The recently reported dip in the vaccine’s effectiveness in Israel was mostly due to infections in people who had been vaccinated in January or February. The country’s health ministry said vaccine effectiveness in preventing both infection and symptomatic disease fell to 64 percent in June.
“The Pfizer vaccine is highly active against the Delta variant,” Pfizer’s chief scientific officer Mikael Dolsten said in an interview. Six months later, he said, “there likely is the risk of reinfection as antibodies, as predicted, wane.”
Pfizer promised to release the full set of Israeli data soon. “It’s a small data set, but I think the trend is accurate: six months out, given that Delta is the most contagious variant we have seen, it can cause infections and mild disease,” Dolsten said. It would be interesting to see what exactly the data showed.