The Enigma Of Immunity Against Covid: These Are The People

The enigma of immunity against Covid: these are the people who will have to be vaccinated every year

Although the data seems to indicate lasting immunity, there are population groups that will need a periodic booster.

A nurse prepares to administer an injection to a person at the Wanda Metropolitano.

In a kind of Stockholm syndrome of the pandemic, we all seem to assume the need for a annual periodic vaccination to keep SARS-CoV-2 at bay. In fact, the European Union announced two weeks ago the acquisition of 1,800 million doses of the vaccine from Pfizer and BioNTech for the years 2022 and 2023, in an assumption of what is to come: an annual booster injection, as in the flu.

However, the data still offers many uncertainties in this regard. After all, the number of reinfections is minimal (30 documented cases and about 2,000 possible out of almost 150 million infections worldwide), even in the case of new variants such as the British one. What’s more, cases of people who have been reinfected have generally been mild or moderate in nature, although there is one recorded death from reinfection.

It is true that there are mutations, such as the South African and Brazilian ones, that seem to evade the immune response triggered by previous infections, and it has been observed that the level of antibodies decreases months after infection: one study determined an average degradation of 6 % in the three months after infection, a percentage that rose to 39% in people over 75 years of age. However, it has not been shown that this implies re-infection.

The experts do not see it clearly. “The coronavirus is not the flu, it is not mutating in the same way,” he points out Rafael Orti, president of the Spanish Society of Preventive Medicine, Public Health and Hygiene.

“The mutations do not seem to be greatly affecting the prognosis, they do not produce the disease because the antibodies stop them, although in some variants it seems that they do affect.” For this specialist, “it is foreseeable that it will happen as in other coronaviruses: there are four that have affected us for many years, but they cause slight colds.”

A rhythm ‘doped’ of mutations

In fact, a recent study found that the ability of coronaviruses to mutate is much lower than that of influenza viruses: 6 mutations per year for every 100,000 nucleotides (the molecules that make up DNA) compared to 25. In the case of SARS-CoV-2 it is somewhat higher, 10 nucleotides, but this is because, at present, it is very expanded.

The authors of this jobpublished in the scientific journal Virus Evolution, conclude that it is more than likely that, due to this ‘doped’ rate of mutation, the vaccines against Covid-19 will have to be updated with some frequency in the coming years but that, after the pandemic stabilizes, the future vaccines will be effective for more time.

Ortí sees this scenario as reasonable and indicates that only in cases where immunity is altered can there be problems. “People of 80 or 90 years who have been given the two doses and are losing immunity and vulnerable people” such as the immunosuppressed. In fact, the latter (people who have undergone organ or bone marrow transplants, with cancer, HIV or on hemodialysis) are included in the priority vaccination groups of the national strategy against Covid-19, regardless of their age. .

The case of the Spanish vaccine against Covid-19

match your words Joan Carles March, co-director of the Andalusian School of Public Health, who admits that annual vaccination “is a possibility, although we do not have the elements to say so for sure. It is good to anticipate on the part of the European Union and that there is a preparation in that sense”, he considers, “but the most important thing is that all populations are vaccinated”.

And remember: the Spanish vaccine, “which is sterilizing and makes it possible not to infect anyone, will be available in 2022. Why is work still being done on it? It is believed in the possibility that it is still necessary to be vaccinated.”

March does not forget the social conditions and indicates that, in addition to chronic patients, there are groups in low socio-economic situations and social exclusion, who have shown greater vulnerability to the pandemic. “Covid-19 has affected more populations with more social and economic precariousness, and these are people who will not have to be vaccinated until at least October ”.

TTaking into account that current vaccines are not sterilizing (that is, they do not prevent transmission of the virus, only severe disease), it is possible that we have virus for “a minimum of two or three years”, but there is something that we are aware of. we must forget: “The reality is that this virus is unpredictable, and given that unpredictability it seems difficult to say how long it will last.” When in doubt, better prevent.