By Berkeley Lovelace Jr. -
NBC News
Federal health authorities urge all vaccinated adults to receive the booster dose against COVID-19 amid growing alarm over the omicron variant, a coronavirus strain with multiple mutations that has already been detected in several states of USA.
But some experts worry that
existing booster doses could make future vaccines, if needed, less effective.
Mutations in the variant suggest that it may be able to bypass some of the immunity provided by vaccination or natural infection.
A nurse fills a syringe for patients receiving their COVID-19 booster vaccine from Pfizer-BioNTech in Southfield, Michigan.EMILY ELCONIN / REUTERS
While federal authorities and drug manufacturers await laboratory results to learn the degree of threat that omicron poses to vaccines, for now, existing boosters are the best defense against the new strain and the highly contagious delta variant, according to Dr. Anthony Fauci, chief medical adviser to the White House, epidemiologists and immunologists.
But what is the best strategy for reinforcements in the future?
And if reinforcements are needed for years, as Pfizer CEO Albert Bourla has suggested, will they need to be changed?
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Studies show that an additional dose of current COVID-19 vaccines
"increases levels of neutralizing antibodies against all variants,
" Fauci said at the White House coronavirus response team briefing.
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"There are many reasons to believe that if you get vaccinated and given the booster, you will have at least some degree of cross-protection, most likely against severe disease and even the omicron variant," he added.
This week, Israel's Health Minister, where the third booster dose of Pfizer's vaccine began in the summer, said a fourth dose might be necessary if cases continue to rise.
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Pfizer-BioNTech, Moderna and Johnson & Johnson are working on specific vaccines against the new variant in case laboratory tests show a significant decrease in protection against severe disease,
although it could be months before they are ready for distribution. .
Still, there is a debate among some health experts about whether it is appropriate to use existing vaccines as a booster against new emerging strains, as these were created to combat the original form of the virus identified in late 2019.
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"The point is, if you keep vaccinating and boosting with a strain, which is basically to create an immune response against the ancestral strain, will that limit your ability to create an immune response against a virus, which is very different from the initial one?" said Dr. Paul Offit, a vaccine expert at Children's Hospital of Philadelphia.
Offit describes a phenomenon that immunologists call 'antigenic original sin', in which the body's immune system relies on the memory of its first encounter with a virus, sometimes leading to a weaker immune response when it is subsequently encountered. come across another version of the virus.
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Vaccines can also trigger this phenomenon, said Offit, also a member of the Food and Drug Administration's (FDA) advisory committee on vaccines.
One example is that of the human papillomavirus (HPV), following the release of an updated vaccine that targeted nine strains of the virus instead of just four in the initial injection, he said.
“If you were vaccinated against HPV 4 and then against HPV 9, knowing that the four strains of HPV 4 were also in HPV 9, you had a very good immune response against all four strains, but you did not have such a good immune response against the other five ”, he assured.
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In theory this could also apply to COVID-19, according to Offit.
He added that some experts have argued to wait for a booster until a variant-specific option is available.
it may be best for those who are not at high risk for serious illness.
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He, along with Philip Krause and Marion Gruber, two former FDA officials, wrote an opinion piece published Monday in The Washington Post in which they assured that
booster vaccines should be restricted to people at high risk of suffering from it. a serious illness
, such as the elderly and those who live or work in high-risk environments, such as healthcare workers.
They stated that the original two doses of mRNA vaccines continue to work for most healthy adults.
Michael Osterholm, an epidemiologist and former COVID-19 adviser to President Joe Biden, contested that the third or second dose of mRNA from J&J should be considered part of the primary series of the original vaccine and that people should receive such a booster. As soon as possible.
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A booster dose "can really compensate for the immune evasion that we've seen with this particular variant," Osterholm told MSNBC's Hallie Jackson on Friday.
Ali Ellebedy, an associate professor of pathology and immunology at Washington University School of Medicine in St. Louis, noted that, also in the case of the flu,
having too many antibodies against older strains can interfere with vaccines against other variants of
the virus.
the flu
.
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However, he assured that he rejects the idea that this could happen in the case of COVID-19, at least at this time.
The world's population has not accumulated enough background antibodies against SARS-CoV-2 "to block any further boosts, as happens with the flu in some people," he said.
He also noted that flu vaccines are "low-immunogenic vaccines," which have nothing to do with mRNA vaccines.
Ellen Foxman, an immunologist at Yale University, added that even if the booster with the parent vaccine made future vaccines less effective, it is not "wise" to wait for a variant-specific vaccine to get a booster.
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The bottom line, he said, is that there is a potentially deadly virus that continues to spread across the country and that current vaccines have been shown to protect against it.
Will the current vaccine be as good as it was against the original virus?
"It may or may not, but it will probably provide at least some protection against it," he said.
"If we knew that we need an updated reinforcement and we knew that it was going to come out next week, maybe we would have to wait," he said.
"But the truth is that this coronavirus is around now and it is mostly the delta variant."
Waiting for a specific reinforcement for omicron is a very high risk strategy "
Dr Pete Hotez vaccine researcher
Dr Peter Hotez agreed, adding that the 30- to 40-fold increase in virus-related antibodies generated by booster vaccines may be sufficient against the new strain.
"Whatever happens, you can't wait for the booster shot because delta is still the dominant variant and it will be, I think, for the foreseeable future," said Hotez, co-director of the Texas Children's Hospital Vaccine Development Center. and dean of the National School of Tropical Medicine at
Baylor College
in Houston.
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He added that a specific vaccine for the variant may not be necessary and that there is a possibility that the omicron-specific boosters being developed by drug manufacturers may not work.
Nurse Katherine Pachota, right, prepares to vaccinate veteran Rigoberto Montesinos, 82, during a press conference in February 2021 at the Bay of Pigs Library and Museum in Miami's Little Havana neighborhood. Wilfredo Lee / AP
"Success is not guaranteed," Hotez said.
"Waiting for an omicron-specific booster is a very high-risk strategy."
John Moore, professor of microbiology and immunology at
Weill Cornell Medical College
, said there are still some unknowns about the uses of vaccines, so the "best booster strategy" will emerge over time.
“Everyone wants instant answers, but the most important thing is to get the correct answers.
That takes time, ”he said.