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Will a third booster dose against the coronavirus be necessary?

Just because Pfizer wants to offer a third booster dose of the coronavirus vaccine it does not mean that this is necessary. In fact, international health authorities say that the two doses appear to be sufficient, for now.

Worldwide, experts are studying the effects of vaccines to determine if a third injection is necessary. At the same time, voices proliferate calling for more people to be immunized, arguing that the threat of the new variants would not exist if more people in the United States and the rest of the world were vaccinated.

“If people want to stop hearing so much about the new variants, what has to be done is that all countries have access to vaccines’‘said Jennifer Nuzzo, a public health specialist at Johns Hopkins University.

Here some questions and answers about the possible need for a third vaccination:

-Why do you debate about a third dose?

US health authorities have long claimed that people may one day need an extra injection, as do many other vaccines. That is why multiple studies are underway to test different possibilities: a third simple dose, a vaccine from a brand other than the previous two doses, or a vaccine specially designed to protect against the new variants.

However, last week Pfizer and its German partner BioNTech announced that in August will request authorization from the US health authorities for a third dose in order to boost the production of antibodies and thus protect the body from new variants.

The companies did not disclose scientific data and the US authorities responded emphatically that no further doses are needed for now and that it will be the government, not the pharmaceutical companies, who will decide if that changes.

The World Health Organization declared Monday that not enough evidence that a third injection is necessary. He also asked that surplus doses be donated to poor countries instead of being used to improve the immunity of wealthy people.

-The protection of vaccines

An analysis by The Associated Press last month found that nearly all coronavirus deaths in the United States They are from people who were not vaccinated.

In recent weeks, infections and hospitalizations have rebounded due to the spread of the delta variantBut the Centers for Disease Control and Prevention (CDC) point out that this is happening in the least vaccinated areas of the country and that there are enough doses there for people to inoculate.

There is no perfect vaccine so it is possible for someone fully vaccinated to contract COVID-19, but these cases are usually very mild. Experts are studying the incidence of this type of infection to assess whether it is necessary to offer a third injection to boost immunization.

So far the news is good: The first to be vaccinated in December and January do not appear to be more susceptible to contracting the disease than those who were inoculated more recently.

Do the new variants influence?

No, scientists are also studying whether overall immunity is declining among vaccinated people. If it decreases a lot, a booster injection may be necessary.

Antibodies tend to disappear over time. This is normal, since the human body does not need to be in a state of maximum alert all the time.

However, antibodies are not your only method of protection. By the time they subside, the body has generated other defenses like B cells, which when the body is attacked “explode and start dividing like crazy” to create more antibodies, explained University of Pennsylvania immunologist Scott Hensley.

Another defense is T cells, which kill infected cells and thus prevent the disease from worsening.

The most recent studies suggest that the antibodies are not as effective against the delta variant as they are against previous versions of the coronavirus, but that they continue to protect. The fear now is rather due to the possibility of future mutations that they are immune to current vaccines, something that can only be avoided if infections are stopped everywhere.

-How’s the fight against the Delta variant going?

The most recent data from England, Scotland, Canada and Israel show that the most commonly used vaccines in Western countries still offer a good level of protection. A study in Great Britain, for example, showed that two doses of Pfizer’s vaccine protect 96% against hospitalization in the case of the delta variant and 88% against symptomatic infection.

In Israel, preliminary results of a study indicate that protection against a mild delta variant infection is slightly lower, at 64%, but that protection against serious infection is still quite high.

There is less information on the performance of other vaccines against the delta variant. Thailand announced a few days ago that health professionals who received two doses of a Chinese vaccine will receive a booster dose of AstraZeneca.

– Is it possible that some need a reinforcement and others do not?

If possible. Israel just delivered third doses of the Pfizer vaccine to transplant recipients and other patients with weak immune systems, because those taking immune-suppressing drugs don’t assimilate vaccines – not just COVID-19 vaccines as well as healthy people. .

France has already delivered a third dose to immunocompromised people. And while it has not yet been approved in the United States, some transplant recipients have requested a third dose to bolster their protection.

It has not been shown yet whether a third dose really helps and, if so, who will need it and when. The first large-scale study of the subject is currently underway in Norway.

AP Agency

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