What is planned to do with the third dose of the Covid-19 vaccine

WHO urges those left behind to vaccinate more, but Israel has already started and pharmaceutical companies are presenting their data. Here's what we know so far

(photo: Paul Biris / Getty Images) Just a few months ago it was only a hypothesis, although not so remote, but today the question of the third dose of vaccine against Covid-19 has already become a reality . At least for some countries. For others, still waiting for the first one, a mere mirage, so much so that the opportunity to proceed with a new administration to those who had already completed the vaccination cycle has been criticized by the World Health Organization, both from a social and health point of view. , given the enormous disparity in the availability and distribution of vaccines.

The case of Israel

But someone, we said, has already started vaccinations with the third dose . This is the case of Israel, again, already pioneering mass vaccinations last year, which on July 30 - after a considerable increase in the number of new daily cases, with a surge that continues today - gave way to the administration of the third dose, now available for all over 30s.

More than one and a half million people have already received it, and the first data on its efficacy, albeit preliminary, are also beginning to spread. It refers to an efficacy against infections of 86% compared to the double dose. But on the third doses - which we also talk about, especially for the most fragile populations, with recalls expected about six months after the end of the vaccination cycle - there are different data that have been accumulating in recent days. And they are precious, especially now that we are preparing for the autumn season, for the reopening of schools.

The new data on additional doses

Are those that come from companies (not yet published) and are mostly indirect data, which, rather than looking at the effectiveness of the recalls, focus on the 'analysis of the immune responses induced by additional doses. A few hours ago, for example, almost simultaneously, the data relating to boosters with the Johnson & Johnson vaccine (of which at the moment a single administration is planned) and Pfizer / BioNTech arrived.

In the case of Johnson & Johnson, the first data report an increase in the antibody response against the coronavirus spike protein of nine times compared to the values ​​measured almost a month after the first dose, so much so that the company is working to imagine using its vaccine also as a booster approximately eight months after the first administration. More details are not found in the corporate press release, but the data released seem to concern just 17 people, cites the New York Times, who received the second dose six months after the first.

There are instead about 300 people included in the analysis released for Pfizer / BioNTech's mRna vaccine. Neutralizing antibodies (note: against the wild-type form of the virus) more than tripled one month after the booster dose, compared to the numbers observed one month after the second dose. Enough to ask the regulatory authorities to approve the use of the third dose of the vaccine (now reserved only for particularly immune-compromised patients).

The duration of vaccine protection

The discussions, again partially open, on the usefulness of the third dose, essentially concern the question of the duration of immunity to the coronavirus, as we said. A question that is far from clear, both for the protection offered by natural infection and that of vaccines, but which would seem to indicate a duration of the order of a few months. Precisely this expected decrease in protection over time, which could be countered by the addition of an additional dose of vaccine, is the main reason given, among others, by US public health experts, when they announced the start just a few days ago. starting next September 20, eight months after the second dose (we are talking about mRna vaccines).

The fear is that, even if vaccines continue to be effective against severe forms of the disease, things could change in the months to come, especially, they write, “among people at high risk or among those who have been vaccinated in the early stages of vaccination campaigns. For this, we think that a vaccine booster will be necessary to maximize the protection induced by the vaccine and extend its duration ”. To reiterate that vaccination protection wanes over time are also the results from the Zoe Covid Study, which collected data worldwide in real time via the app, recording vaccine dates and the results of tests for the coronavirus, carried out during the spread of the variant. delta in the UK. The results indicate that protection increased from 88% at one month after the second dose to 74% after six months for the Pfizer vaccine, and from 77% after one month to 67% after five for the AstraZeneca one.

The solution, where recommended, may not necessarily be a third dose, but a "half dose". It is one of the possibilities being evaluated in Great Britain, reports the Guardian, to meet both the possibility of thus extending vaccination protection, and saving doses to be allocated to populations that are still mostly discovered. That the discussions are in progress, the European Medicines Agency (EMA) confirms to Ansa, explaining that it is not clear when and to whom it will be necessary to administer a booster dose, while admitting that it is something to be prepared for.




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Topics

Israel Health United States Vaccines Coronavirus vaccine Johnson vaccine & Johnson Vaccine Pfizer BioNTech globalData.fldTopic = "Israel, Health, United States, Vaccines, Coronavirus Vaccine, Johnson & Johnson Vaccine, Pfizer BioNTech Vaccine"

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