Covid-19: Six things scientists want to know about vaccines

What are six things that scientists want to know about vaccines?

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Coronavirus vaccinations are expected to begin soon in several countries, including Cyprus and Greece. As millions of people around the world will be vaccinated for Covid-19, scientists will monitor the evolution of things.

Here are six key questions that scientists need to answer:

1. Vaccines prevent the transmission of the coronavirus and its spread Covid-19;

From the clinical trials of the three most advanced western vaccines to date (Pfizer / BioNTech, Moderna and Oxford / AstraZeneca), they all prevent the onset of symptoms of the disease in the majority of those vaccinated (thus protecting against getting sick when the virus enters in his body), but no vaccine can certainly prevent infection (ie it does not guarantee that someone will not catch the virus). This leaves open the possibility that some of those who are vaccinated may remain vulnerable to infection without symptoms, and therefore transmit the virus to others.

"The worst-case scenario is to have people walking around comfortably, but spreading the virus everywhere," said Stephen Griffin, a virologist at the University of Leeds in the UK. Pharmaceutical companies plan to study this very issue in the future, ie whether their vaccines protect against the infection itself. There is early encouraging evidence that vaccines may also reduce the incidence of asymptomatic infections - something that must be confirmed in the future.

2. How long will vaccine immunity last?

There is no quick way to answer how long the antibodies produced in response to vaccines will last, so it will be months or even years after the first vaccinations.

From this it will be judged how frequent the human infections with coronavirus will be. It will be important for public health authorities to monitor immunity in the long term and to know when it begins to weaken. To do this, they must, among other things, frequently test antibodies in the population. Keep in mind that there is a great variety in people's immune responses for a variety of reasons and that, after all, vaccines do not "work" equally well in all people.

3. How effective will vaccines be for the elderly and children?

Clinical trials of vaccines to date have not included a large number of groups such as the elderly, children and pregnant women. Therefore, it is currently difficult to estimate how well the vaccines will "work" in these and other subgroups of the population (eg in the obese). Evidence so far is encouraging that they trigger adequate immunity in those over 65, but there is no evidence for children and pregnant women (Moderna announced on December 2 that it would try the vaccine specifically for children). Statistics from a large number of vaccinated people will therefore be needed until scientists are convinced that there is no group of the population that is not adequately protected by vaccines.

4. How different will the effectiveness of vaccines be in practice?

All three most advanced western vaccines have achieved the basic minimum goal of over 50% efficacy and all seem safe, based on clinical trials to date. Scientists want to see how well each one "works" in practice, given that both (Pfizer / BioNTech and Moderna) are RNA vaccines, while the third (Oxford / AstraZeneca) is a DNA vaccine. Probably some kind of vaccine will be more effective in some groups of the population or it will be better not only to protect against getting sick, but also to reduce the possibility of infection with the virus and therefore its further transmission. The different costs and practical needs of each vaccine (transport, storage, etc.) should also be evaluated. A vaccine will probably be more suitable for the poorest countries. Of course, in this first emergency phase, according to immunologist Danny Altman of Imperial College London, "things are clear: one can grab any vaccine the government can buy."

5. Will the coronavirus be able to evolve to avoid vaccine immunity?

Some viruses, such as the flu, mutate, which SARS-CoV-2 does to a lesser extent. Scientists hope that the new coronavirus will not evolve in a way that will partially invalidate first-generation vaccines. But they are worried that mass global vaccinations could put tremendous evolutionary pressure on the coronavirus to mutate and produce a strain that escapes the antibodies produced by the vaccines.

"We have never seen a virus like this, under such pressure. "So we do not know how the coronavirus will react," said virologist Dr. Griffin. Therefore, scientists will monitor its gradual mutations and, if necessary, change the composition of vaccines, developing a new generation of vaccines Covid-19.

6. What about the safety of vaccines in the long run?

The scientists will monitor the vaccinated for any side effects, in addition to the harmless ones that emerged during the clinical trials. However, the experience of vaccines so far shows that serious side effects usually do not occur.

Source: RES-EAP