US and Europe prepare to approve Omicron vaccine: Here’s what you need to know

Two and a half years after its appearance Corona virus And one and a half from the beginning of the use of vaccines against The world is preparing to receive the first reprogrammed reinforcements to protect against Omicron, the disease it causes, Covid-19. The current variant of the pathogen in circulation.

The downside is that the new injection will block against variation The Ómicron or BA.1 is no longer in circulation as sub-variants BA.4 and BA.5 have eclipsed it in the past three months. Last June, the US Food and Drug Administration (FDA) asked manufacturers to develop a booster specifically targeting those two subtypes, and last week, Both Moderna and the Pfizer-BioNTech collaboration said they submitted data on their BA.4/BA.5 vaccine to the FDA. President Joe Biden’s administration has already ordered 170 million doses of the vaccine.

The United Kingdom has already authorized an injection made by vaccine manufacturer Moderna against Ómicron’s BA.1 subtype. You can start using it soon. This week, after encouraging data was published in the journal Science, the European Medicines Agency (EMA) began reviewing applications for Moderna and Pfizer-BioNTech’s BA.1 vaccine. a) Yes, The EU may first approve a BA.1-based booster and then switch to BA.4/BA.5 vaccines. However, data on renewed reinforcements are limited and the impact they would have if given the green light is unclear.

What’s in the new boosters?

They have some old and some new. Both the Pfizer-BioNTech and Moderna collaborations produce their vaccines from the messenger RNA (mRNA) that encodes the spike protein of SARS-CoV-2. The new vaccines are twofold. Half of the mRNA codes for the spike protein of the ancestral strain of the virus that emerged in Wuhan, China in late 2019, which is also seen in the original footage. The other half encodes the spike protein BA.1 or BA.4 and BA.5, which have identical spikes.. Because they contain low levels of mRNA, the shots are designed to be used only as boosters, not for unvaccinated individuals.

Human data is only available for corporate boosters targeting BA.1. At a June meeting of the FDA’s Vaccine Advisory Committee, both Pfizer-BioEnTech Collaboration as Modern The data showed that the injections had similar side effects to the original vaccines, including pain and fatigue at the injection site, and induced strong antibody responses to both the original strain and Omicron BA.1. The companies showed that BA.1 vaccines elicited significant antibody responses to BA.4 and BA.5, although less so than BA.1.

Animal testing only

Central health officials expect The new vaccines provide stronger protection against existing booster shots, It still attacks the original strain of the coronavirus. But due to a lack of human data, officials won’t know how effective the new injections are until a booster campaign begins next month.

For BA.4/BA.5 boosters, companies submitted animal data only. Although Pfizer presented preliminary findings in eight mice that received a third dose of the BA.4/BA.5 vaccines at an FDA meeting in June, they have not released that data publicly. Compared to mice that received the original vaccine as a booster, the animals showed a greater response to all omicron types tested: BA.1, BA.2, BA.2.12.1, BA.4 and BA.5.

That’s what companies say Clinical trials for BA.4/BA.5 vaccines begin next month; They need clinical data to allow full vaccination (their recent submissions are for emergency use authorization only) and to help develop future updates. Presumably, they measure recipient antibody levels, but not the effectiveness of the vaccine against serious infection or disease. These tests are very expensive and not even carried out for the BA.1 shot.

When the FDA licensed the first versions of Pfizer and Moderna’s Covid vaccines in late December 2020, it made decisions based on safety and efficacy data from tens of thousands of trial volunteers. The new injections from Pfizer and Moderna are called bivalent vaccines, designed to attack the Omicron BA.4 and BA.5 subtypes., as well as the original strain of the coronavirus, in a single dose. Because of the high levels of immunity from previous vaccines and infections, it’s not possible for companies to test the new boosters in the same way as the original shots.

How can authorities consider approval of vaccines without data from human trials?

Influenza vaccines are updated each spring to try to match the strain circulating in the fall and winter.. Reconstituted vaccines do not have to undergo new clinical trials unless manufacturers significantly change the way they make the vaccine. A similar approach to new COVID-19 strains makes sense, said Leif Eric Sander, an infectious disease specialist at Berlin’s Charité University Hospital. “It’s an ethical question” that the changes in mRNA are small and giving updated vaccines as quickly as possible.Xander pointed out. “We need to allow people to protect themselves from a virus that we cannot fully control,” he added.

But there is a potential drawback: Approving updated vaccines without clinical data can reduce public acceptance. “If a booster variant is going to reduce overall acceptance, that’s a potential problem,” said Deborah Cromer, a mathematical modeler at the Kirby Institute at the University of New South Wales, which could offset gains in protection from the new vaccine.

Why do new vaccines still contain mRNA targeting a long-lost ancestral strain?

This is not entirely clear. Hana El Sahli, a vaccine development expert at Baylor College of Medicine, says she can’t see a biological reason to include both versions of the spike. In Pfizer’s mouse experiments, the Omicron-only vaccine elicited slightly higher antibody responses against Omicron viruses than the bivalent vaccine.

But the limited human data available show no significant difference between the two formulations.. However, Rochester Medical Center’s Angela Branch, who is leading a study comparing multiple strain-specific vaccines, notes that the next variant may be more closely related to the ancestral strain than Omicron.

The FDA’s decision to consider Covid boosters without human data is consistent with how it evaluates flu vaccines, which is modified each year.. Approval of seasonal flu vaccines does not require human clinical studies, even if they are reformulated for strain changes, said Dr. Jesse Goodman, former head of FDA vaccines at Georgetown University.

However, the flu shot is not a fair comparison, said Dr. Paul Offitt, a vaccine specialist at the Children’s Hospital of Philadelphia. The FDA’s policy on influenza vaccines is based on decades of experience with strains of influenza vaccines that generally work the same way.. The United States is still in its first iteration of Covid vaccines, and mRNA technology has only been widely used since the late 2020s.

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