From the J&J trial results [1]: Vaccine efficacy (VE) against central laboratory-confirmed moderate to severe/critical COVID19 across all geographic areas in

From the J&J trial results [1]: Vaccine efficacy (VE) against central laboratory-confirmed moderate to severe/critical COVID19 across all geographic areas in which the trial was conducted was 66.9% (95% CI 59.0, 73.4) when considering cases occurring at least 14 days after the single-dose vaccination and 66.1% (55.0, 74.8) when considering cases occurring at least 28 days after vaccination. I have seen estimates as low as 40-something % for single doses of the mRNA vaccines, but this may have been an underestimate caused by only considering the first two weeks after inoculation. Given enough time for immunity to fully set in, the real number may be over 90% [2]. HOWEVER, those numbers all refer to symptomatic disease. Prevention of hospitalization and death was 100% in the J&J trial. [1] https://www.fda.gov/media/146217/download https://www.fda.gov/media/146217/download [2] https://www.nejm.org/doi/full/10.1056/NEJMc2036242 https://www.nejm.org/doi/full/10.1056/NEJMc2036242