One is the J&J vaccine was tested later into the pandemic, when there was more circulating virus and after variants that are more easily transmissible were discovered. It's unknown whether the Pfizer or Moderna vaccines would have fared any better under the same circumstances. Perhaps most important of all, the J&J vaccine was 85% effective overall at doing what we care about most: preventing hospitalizations and deaths. Another big area of speculation is whether any of the vaccines work well against the variants that are emerging around the globe. And starting next week, vaccines will also be sent nationwide to 250 community health centers, which serve vulnerable populations.

Source: The Nation February 12, 2021 12:00 UTC