Do we need 2 doses of the corona vaccine?

In several Western European countries, people are beginning to wonder about the slowness with which the vaccination process starts. Also in Belgium. Politicians are finding it increasingly difficult to explain to the population why, compared to Germany, the United Kingdom, the US and especially Israel, we are failing to get the vaccination process going.

After the fiasco of the mouth masks (first unnecessary, then indispensable) and the corona tests (3 to 4 days waiting for the results), Christie Morreale (PS), one of our 9 ministers of Health, had to convince the Belgians on LN24 on Monday morning “We are not slow”. “It’s a false assessment,” Morreale replied to a viewer’s question. According to her, it has been agreed in agreement with the residential care centers to give the staff who have been overburdened for months a week of vacation. That before starting the vaccination on January 5.

According to the minister, Belgium will be able to vaccinate 40,000 people per week from Tuesday, January 5, based on the 87,000 doses made available by Pfizer. So 2 doses per person.

Are those 2 doses necessary?

But are those 2 doses necessary? Under pressure of circumstances, various countries are examining whether it is not better to vaccinate a larger part of the population once than a smaller part twice. In other words, isn’t it more interesting to vaccinate 80 percent of the population once than 40 percent of the population twice? In fact, the Americans are considering giving people between the ages of 18 and 55 only half a dose twice. That would, according to the person in charge Operation Warp Speed produce an almost identical result.

In mid-December, epidemiologist Michael Mina and socilologist Zeynep Tufekci had already raised the issue in an opinion piece in the New York Times.

Moderna’s vaccine is said to have an effectiveness of 92 percent with one vaccination, against 94 percent for two vaccinations. Pfizer-BioNTech’s would maintain an effectiveness of more than 80 percent with a single inoculation. The AstraZeneca vaccine further strengthens this path. Those who get vaccinated once would be 70 percent protected for 12 weeks. A similar percentage as when one is given 2 doses.

Second injection prolongs immunity

However, the above percentages do not represent the full picture. In the French newspaper Le Monde, immunologist Jean-Daniel Lelièvre says that the second vaccination is precisely intended to make that immunity last longer. At present, he says, there are no indications that a single dose offers the same protection over time. However, this is a crucial factor in achieving group immunity, which is part of the long-term goals.

So one has the choice. Or more people are vaccinated who then remain immune for a shorter period of time. In other words, fewer people are vaccinated who then remain immune for longer.

None of the three aforementioned vaccines is based on a single vaccination, precisely because the second vaccination makes the difference. The other vaccines, which are still under development, could possibly generate the same effect with a single dose. But it is not that far yet.

Will emergency break the law?

Now that various countries are tightening their lockdowns again, there is a danger of the need to break the law. If it is not possible to stop the increase in hospital admissions, it will be necessary to opt for a one-off vaccination. Not an optimal solution, but an emergency solution.

Meanwhile, Michael Mina and Zeynep Tufekci propose to study the infection rate of the people who took part in the clinical trial, but dropped out prematurely – after an initial vaccination. If they were not infected, that is no guarantee. But if they did become infected, we know that a single vaccination is not the solution.


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