Vaccines against COVID: our current vaccinations could be updated soon to target new variants, says an immunology expert

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More than two years after the pandemic, SARS-CoV-2, the virus that causes COVID-19, continues to challenge us. Their ability to mutate rapidly has seen the evolution of increasingly infectious variants that are improving to hide from our immune response.

Vaccines are a great achievement of modern science and have played a crucial role in reducing the worst impacts of VOCID. But are the vaccines we currently have able to cope with the newer variants of COVID?

Current COVID vaccines are all based on the genetic blocks, or DNA sequence, of the original ancestral strain of SARS-CoV-2. Most of these vaccines target the tip protein, the part of the virus that binds to our cells to enter.

Vaccines work by allowing our immune cells to mount a targeted response to the ear protein, including the generation of antibodies known as neutralizing antibodies. This prevents viruses from entering our cells and helps other immune cells find and destroy any viral intruder.

But SARS-CoV-2 is a slippery client and has been mutating with notable changes in ear protein. This means that vaccine-induced neutralizing antibodies are less effective than before.

Is it time for a new generation of vaccines against COVID?

The idea of ​​vaccinating against variants instead of the ancestral strain is gaining strength. This is not a new concept in vaccine development. Our annual flu vaccinations, for example, target circulating variants.

One approach is to create what is called a “bivalent” vaccine that targets the omicron ear protein (BA.1) as well as the ancestral strain. Moderna is currently testing this option in combined phase 2 and 3 human assays. Data that have not yet been reviewed in pairs suggest that this translates into a doubling of the neutralizing antibodies against BA.1, compared to the original vaccines against COVID.

Other trials of Moderna are analyzing different bivalent combinations, including vaccines targeting ancestral and beta strains, that look promising.

Pfizer has also published test data on its reinforcement candidate specifically tailored to BA.1. The company says this reformulation induced a higher immune response to BA.1 than that produced by its original COVID vaccine.

So should we invest in these new vaccine candidates? The U.S. Food and Drug Administration seems to think so, having recently approved the use of these specific omicron injections later this year.

However, investing in and deploying new vaccines is not cheap, and there are important questions we need to address. As we know, SARS-CoV-2 is constantly mutating and changing. Less than a year ago the delta strain dominated the whole world, and before that we had alpha and beta. So are omicron variants the right ones to target? Will they be dominant in a year? We just don’t know.

Even with omicron strains there is variation. The BA.1 variant to which these new vaccine candidates are directed has recently been overtaken by BA.4 and BA.5. Variants BA.4 and BA.5 are even more resistant to neutralizing antibodies, usually three or four times, than BA.1. So the question is, if omicron permeates, will these omicron BA.1 vaccines work better against BA.4 and BA.5 than the original vaccines? Data yet to be reviewed in pairs suggest that bivalent vaccines may be slightly better than the original vaccines.

However, omicron may be a candidate for a poor vaccine, as recent data show that omicron infection does not produce robust immunity and is characterized by low levels of neutralizing antibodies, which must be higher and more persistent. to prevent rapid reinfection. This could help a lot in explaining why so many of us are taking COVID multiple times. If we look at the same with our vaccine-induced omicron immunity, omicron-specific vaccines may not be a worthwhile investment.

Other strategies

None of this means we should stop looking for long-term protective vaccines. But perhaps there is room to focus on different strategies. Two interesting avenues are emerging.

The first are vaccines that target other parts of the viral structure that are more stable, or vaccines that target various parts of the virus. This may not result in a vaccine that can completely prevent infection, but it may be more durable than current vaccines.

Another route is to take advantage of the ability to neutralize antibodies in the nose and throat to target SARS-CoV-2 at its point of entry. These antibodies create a barrier that prevents the virus from entering the body, so a vaccine that generates neutralizing antibodies in the nose and throat could stop the virus in its path. Studies that are testing nasal vaccines look promising, although they are still in their early stages.

Where does this leave us now? An ideal candidate for the vaccine would get long-lived neutralizing antibodies and give us lifelong immunity. Instead, we have learned that for COVID, our immune system needs reinforcements to complete the neutralizing antibodies and strengthen the number of memory cells that support immunity.

The last booster campaign across the UK was in December 2021. Studies had shown that vaccination against COVID followed by an infection led to months of immunity, but that was before omicron, which we now know does not produce robust immunity. Against omicrons, many of us will be left with minimal neutralizing antibodies.

With the high probability of another variant in the fall, along with fears of a bad flu season, it would seem prudent to embark on an autumn reinforcement campaign with much broader coverage than the spring campaign. This means not only targeting those over 65 and others at higher risk, as currently planned, but expanding eligibility to younger age groups.

Crucially, we need to reach out to those who are not fully vaccinated, so any campaign should include targeted community education. This should also happen along with other mitigation strategies such as the use of masks to keep us safe and allow us to live with COVID.

Should you receive a COVID-19 booster vaccine now or wait until the fall? Two immunologists help weigh the options offered by The Conversation

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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