However, vaccination against Covid-19 is still expected to provide substantial protection against serious disease, and vaccine manufacturers are working on up-to-date vaccines that can elicit a stronger immune response against variants.
“We have seen 3-fold reductions in vaccine and infection-induced neutralizing antibody titers against BA4 and BA5 compared to BA1 and BA2, which are already substantially lower than the original variants of COVID-19,” Dr. Dan Barouch , author of the article. and the director of the Virology and Vaccine Research Center at Beth Israel Deaconess Medical Center in Boston, wrote in an email to CNN.
“Our data suggest that these new subtypes of Omicron are likely to cause increased infections in populations with high levels of immunity to the vaccine, as well as natural immunity BA1 and BA2,” Barouch wrote. “However, it is likely that vaccine immunity will still provide substantial protection against serious diseases with BA4 and BA5.”
Recently, they discovered that BA.4 and BA.5 viruses were more likely to escape antibodies from the blood of fully vaccinated and potentiated adults compared to other subvariants of Omicron, increasing the risk of Covid infection. 19.
BA.4 and BA.5 are the fastest spreading variants reported so far, and are expected to dominate Covid-19 transmission in the United States, the United Kingdom and the rest of Europe in the coming weeks, according to the European Center for Disease Prevention and Control.
“COVID-19 still has the ability to mutate even more”
In the New England Journal of Medicine article, 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, the levels of neutralizing antibodies against Omicron subvariants were far inferior to the response against the original coronavirus.
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 an average of 29 days earlier, the researchers found similar results.
In those with previous infection, most of whom had also 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.
Further research is needed to determine exactly what neutralizing antibody levels mean for vaccine efficacy and whether similar findings would arise among a larger group of participants.
“Our data suggest that COVID-19 still has the ability to mutate even further, leading to increased transmissibility and increased antibody leakage,” Barouch wrote in the email. “As pandemic restrictions lift, it is important that we be vigilant and continue to study new variants and subvariants as they arise.”
As for what all this means in the real world, Dr. Wesley Long, an experimental pathologist at Houston Methodist Hospital, told CNN that people should be aware that they could get sick again, even if they have had Covid. -19 before.
“I think I’m a little worried that people who have had it recently may have a false sense of security with BA.4 and BA.5 on the rise, because we’ve seen some cases of reinfection and I’ve seen some. with people who had a BA.2 variant in recent months, “he said.
Some vaccine manufacturers have been developing variant-specific vaccines to improve antibody responses against worrying coronavirus variants and subvariants.
“Reinfections will be pretty inevitable until we have vaccines or widespread warrants that prevent cases from escalating again. But the good news is that I think we are in a much better place than without the vaccines,” he said. Pavitra Roychoudhury, acting instructor in the Department of Laboratory Medicine and Pathology at the University of Washington, who did not participate in the New England Journal of Medicine.
“There is so much of this virus that it seems inevitable,” he said of Covid-19 infections. “Hopefully the protections we have in place will lead to a mild infection.”
Work is underway to upgrade vaccines against Covid-19
This candidate for a bivalent booster vaccine contains components from both Moderna’s original Covid-19 vaccine and a vaccine aimed at the Omicron variant. The company said it is working to complete regulatory submissions in the coming weeks to request that the composition of its booster vaccine be updated to be mRNA-1273,214.
“Given the continuous evolution of SARS-CoV-2, we are very excited that mRNA-1273,214, our main candidate for the autumn, has shown high neutralizing titles against the subvariants BA.4 and BA.5, which represent an emerging emerging threat to global public health, “Stéphane Bancel, CEO of Moderna, said in a statement on Wednesday. SARS-CoV-2 is the coronavirus that causes Covid-19.
“We will send this data to regulators urgently and prepare to supply our next-generation bivalent booster from August, before a potential increase in SARS-CoV-2 infections due to Omicron subvariants in early autumn, “Bancel said.
Data released by Moderna on Wednesday, which has not been published in a peer-reviewed journal, showed that a month after administering a 50 microgram dose of the mRNA-1273,214 vaccine to people who had been vaccinated and reinforced , the vaccine caused “potent” neutralization of antibody responses against BA.4 and BA.5, increasing levels 5.4-fold in all participants, regardless of whether they had a previous Covid-19 and 6 infection. 3 times in the subset of those with no history of previous infection. Moderna said that these levels of neutralizing antibodies were about 3 times lower than the neutralizing levels previously reported against BA.1.
These findings add to data previously released by Moderna earlier this month, showing that the 50 microgram dose of bivalent booster generated a stronger antibody response against Omicron than Moderna’s original vaccine.
“It has been previously reported that the bivalent vaccine is well tolerated with temporary ‘reactogenic’ effects similar to those following the univalent booster injection, so we can predict that this new mixed vaccine should be well tolerated,” Ward said in part. “As we head into the fall with omicron variants dominating the covid infection landscape, it certainly makes sense to consider using this new bivalent vaccine, if available.”
CNN’s Brenda Goodman contributed to this report.