Booster dose of vaccines lowers the impact of omicron | Science

The new variant of the coronavirus, which is on track to be dominant before the end of the year, is making the third dose mandatory. Ómicron has been shown to be much more contagious than previous versions of the virus, also among those vaccinated. That means that, with a greater number of infections, the probability of a serious course of covid increases. But the first reports from universities and vaccine manufacturers, the latest from Moderna, show that a third prick raises the immune system’s defense levels.

Imperial College London (United Kingdom) published last week two reports on the impact of omicron. They have proven that the new variant better escapes the defense system raised by the immune system with the help of vaccines. These first data indicate that the efficacy of the two doses against contagion, especially if they were received months ago, drops significantly. Fortunately, the decrease in protection against a severe course of covid is much milder, remaining above 80%. Everything indicates that the amount of neutralizing antibodies in the blood is much lower (up to 4.5 times) than in the previous dominant variant, delta.

In this arms race against the virus, vaccine manufacturers are testing new formulations and dosages to deal with omicron. The Moderna company announced this Monday the results of a small trial that, although preliminary, supports the need for the third vaccine. Using blood serum from infected with different versions of the coronavirus, they have found that a third prick raises the specific neutralizing antibodies against the new variant up to 37 times. These types of antibodies are only one of the possible defenses that the immune system has, but they are key, since they prevent the virus from joining the cell and if it does, they neutralize both.

This third dose is, in Moderna’s case, 0.25 milliliters, half that of the first two. Although the health authorities have not approved it, they also measured the effectiveness of doubling it to 0.5 ml. So, the antibodies rose 83 times from pre-puncture levels. The rise of the defenses was observed 29 days after the third puncture.

Moderna has not acknowledged that omicron weakened the effectiveness of the double dose of its vaccine. But Pfizer and its technology partner, BioNTech, did so two weeks ago. They carried out a similar trial with those vaccinated with their inoculate, Comirnaty. The serum of those infected with the new variant and who had received only two doses showed a quantity of neutralizing antibodies 25 times less than that of those who carried the original virus. However, the good news is that those who had received the third dose had an antibody concentration similar to that of people infected with the original SARS-CoV-2 or pre-omicron variants and vaccinated only twice.

Pfizer President Albert Bourla said at the time that “although the two doses can still protect against severe disease caused by the omicron variant, it is seen from these preliminary data that protection improves with a third dose of our vaccine.”

“I think it will protect people during the coming Christmases and in these winter months, when we will witness the strongest pressure from omicron”

Moderna Medical Director Paul Burton on his vaccine

Both Pfizer / BioNTech and Moderna are running parallel trials to meet the omicron challenge. In some, whose preliminary results are those now announced, they study whether a third dose is enough to stop the most negative impacts of the new variant. But they also test new weapons. The first two, for example, already began with the first cases of omicron, the design of a specific vaccine for this variant. They think they could have it ready in 100 days. In addition, they test with specific formulations for each variant of the virus (alpha, beta, delta or combinations of both). These multivalents have also been announced by Moderna. His strategy, in addition to testing higher doses, is to test specific booster vaccines for delta and omicron. The investigation has already started with hundreds of volunteers.

Moderna’s medical director Paul Burton said in an interview collected by Reuters that it is now available is 1273, in reference to the scientific name of its vaccine, mRNA-1273. “It is highly effective and extremely safe. I think it will protect people during the next Christmas and in these winter months, when we will witness the strongest pressure from omicron ”, he continued. Before the new formulations arrive, Burton recalled that governments and authorities have the option of approving the increase of the current third dose to 0.5 ml. In their trials they have seen that it was safe, although they detected a slight increase in adverse reactions. The other option, which some countries are already taking, is to shorten the period between the second and third puncture, which is six months.

According to what was said by the director general of the World Health Organization, Tedros Adhanom Ghebreyesus, there will be no choice but to extend the third dose to the entire population and as soon as possible. “There is already consistent evidence that omicron is spreading significantly faster than the delta variant,” he told a news conference. He also confirmed what is already evidence: “And it is more likely that people vaccinated or recovered from covid can become infected or reinfected.” For her part, the executive director of the European Medicines Agency has acknowledged that there is still no consistent data on the degree of reinforcement offered by the third dose of the vaccines. But he also assured in an interview to the Financial Times that from the data that are arriving, although scarce and preliminary, “it is clear that there is a drop in effectiveness.”

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