Novavax says its Covid-19 vaccine is 89 percent effective, but less so against South African variant

Novavax announced Thursday its Covid-19 vaccine is more than 89 percent effective at protecting against the virus based on preliminary data from a large late-stage trial in the United Kingdom.

But the vaccine was far less effective against a variant of the virus first discovered in South Africa, according to data from a small trial in that country, the company said.