Both vaccines were highly effective in preventing infection in January, before the introduction of Delta — hovering at around 90 percent — by July the effectiveness of both shots had dropped. Moderna was down to 76 percent, Pfizer was down to 42%. The study was conducted among over 50,000 patients.
In Florida, which is currently experiencing its largest COVID-19 surge to date, the risk of infection in July after full vaccination with Moderna shot was about 60% lower than after full vaccination with Pfizer