Johnson & Johnson’s COVID-19 vaccine appears to protect against the novel coronavirus with just one shot. While it is not as effective as other two-shot rivals, it is still potentially helpful for a world in dire need of more vaccine doses.
J&J on January 29 said that in the US and seven other countries, the single-shot vaccine was 66% effective overall at preventing moderate to severe illness, and much more protective (85%) against the most serious symptoms.
There was some geographic variation. The vaccine worked better in the US — 72% effective against moderate to severe COVID-19 – compared to 57% in South Africa, where it was up against an easier-to-spread mutated virus.