Federal health officials are Calling on all vaccinated adults to get a booster shot of Covid amid growing alarm about the omicron variant, a heavily mutated coronavirus strain has been discovered in several states across the US But some vaccine experts worry that many booster doses of existing vaccines could make future vaccines, if needed, less effective.
NS mutations of the variant suggests that it may evade some of the immunity provided by vaccination or natural infection. While federal health officials and drug manufacturers await the highly anticipated lab results to see What is the threat omicrons pose to vaccines?“For now, existing boosters are the best defense against the new strain of bacteria and the best defense against them,” said Dr. Anthony Fauci, chief medical adviser to the White House, epidemiologists and immunologists. delta variant is highly transmissible.
But what is the best strategy for future boosters? And if boosters are needed for years to come, as Pfizer CEO Albert Bourla has suggested, do they need to be modified?
Studies show that additional doses of the current Covid vaccine “increase levels of neutralizing antibodies against all variants,” said Fauci, director of the National Institute of Allergy and Infectious Diseases. learned Friday at the White House Covid-19 Response Team press conference. “There’s every reason to believe that if you get vaccinated and boosted you’ll at least have some degree of cross-protection, most likely against severe disease, even against the omicron variant.”
This week, Israel’s health minister, start giving the third dose Pfizer enhanced shot in summer, said that a fourth booster dose may be needed if the country’s Covid cases continue to rise.
Pfizer-BioNTech, Moderna and Johnson & Johnson are working on a specific vaccine omicron for use against the new variant if laboratory tests show significant reduction in protection against severe disease, although it may take several months before they are ready to be distributed.
However, there is still discussion among some health professionals about whether it is appropriate to use existing vaccines as boosters against emerging new strains of the virus, as the injections are still formulated to target the original form of the virus identified in late 2019.
“The question is, if you continue to prime and boost with a strain, essentially to induce an immune response against the ancestral strain, will that limit your ability to generate an immune response? for viruses, is this very different from ancestors?” said Dr. Paul Offit, a vaccine specialist at Children’s Hospital of Philadelphia.
Offit is describing a phenomenon that immunologists call “primary antigenic sin,” in which the body’s immune system relies on memories of its first encounter with the virus, sometimes leading to a response. weakened immunity when subsequently encountering another version of the virus.
Offit, who is also a member of the Food and Drug Administration’s vaccine advisory committee, says vaccines can also trigger the phenomenon. One example, he said, is with the human papillomavirus, or HPV, after the release of an updated vaccine that targets nine strains of the virus instead of just four in the original shot.
“If you get HPV4 and then get HPV9, know that the four strains in [HPV]4 people are also in [HPV]9, you had a very good immune response to four strains, but you didn’t have a good immune response to the other five strains,” he said.
Theoretically, it could also apply to Covid, Offit said.
He says some experts have argued that it may be better for people who are not at high risk of serious illness to wait for booster injections until a specific option for each variant is available.
He, along with Philip Krause and Marion Gruber, two former FDA officials, wrote an op-ed published Monday in The Washington Post argues that booster shots should be limited to those at high risk of severe illness, such as the elderly, and those who live or work in high-risk settings, such as healthcare workers. They say the initial two doses of the mRNA vaccine are still working for most healthy adults.
Michael Osterholm, an epidemiologist and former Covid adviser to President Joe Biden, countered that the third dose of J&J mRNA or the second dose should be considered part of the initial vaccine series and that people should booster injection as soon as possible. Osterholm told MSNBC’s Hallie Jackson on Friday.
Ali Ellebedy, associate professor of pathology and immunology at Washington University School of Medicine in St. Louis, points out that for influenza, having too many antibodies against previous strains can interfere with vaccination against other flu variants.
However, he said he rejected the idea that this could happen with Covid, at least for now.
The global population has not accumulated enough baseline antibodies against SARS-CoV-2 “to prevent any further increase, which is the case with influenza for some,” he said. He also notes that the flu vaccine is a “poor immunogenic vaccine,” unlike the mRNA vaccine.
Even if the initial booster vaccine makes future vaccines less effective, waiting for a shot, says Ellen Foxman, an immunologist at Yale University. injecting specific variation to increase efficiency is not “wise”. The bottom line, she said, is that there is a life-threatening virus that is still spreading across the country and current vaccines have been shown to provide protection against it.
Will the existing shot be as good as it was against the original virus? “It may or may not, but it will likely provide at least some protection against it,” she said.
“If we know we need an updated booster and we know it’s coming out next week, maybe you should wait,” she said. “But the truth is, this coronavirus is popping up all over the place and it’s mostly plain variant.”
Dr. Peter Hotez agrees, adding that a 30 to 40-fold increase in virus-associated antibodies produced by booster shots may be enough to fight the new strain of virus.
“No matter what, you can’t wait for your boost because delta is still the dominant variant and will be,” said Hotez, co-director of the Vaccine Development Center at Texas Children’s Hospital. I think in the near future”. and chair of the National Department of Tropical Medicine at Baylor College of Medicine in Houston.
There may not be a need for a variant-specific vaccine, he added, and it is likely that the omicron-specific boosters that drugmakers are developing won’t work.
“A downhill sled is not guaranteed,” says Hotez. “Waiting for a specific omicron-enhancing drug is a very high-risk strategy.”
John Moore, a professor of microbiology and immunology at Weill Cornell Medical College, said there are still some unknowns about the use of vaccines and therefore the “best promotion strategy” will emerge. appear over time.
“Everybody wants an answer right away, but it’s more important to get the right answer. That takes time,” he said.
