New coronavirus subvariants escape antibodies from vaccination and prior Omicron infection, studies suggest - CNN

'COVID-19 still has the capacity to mutate further'

In the New England Journal of Medicine paper, among 27 research participants who had been vaccinated and boosted with the Pfizer/BioNTech coronavirus vaccine, the researchers found that two weeks after the booster dose, levels of neutralizing antibodies against Omicron subvariants were much lower than the response against the original coronavirus.

The neutralizing antibody levels were lower by a factor of 6.4 against BA.1; by a factor of 7 against BA.2; by a factor of 14.1 against BA.2.12.1 and by a factor of 21 against BA.4 or BA.5, the researchers described.

Among 27 participants who had previously been infected with the BA.1 or BA.2 subvariants a median of 29 days earlier, the researchers found similar results.

In those with previous infection -- most of whom also had been vaccinated -- the researchers described neutralizing antibody levels that were lower by a factor of 6.4 against BA.1; by a factor of 5.8 against BA.2; by a factor of 9.6 against BA.2.12.1 and by a factor of 18.7 against BA.4 or BA.5.

More research is needed to determine what exactly the neutralizing antibody levels mean for vaccine effectiveness and whether similar findings would emerge among a larger group of participants.

"Our data suggest that COVID-19 still has the capacity to mutate further, resulting in increased transmissibility and increased antibody escape," Barouch wrote in the email.

"We will submit these data to regulators urgently and are preparing to supply our next generation bivalent booster starting in August, ahead of a potential rise in SARS-CoV-2 infections due to Omicron subvariants in the early fall," Bancel said.

The US Food and Drug Administration's Vaccines and Related Biological Products Advisory Committee is meeting next week to discuss the composition of Covid-19 vaccines that could be used as boosters this fall.

The data that Moderna released Wednesday, which has not been published in a peer-reviewed journal, showed that one month after a 50-microgram dose of the mRNA-1273.214 vaccine was administered in people who had been vaccinated and boosted, the vaccine elicited "potent" neutralizing antibody responses against BA.4 and BA.5, boosting levels 5.4-fold in all participants regardless of whether they had a prior Covid-19 infection and by 6.3-fold in the subset of those with no history of prior infection.

These levels of neutralizing antibodies were about 3-fold lower than previously reported neutralizing levels against BA.1, Moderna said.

These findings add to the data that Moderna previously released earlier this month, showing that the 50-microgram dose of the bivalent booster generated a stronger antibody response against Omicron than the original Moderna vaccine.

Moderna's data suggest that "the bivalent booster might confer greater protection against the BA.4 and BA.5 omicron strains than readministering the original vaccine to increase protection across the population.