no need yet for a booster. After meeting with Pfizer, FDA reiterated that more data was needed to determine whether a booster is needed.
According to the Journal, Pfizer plans to seek regulatory authorization in the US for a booster next month.