Sunday, September 25, 2022

Should you get a COVID-19 amplifier shot now or wait until fall? Two immunologists help weigh the options

While COVID-19 vaccines are still extremely effective in preventing hospitalization and death, it has become clear that the protection afforded by current vaccines diminishes over time. This necessitates the use of reinforcement shots that are safe and effective in strengthening the immune response against the virus and extending protection.

But when to get a first or second booster, and which shot to choose, are open questions. Many people find themselves unsure whether to wait for new, updated formulations of the COVID-19 vaccines or to mix and match combinations of the original vaccine strains.

SARS-CoV-2, the virus that causes COVID-19, uses its nodular nail protein to enter cells and cause infection. Each of the existing and emerging vaccines relies on the mimicry of the peak protein to activate the immune response. However, each type of vaccine provides the peak protein to the immune system in different ways.

As immunologists studying inflammatory and infectious diseases, including COVID-19, we are interested in understanding how the COVID-19 vaccine designs differ in the type of immunity it causes and the protection that results from it.

New divalent vaccines

Moderna and Pfizer-BioNTech, the two companies whose mRNA vaccines were the primary options for COVID-19 vaccination across all age groups, are both launching new vaccine formulations. An Advisory Committee of the Food and Drug Administration will meet on June 28, 2022 to evaluate the latest versions and to decide which ones are likely to be recommended for use in this fall’s booster shots.

Moderna’s new divalent vaccine mixes mRNA encoding the peak proteins of the original SARS-CoV-2 virus as well as the slightly different peak proteins of the more contagious omicron variant.

In early June 2022, Moderna said that in clinical trials, its bivalent vaccine surpassed the original vaccine strain, resulting in a stronger immune response and longer protection against the original SARS-CoV-2 and its variants, including omicron.

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Moderna later announced that its latest formulation is also performing well against the latest omicron subvariants, BA.4 and BA.5, which are fast becoming the dominant strains in the US Due to the significantly stronger immune response caused by the new shot, Moderna predicts that such protection could last a year and plans to launch its new vaccine in August.

The new Moderna amplifier may be available by autumn 2022.

And most recently, on June 25, Pfizer-BioNTech also announced results for its two new COVID-19 vaccine formulations: a bivalent formulation consisting of mRNA encoding the peak proteins of the original SARS-CoV-2 strain and the original BA. 1 omicron subvariant, and a “monovalent” version aimed only at the peak protein of BA.1.

The company’s preliminary studies have shown that both the monovalent and the bivalent vaccines produced antibodies that neutralized the newer omicron BA.4 and BA.5 subvariants, albeit to a lesser extent than the BA.1 subvariant. However, Pfizer’s monovalent vaccine produced better virus-neutralizing antibodies against the omicron BA.1 subvariant than the bivalent vaccine.

However, whether the differences in the levels of such antibodies seen with the monovalent versus bivalent vaccines translate into different levels of protection against newer omicron variants need to be determined in clinical trials.

Progress with the Novavax vaccine

Another vaccine formulation working its way to authorization is Novavax, a vaccine built with the peak protein of the original SARS-CoV-2 virus. The Novavax vaccine has the advantage of being similar to traditional vaccines, such as the DTaP vaccines against diphtheria, tetanus and whooping cough, or the vaccines against other viral infections such as hepatitis and shingles. The Novavax vaccine has been clinically tested in South Africa, the United Kingdom and the USA and has been found to be safe and highly effective with 90% efficacy against mild, moderate and severe forms of COVID-19.

An advisory committee to the Food and Drug Administration endorsed the Novavax vaccine in early June 2022. Now the FDA is reviewing changes that Novavax made during its manufacturing process before making its decision to authorize the shot.

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In Australia, the Novavax vaccine was recently provisionally registered as a booster for individuals 18 years and older. The company is conducting Phase 3 clinical trials to determine if its vaccine can be used safely and effectively as a booster in people who have previously taken mRNA vaccines.

When these new vaccines become available in the coming months, people will have significantly more options to mix and match vaccines to improve the duration and quality of their immune protection against COVID-19.

Novavax does not need to be frozen, so storage and delivery of the vaccine is much easier.

Mix and match

Until then, clinical studies have shown that even mixing and matching the existing vaccine types is an effective strategy for promotion. For example, recent studies suggest that when adults who were fully vaccinated with any of the original three COVID-19 vaccines – Pfizer-BioNTech, Moderna or Johnson & Johnson – received a booster dose with a different vaccine brand than the one they in their initial range, they had a similar or more robust immune response compared to enhancement with the same branded vaccine.

Vaccine mixtures have been found to be safe and effective in several studies. The reason why the mixing of vaccines can produce a more robust immune response goes back to how each of them presents the peak protein of the virus to the immune system.

When the SARS-CoV-2 virus mutates in regions of the peak protein, as was the case with each of the variants and subvariants, and tries to evade the immune cells, antibodies that recognize different parts of the peak protein can stop it in its tracks. and prevents the virus from infecting the body’s cells.

So whether you decide to get a booster shot or wait until the fall, for many it is encouraging to know that more options are on the way.

Nation World News Desk
Nation World News Desk
Nation World News is the fastest emerging news website covering all the latest news, world’s top stories, science news entertainment sports cricket’s latest discoveries, new technology gadgets, politics news, and more.
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