Fresh Data Show Effect of South African Virus Variant on Vaccine Efficacy

RIO DE JANEIRO, BRAZIL – Clinical trial data on two COVID-19 vaccines show that a coronavirus variant first identified in South Africa is lessening their ability to protect against the illness, underscoring the need to vaccinate vast numbers of people as quickly as possible, scientists said.

The vaccines from Novavax Inc and Johnson & Johnson were welcomed as important future weapons in curbing deaths and hospitalizations in a pandemic that has infected more than 101 million people and claimed over 2 million lives worldwide.

But they were significantly less effective at preventing COVID-19 in trial participants in South Africa, where the potent new variant is widespread, compared with countries in which this mutation is still rare, according to preliminary data released by the companies.

“Clearly, the mutants have a diminishing effect on the efficacy of the vaccines,” Dr. Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Disease, said in a briefing. “We can see that we are going to be challenged.”

Novavax reported midstage trial results on Thursday that showed its vaccine was 50% effective overall at preventing COVID-19 among people in South Africa.

That compared with late-stage results from the United Kingdom, in which the vaccine was up to 89.3% effective at preventing COVID-19.