Fauci calls COVID-19 shots' diminished results against the mutated virus 'a wake-up call'

• Johnson & Johnson and Novavax's vaccines have been less effective again a new virus variant.
• "It's really a wake-up call for us," Dr. Anthony Fauci said.
• People should still be vaccinated as quickly as possible, Fauci added.

The US needs to step up efforts to halt the spread of the coronavirus, Dr. Anthony Fauci said Friday, after two vaccines proved to be less effective against a new variant of the virus.

"It's really a wake-up call for us to be nimble and to be able to adjust as this virus will continue for certain to evolve and mutate," said Fauci, who's the director of the National Institute of Allergy and Infectious Diseases.

He spoke on a conference call that the National Institutes of Health held to discuss data on Johnson & Johnson's coronavirus vaccine. J&J said its vaccine was 66% effective at preventing moderate and severe cases of COVID-19 overall, but less effective in South Africa, where a virus variant is spreading. Novavax on Thursday said its coronavirus vaccine was also less effective against that coronavirus variant.

The first US cases of that variant were identified on Thursday.

Fauci said Americans need to be vaccinated as quickly as possible.

"The best way to prevent further evolution of a virus is to prevent it from replicating, and you do that by vaccinating people as quickly as you possibly can," he said during the briefing, which was held with other NIH officials and executives from J&J.

Experts had previously expressed hope that the COVID vaccines currently on the market, as well as those that were in development, would hold strong against variants as long as there were no major changes to the spike protein - a key component of the virus. But the South African variant has alterations to that portion of the virus.

Read more: Moderna is designing a new version of its Covid-19 shot to address a new variant

Even the two vaccines currently on the market in the US, made by Moderna and Pfizer, may be affected by the new variant. Both companies have said that their vaccines should still produce enough protective antibodies to stop the virus, though lab results have shown the protection may be diminished. As a precaution, Moderna and Pfizer are now working on booster shots that could target variants directly.