Is it time for a new generation of Covid vaccines?

Analysis: The current shot may be updated soon to target new variants rather than ancestral stocks.

To Sina Crack Shank, University of Manchester

More than two years have passed since the pandemic occurred, SARS-CoV-2The virus that causes Covid-19 continues to challenge us. Its ability to mutate rapidly has seen the evolution of increasingly infectious variants that are getting better by hiding from our immune response.

Vaccines are a major achievement in modern science and have played an important role in reducing the worst effects of Covid. But is the vaccine we can currently deal with the latest Covid variant?

All current Covid vaccines are genetic components, or DNA sequence, Of the original ancestral strain of SARS-CoV-2. Most of these vaccines target peaplomers. It is part of the virus and attaches to and invades cells.

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RTÉ Radio 1 Today With Claire Byrne, GP Denis McCauley, Nuala O’Connor on Possibility of Fall 4th Round Covid Vaccine

Vaccines work by allowing immune cells to initiate a targeted response to spike proteins, including the production of antibodies known as neutralizing antibodies. These prevent the virus from invading our cells and help other immune cells find and destroy the invaders of the virus.

However, SARS-CoV-2 is a slippery customer, Spike protein.. That is, these vaccine-induced neutralizing antibodies are less effective than before.

Do new vaccines need to target mutants?

The idea of ​​vaccination against mutant strains rather than ancestral strains is gaining momentum. This is not a new concept in vaccine development. For example, annual influenza vaccination targets circulating variants.

One approach is to create what is called a “divalent” vaccine that targets pesplomers. Omicron (BA.1) and ancestral stocks. modern We are currently testing this option in a human study that combines Phase 2 and Phase 3.For data that has not yet been peer reviewed, this result is about Double increase In neutralizing antibodies against BA.1 compared to the original Covid vaccine.I’m watching other Moderna trials A combination of different divalentsIncludes vaccines targeting promising ancestral and beta strains.

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RTÉ 1’s Nine News encouraged people over the age of 65 to get a booster vaccine as Covid cases increase.

Pfizer Also released Test data About booster candidates specially tuned for BA.1. According to the company, this represcription elicited a better immune response to BA.1 than that produced by the original Covid vaccine.

So do we need to invest in these new vaccine candidates?The US Food and Drug Administration I think so, as I recently approved the use of these Omicron-specific shots later this year.

However, investing in and deploying new vaccines is not cheap and there are important questions that need to be addressed. As we know, SARS-CoV-2 is constantly changing and changing. Delta stocks became dominant worldwide less than a year ago, before which there were alpha and beta stocks. So are the Omicron variants suitable for targeting? Will they be dominant a year from now? do not know.

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Starting this week at RTÉ Radio 1, ESRI’s Shane Timmins discusses how the public’s attitude towards Covid has changed.

There are variations even in Omicron strains. The BA.1 mutants targeted by these new vaccine candidates have recently been BA.4 and BA.5.. BA.4 and BA.5 variants are more resistant to neutralizing antibodies, usually 3-fold or 4-fold. BA.1.. So the question is, if Omicron becomes widespread, will these Omicron BA.1 vaccines work better against BA.4 and BA.5 than the original vaccine?Data that have not yet been peer-reviewed suggest that bivalent vaccines may be a little Better From the original vaccine.

However, recent data show that Omicron infection does not produce strong immunity and is characterized by low levels of immunity, making Omicron a poor candidate for vaccine. Neutralizing antibodyIt needs to be higher and more persistent to prevent rapid reinfection. this is, Explain why many of us have caught Covid so many times.. If the same is true for vaccine-induced immunity to Omicron, then Omicron-specific vaccines may not be a worthwhile investment.

Other strategies

None of this means that you should stop looking for long-term preventive vaccines. However, there is probably room to focus on different strategies. Two exciting roads are emerging.

Initially vaccination Vaccines that target other parts of the more stable viral structure, or vaccines that target multiple parts of the virus. This may not be a vaccine that can completely prevent infection, but it may be more durable than current vaccines.

Another method involves leveraging the ability to neutralize nasal antibodies. And throat Target SARS-CoV-2 at the entry point. Vaccines that produce neutralizing antibodies in the nose and throat may block the virus’s pathway because these antibodies create a barrier that prevents the virus from entering the body.Trial research Nasal vaccine These are still in their infancy, but look promising.

Where does this leave us now? The ideal vaccine candidate induces long-lived neutralizing antibodies and provides lifelong immunity. Instead, in the case of Covid, we learned that the immune system needs boosters to supplement these neutralizing antibodies and increase the number of memory cells that support immunity.

Studies show that Covid vaccination and subsequent infections Immune monthBut this was before Omicron. Immunity.. Many of us have minimal neutralizing antibodies against Omicron.

Probably another variant of autumnWith the fear of Bad flu seasonIt seems wise to embark on a much wider fall booster campaign than the spring campaign.This means it’s not just about targeting 65 years and older and other high risks As currently planned, we will extend our qualifications to the younger age group.

The important thing is that you need to reach people who are not fully vaccinated, so your campaign should include targeted community education. This should be done in parallel with other mitigation strategies, such as wearing a mask, to keep us safe and to be able to live with Covid.

Sina Crack Shank Is a professor of biomedical sciences University of Manchester..This article was originally published by conversation..

The views expressed here are those of the author and do not represent or reflect the views of RTÉ.