- André Biernath
- BBC News Brazil
image sources, Getty Images
In practice, the dose update process is more complicated than first thought.
A year and a half after the administration of the first doses, covid-19 vaccines must be updated to combat omicron subvariants, such as BA.1. BA. 4 and BA. 5.
They should be available between September and October 2022, according to what is expected by drug and pharmaceutical regulatory agencies such as Moderna and Pfizer, both producers of vaccines already approved and used on a large scale in much of the world.
“It is strongly recommended and necessary that we have new vaccines”, says pediatrician and infectious disease specialist Renato Kfouri, director of the Brazilian Vaccination Society.
In practice, the process of updating doses is more complicated than initially thought.
The main obstacle was the rapid and unpredictable appearance over the past year of new variants of Sars-Cov-2, the coronavirus responsible for the current pandemic. For example, when researchers were working on developing a vaccine to combat alpha and beta variants, the rise of the delta had already become a problem.
The good news is that currently available vaccines and which are given in three or four doses, depending on the age group and health conditions, continue to protect against the most serious forms of covid associated with hospitalization, intubation and death.
The BBC spoke to experts to understand the setbacks and possible solutions to increase people’s protection against covid-19 in the future.
essential steps
In December 2020, when the first vaccines were about to be ready, one of the most circulated information concerned the possible ease of updating doses.
“At first it was said that this process would be very fast, that in about 20 days we could have new vaccines,” recalls physician and epidemiologist Denise Garrett, vice president of the Sabin Vaccine Institute in the United States.
“As time passed, We saw that it was not quite that.”
The process for making changes to the original wording is not that complicated. In mRNA vaccines, like those from Pfier and Moderna, or in viral vector vaccines, like those from AstraZeneca and Janssen, it is enough to modify the sequence of genes that “teach” our own body to produce the protein S , a spike-like structure that sits on the surface of the coronavirus and attaches to cell receptors to trigger infection.
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Newer versions of the virus are increasingly infectious and able to evade the immune response.
Recall that the first generation of vaccines was developed from the “original” virus, detected in Wuhan (China) at the end of 2019.
The tip (S protein) is the part of the virus that has undergone the most genetic mutations as new variants appear.
The process of “Editing” the gene sequence in the vaccine is simple and can be done in the lab in a matter of days.
But it is precisely in the next stage where the biggest obstacles appear.
“Modified vaccines have to go through clinical trials to see if they work, if they elicit an immune response and if they’re just as safe,” says Dr Sue Ann Costa Clemens, director of Oxford-Brazil Vaccine. group in the UK.
“If all these results are satisfactory, we will enter the regulatory phase in which countries analyze the data and decide whether the vaccines will be available for use,” adds the specialist, who is also head of the Institute of Global Health from the University of Siena, Italy.
In the best case, if the process is done quickly, it takes at least a few months to complete. That’s not counting the time it takes to produce and distribute the millions of doses of the product.
The main problem is that the the coronavirus works at a completely different speed: Since the appearance of the omicron variant at the end of 2021, in a few months several sub-variants have appeared with even more infections and with the ability to evade the immune response.
In the first half of 2022 alone, the world saw BA.1 (the first omicron sub-variant) being followed by the BA.2 sub-variant and, recently, by the dominant BA.4 and BA.5 sub-variants .
image sources, Getty Images
Currently available vaccines protect against the most severe symptoms.
In addition to this lag, newer versions seem to have more ability to evade the immune response resulting from vaccination and previous covid infections. In fact, the number of people who are re-infected for the second or third time is increasing day by day.
But what will come next? What will be the future variant or sub-variant to worry about? Nobody knows the answer.
How to solve this equation?
We have both a short term problem and a long term problem. In the coming months, regulatory agencies and pharmaceutical companies must discuss how to speed up this testing and approval process to extend immunity of the people most susceptible to the effects of covid-19.
In this sense, the Food and Drug Administration (FDA) of the United States, seems to have taken a first step.
In late June, agency officials determined that the booster doses to be used in this country from autumn (late September for the northern hemisphere) they will need to have some sort of protection against sub-variants of ofmicron, preferably against BA.4 and BA.5.
Even before this announcement, pharmaceutical companies were already working on updating their products. For example, Moderna announced that it was testing a vaccine capable of protecting against the “original” coronavirus and also against the BA.1 subvariant.
The latest results published by the company, which have not yet been reviewed by independent researchers, indicate that the new version of vaccines they bend the production of neutralizing antibodies against BA.1 compared to older doses.
image sources, Brazilian Ministry of Health
In order to anticipate the strains that will predominate in each season, the virus must stabilize.
Pfizer is also making progress on an updated BA.1 vaccine, and early data the company has shared also indicates an increased immune response.
The two laboratories say they are working on specific formulations to extend protection against the BA.4 and BA.5 subvariants. In this case, it’s still at an early stage and previous results may still take a while to see the light.
Regardless of how this process will unfold in the coming months, there is a consensus around finding a way to reduce the lead of the virus in this race, so that the doses used in future vaccination campaigns are closer to the variant that is in circulation at that time.
“What we need is the coronavirus vaccination is something similar to what we currently have for the flufor which health authorities analyze and determine the strains likely to circulate most intensely in each season,” suggests Garrett.
“From there, it would be possible produce vaccines without the need for longer clinical trials and with the entire regulatory approval process“, To add.
However, for this scenario to become a reality, the circulation of the coronavirus will have to stabilize.
“We are facing an unpredictable scenario, in which we still cannot predict which variant will circulate in the coming months”, analyzes Kfouri.
Looking at the present with a view to the future
Experts understand that the use of bivalent vaccines, i.e. they protect against the “original” virus and also against the omicron variant, as proposed by the pharmaceutical companies, can help solve the problem in the short term. But the future of vaccination necessarily involves more global solutions.
“We have to change our strategy. There is no point in simply adapting vaccines to each new strain that appearssays Clemens, who is also a senior adviser to the Bill & Melinda Gates Foundation.
“We must develop solutions capable of protecting us not only from Sars-CoV-2, but from the whole family of coronaviruses, which have the potential to cause other pandemics in the future”, adds the researcher.
image sources, Getty Images
The creation of new vaccines is a very high risk and very expensive undertaking.
These projects, which include technologies such as nanoparticle-based vaccines or nose-applied solutions, are still at a very early stage and stronger results will not be seen for a year or two.
Garrett talks about the need to invest heavily in this type of research. “Vaccine creation is a very high-risk activity. The chances of a vaccine working well and being approved are around 7% on average,” he calculates.
“As we are talking about something very risky and very expensive, governments need to invest heavily in pharmaceutical companies. Because without incentive, these companies alone will not take the risk“, of.
To get an idea, the government of the United States has invested US DOLLARS$18.000 million in Operation Warp Speedwhich served as the basis for the development of vaccines and treatments against covid-19 and contributed to the creation of the Janssen, AstraZeneca and Moderna vaccines.
Until all these ideas are a realityit is important to follow the instructions of the health authorities and to be up to date with regard to vaccinations.
After all, as mentioned above, the doses we currently have continue to protect in most cases against the most severe symptoms and which can lead to hospitalization, intubation or even death.
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