J&J 1-dose shot prevents COVID-19, but less than some others

Johnson & Johnson’s long-awaited vaccine appears to protect against COVID-19 with just one shot – not as strong as some two-shot rivals but still potentially helpful for a world in dire need of more doses.

J&J said Friday that in the U.S. 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 U.S. — 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.

“Gambling on one dose was certainly worthwhile,” Dr. Mathai Mammen, global research chief for J&J’s Janssen Pharmaceutical unit, told The Associated Press.

With vaccinations off to a rocky start globally, experts had been counting on a one-dose vaccine that would stretch scarce supplies and avoid the logistics nightmare of getting people to return for boosters.

But with some other competing vaccines shown to be 95% effective after two doses, at question is whether somewhat less protection is an acceptable tradeoff to get more shots in arms quickly.

The company said within a week, it will file an application for emergency use in the U.S., and then abroad. It expects to supply 100 million doses to the U.S. by June, and expects to have some ready to ship as soon as authorities give the green light.

These are preliminary findings from a study of 44,000 volunteers that isn’t completed yet. Researchers tracked illnesses starting 28 days after vaccination – about the time when, if participants were getting a two-dose variety instead, they would have needed another shot.

After day 28, no one who got...