Large study shows high protection of 3 vs 2 Pfizer COVID vaccine dosesA third Pfizer COVID-19 vaccine dose is 92% more effective in reducing severe COVID-related outcomes than two doses of the same vaccine received at least 5 months previously, according to a large real-world study late last week in The Lancet.The study, conducted by researchers with the Clalit Research Institute in Israel and Harvard University, took place from Jul 30 through Sep 23, during Israel's fourth COVID-19 wave, when the Delta (B1617.2) variant was overwhelmingly predominant.The scientists reviewed data from 728,321 Israelis aged 12 or above who had received the third Pfizer dose and matched them with the same number of people who had received the two-dose series