The Washington Post reports:

A trial of an experimental coronavirus vaccine detected the most sobering signal yet that people who have recovered from infections are not completely protected against a variant that originated in South Africa and is spreading rapidly, preliminary data presented this week suggests.

The finding, though far from conclusive, has potential implications for how the pandemic will be brought under control, underscoring the critical role of vaccination, including for people who have already recovered from infections. Reaching herd immunity — the threshold when enough people achieve protection and the virus can’t seed new outbreaks — will depend on a mass vaccination campaign that has been constrained by limited supply.

Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, noted that it appears a vaccine is better than natural infection in protecting people, calling it “a big, strong plug to get vaccinated” and a reality check for people who may have assumed that because they have already been infected, they are immune.

In the placebo group of the trial for Novavax’s vaccine, people with prior coronavirus infections appeared just as likely to get sick as people without them, meaning they weren’t fully protected against the B.1.351 variant that has swiftly become dominant in South Africa. The variant has been detected only a handful of times in the United States, including a case reported Friday in Virginia, which became the third state to identify the presence of the virus variant.

The preliminary finding from the South African vaccine trial, based on a data set with limitations, stirred debate and concern among researchers as results first hinted at in a news release last week were revealed more broadly this week.

“The data really are quite suggestive: The level of immunity that you get from natural infection — either the degree of immunity, the intensity of the immunity or the breadth of immunity — is obviously not enough to protect against infection with the mutant,” Fauci said.

Even if they don’t agree on the scope of the threat, scientists said reinfection with new variants is clearly a risk that needs to be explored more. There is no evidence that second cases are more severe or deadly, and a world in which people may have imperfect protection against new versions of the virus is not necessarily a world in which the pandemic never ends.

“I worry especially that some of these premature sweeping conclusions being made could rob people of hope,” said Angela Rasmussen, a virologist at Georgetown University’s Center for Global Health Science and Security. “I worry the message they may receive is that we’re never going to be rid of this. When in fact that’s not what the data suggests.”

She and others emphasized the apparent lack of severe health repercussions from reinfection — and the lack of evidence that reinfection is common. [Continue reading…]