Bivalent COVID vaccines have now been in use for a few months

Vaccines have played a major role in mitigating the harms of the COVID pandemic since their deployment has begun a little over two years ago. They are estimated to have saved Tens of millions lives around the world.

The initial crop of COVID vaccines was designed to train our immune system to recognize the spike protein on the surface of the original strain of SARS-CoV-2 (the virus that causes COVID-19). But as we well know, since SARS-CoV-2 was first identified, it has continued to mutate and evolve into a range of distinct variants.

Some of these variants carry mutations in their genomes that can increase the ability of the virus to pass between people, evade antibodies produced by our immune system, or affect disease severity.

Omicron, the main driver of COVID infections worldwide right now, has more than 50 mutations in its genome and is highly transmissible compared to previous variants. Some of omicron’s mutations allow him to evade antibodies induced by previous infection, vaccination and antibody therapies.

Scientists therefore set to work designing and slightly adjusting vaccine formulations that would target not only the original strain of SARS-CoV-2, but also newer variants of the virus – omicron in particular. These are called bivalent vaccines.

Because they were based on the same mRNA technology used in first-generation COVID vaccines, they could be tested and approved fairly quickly. But now that we’ve been using bivalent boosters in the real world for a few months, we’re starting to gather evidence of their effectiveness against omicron.

mRNA vaccines: an update

Both Modern and Pfizer/BioNTech have updated their mRNA vaccines to provide broader protection. These vaccines contain small strings of genetic material called messenger RNA that instruct our cells to make copies of the coronavirus spike protein.

Once these advanced proteins are made, they are used to train our immune cells to recognize and kill SARS-CoV-2 if we are infected. Bivalent vaccines contain two types of messenger RNA molecules that provide the instructions for two different types of virus spike protein: one from the original SARS-CoV-2 strain and the other from omicron BA. 1.

A later update targeted omicron BA.4 and BA.5, seeking to help our immune system keep up with rapidly emerging omicron subvariants.

It was hoped that these updated bivalent vaccines would train our immune system to produce antibodies capable of protecting against omicron and future variants that may emerge.

Safety trial results indicated that both Modern and Pfizer/BioNTech’s bivalent vaccines were safe. All side effects were similar to those seen after vaccination with the original versions of these vaccines, such as pain at the injection site and fatigue.

Laboratory tests have also shown that bivalent vaccines trigger higher levels of antibodies against omicron compared to the original shots. Based on this evidence, these vaccines have received emergency approval in several regions, including WEthem UK and the EU.

In the UK, these bivalent vaccines have started to be given to clinically vulnerable people and adults over 50 in the fall 2022.

So how do they work?

A great study from the United States Centers for Disease Control and Prevention examined adults with symptomatic COVID between September and November 2022. It found that the use of a bivalent booster targeting the original virus plus the omicron BA.4 variant /BA.5 provided additional protection against symptomatic infection compared to a monovalent booster targeting only the original strain.

Other american studies showed that the risk of hospitalization was reduced by at least 38% in people who received a bivalent booster compared to those who received two or more doses of the original vaccines. In adults over 65, the additional protection was up to 73%.

Meanwhile, latest searches suggests that bivalent boosters will provide protection against emerging omicron subvariants. Serum samples from people who received the bivalent boosters containing BA.5 had better neutralizing activity against all omicron subvariants (especially BA.2.75.2, BQ.1.1 and XBB) than those who received one or two regular reminders.

An elderly man receives a vaccination. — Data on the efficacy of bivalent vaccines are promising.
Aleksandar Malivuk/Shutterstock

What does the future hold?

Evidence so far suggests that a booster with an updated bivalent vaccine is a safe and effective way to reduce the risk of serious illness and death from COVID.

Predict which variant will be nextand when or if an updated vaccine will be needed in the future is unclear.

But mRNA vaccines are perfectly suited for this because they can be Adapted fairly quickly to the latest variants of concern, and can be produced quickly. Their flexibility is such that plans are underway to test their use as personalized vaccines. in cancer patients in the UK.

Several other COVID vaccine approaches are being developed to provide broader protection against current and future variants. Some are designed to stimulate us T cells, a type of immune cell. Others are made of small nanoparticles containing fragments of the spike proteins of SARS-CoV-2 and several other related viruses.

Whatever the future holds, the data continues to show that regardless of type of booster usedVaccination is a safe and effective way to reduce disease transmission and protect against serious illness, hospitalization and death.