The FDA's effectiveness data includes an analysis of 39,321 participants, also mostly from South Africa, South America, Mexico and the US. They did not have evidence of a COVID-19 infection before receiving the vaccine.
• 19,630 participants received the vaccine
• And 19,691 received a placebo.
The FDA found the vaccine to be 67% effective in preventing moderate to severe COVID-19 occurring the first two weeks after vaccination and 66% effective in preventing moderate to severe/critical COVID-19 at least 28 days after vaccination.
Between the effectiveness of a single dose and months-long stability in a simple medical refrigerator, the J&J vaccine truly is a game-changer. We all look forward to a time when Coronavirus vaccines are "one and done" and available in the most remote corners of the world. The fight against COVID-19 happening on a global battleground, not only a domestic one.