//Pfizer claims its Covid-19 vaccine is 90 percent effective so far. Here’s what we actually know.

Pfizer claims its Covid-19 vaccine is 90 percent effective so far. Here’s what we actually know.

A worker holds a syringe with Pfizer and BioNTech’s Covid-19 vaccine. The companies announced that their vaccine is more than 90 percent effective in an early analysis. | Dogukan Keskinkilic/Anadolu Agency/Getty Images

The results are promising, but they’re drawn from a very small number of infections.

The American pharmaceutical giant Pfizer and the German biotech firm BioNTech reported on Monday in a press release that their joint Covid-19 vaccine candidate, BNT162b2, is more than 90 percent effective at preventing infection.

That’s great news. It brings the US — and the world — a step closer to another viable Covid-19 vaccine, which we urgently need to help contain and end the pandemic.

“Today is a great day for science and humanity,” said Pfizer CEO Albert Bourla in a statement. “The first set of results from our Phase 3 Covid-19 vaccine trial provides the