These are the health options to immunize more population with a dose of the COVID vaccine


Publication: Tuesday, April 20, 2021 11:09

This Tuesday, the public health committee will discuss the possibility of delaying the second dose of vaccination for certain groups to ensure the first puncture of the most vulnerable people. In this way, as indicated by the Executive, the vaccination of priority sectors could advance, knowing that a dose already generates a noticeable degree of immunity.

laSexta was given access to the proposal, which essentially offers three options: the first is to keep everything as is, according to the vaccine insert (the second injection should be given “three weeks” from the first). The second is to increase the vaccination interval for those under 79 years of age. And, in this case, regions can choose between two options: on the one hand, delay the second dose to 6 weeks; that is, twice the current amount, and on the other hand, take it even longer, up to 8 weeks.

And the third possibility is to expand the range of the population to which the second dose is delayed to those under 69, with also the possibility of choosing the interval between 6 and 8 weeks (the AstraZeneca vaccine will also remain at 12 weeks).

Here are the options that the Commission will vote on this Tuesday:

1. Continue the separation of the second doses in the vaccination with the mRNA vaccines as indicated in the current vaccination strategy (21 days for the Pfizer vaccine and 28 days for the Moderna vaccination).

2. Increase the dose separation interval for vaccination of cohorts of people under 79 years of age:

a) 6 weeks

b) 8 weeks

3. Increase the dose separation interval for vaccination of cohorts of people under 69 years of age:

a) 6 weeks

b) 8 weeks

Why delay the second dose?

In its proposal, Health argues that, given the current epidemiological situation, which “could indicate an increase in the number of cases”, it is considered “important to vaccinate as soon as possible as many of the most vulnerable people as possible”.

Likewise, the entity insists on the fact that in the majority of vaccinees, the first dose is the one that generates the most effect in the short term. They also point out that, “in general”, drug companies only specify minimum time intervals, but not maximum. In other words, the negative results would be appreciated by reducing the time, not by increasing it.

However, the document itself also admits of some inconsistencies. Especially when it comes to clinical trials of vaccines: it’s true that Pfizer and Moderna (the injections with the second dose being delayed) have tested intervals of up to 42 days (the 6 weeks the document says) . But this was achieved in 7% of participants in the case of Pfizer and only 2% in that of Moderna. In other words, according to these data, studies are lacking to confirm its effectiveness.

It was precisely this point that led the EMA to prevent these changes. Thus, according to the agency, the ideal is not to skip the deadlines: “Currently, there is no clinical data on the effectiveness of the vaccine when it is administered beyond the intervals used in the clinical trial ”, insists the European regulator.

In any case, beyond the recommendations of the EMA, there are already precedents for this change. Germany, Denmark, France and Italy are already betting on a 6 week window for mRNA vaccines, while Finland is extending the time window to 12 weeks for any vaccine.

In addition, there are several studies that support the effectiveness of single dose setting. These are the cases of Israel, Canada, the United States or the United Kingdom, where data showed that after the first puncture, an immunity of almost 80% would be achieved. Now, this new change will enter the debate, and this same Tuesday, the criteria will be decided: follow the recommendation of the EMA or rely on this new evidence.

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