Ômicron: what is known about vaccine efficacy against the variant

Preliminary research on the behavior of vaccines against omicrons brings good and bad news: the new variant of the coronavirus appears to have more ability to evade immunization, but so far data indicate that immunizers still largely protect against possible serious cases of Covid-19.

Furthermore, those who have already had the opportunity to take the booster dose seem to be better protected against the virus, including against the new variant.

The omicron is of concern because it has a much larger number of mutations than previous coronavirus variants.

On Wednesday (8/12), the companies Pfizer and BioNTech presented their own data, which are still preliminary, indicating that the vaccine’s protection actually drops drastically against the new variant.

However, they say, the booster dose of the immunizer would considerably increase the immune system’s defense against omicrons.

“Plasma from individuals who received two doses of the current Covid-19 vaccine had, on average, a more than 25-fold reduction in neutralization against omicron compared (with previous forms of the virus), indicating that two doses (from Pfizer) ) may not be sufficient to protect against omicron infection”, states a statement from the companies – noting, however, that “vaccinated individuals still seem to be protected against the most serious forms of the disease”.

The apparent good news is that Pfizer’s booster dose would regain that protection.

“According to preliminary data, the third dose provides a similar level of neutralizing antibodies against omicron than the two doses against (other forms of the virus)”, in addition to maintaining protection against more severe forms of Covid-19, according to two manufacturers.

The companies added that they are developing a specific vaccine against the omicron variant, to be delivered within 100 days, pending regulatory approval.

Study in South Africa

On Tuesday, a small study, still in the pre-print phase (ie, not reviewed by other scientists) carried out in South Africa — where Ômicron has been identified and has been moving rapidly — reached conclusions that point in the same direction.

From analyzing the antibodies of 12 people who received the Pfizer vaccine (half of whom had also been previously infected with the coronavirus and the other half had not), the researchers noted that the antibodies produced by the people were much less effective in preventing the infection against the omicron.

However, the perception of study author Alex Sigal, a virologist at the Institute for Health Research in Africa in Durban, is that “although I think there will be a lot of infection, I’m not sure it will translate into systems ( collapsing,” he told The New York Times. “My suspicion is that we can get (the situation) under control.”

The good news here is that the virologist initially feared that, in the face of such a mutated virus, vaccines would prove totally ineffective — but that didn’t happen.

Sigal added that it will still be necessary to further study the effects of booster doses of vaccines, but his suspicion is that “the more antibodies you have, the better you will do” against the new variant.

In addition, it is worth remembering that vaccines trigger an immune reaction that goes far beyond the production of antibodies — a reaction that is not measured by the studies listed here.

“Vaccines are still highly likely to protect most people against severe forms of the disease because they train the immune system much more than they do to produce neutralizing antibodies,” explains BBC science and health expert James Gallagher.

“T cells, which act on an infection, are better at dealing with variants as they attack different parts of the virus.”

“What is important to emphasize here is that immunity is not lost,” said, on Twitter, immunologist Letícia Sarturi, commenting on the data that the micron seems to escape more from immunization.

“Neutralizing antibodies work, cellular immunity will also work because memory T cells are not so easily ‘tricked’ by variants. They are activated by very small bits of the spike protein, so even if mutations do occur, T cells can respond because not all the bits and pieces of the protein have mutated. Variants are a threat to pandemic control, but variants will not completely compromise what we gain from immunization.”

booster doses

There is also another study that is still preliminary (and without peer review) and sponsored by vaccine manufacturers, which specifically evaluated the effectiveness of booster doses (in this case, those from Pfizer and Janssen) in 65 individuals.

While not specific about omicron, the study suggests that the additional dose of the vaccine “increases antibody responses in people who had been vaccinated at least six months before” with Pfizer’s vaccine.

However, researchers point out that the duration of this boost in immunity is still unknown.

It will still be necessary to carry out more studies on how these and other vaccines behave against omicron — and, also, how the booster dose can increase people’s protection.

For now, the WHO (World Health Organization) argues that the expectation is that vaccines will continue to be effective against omicron.

“We have highly efficient vaccines, which have proven effective against all variants so far, in terms of (preventing) severe forms (of Covid-19) and hospitalizations. There is no reason to believe it will be any different” with omicron, he told agency France Presse Mike Ryan, director of emergencies at WHO.

Even so, governments and scientists remain on the alert to monitor the effects of the omicron as it progresses.

“A large, sudden wave of the omicron can still cause problems, even if it only causes mild symptoms for most people,” explains reporter James Gallagher. “If the few who have severe cases of Covid-19 become infected with the omicron at the same time, it could put pressure on healthcare systems again.”