What's in a vaccine shot

Biontech vaccineThe time interval between the first and second vaccination

Update: Stiko now recommends an interval of six weeks between the first and second vaccination dose for the two approved mRNA vaccines from Biontech / Pfizer and Moderna. The recommendation was updated on the basis of new efficacy data. The individual protective effect is very good. It also allows more people to receive a primary vaccination, which is expected to have a positive effect at the population level. *

The Biontech / Pfizer vaccine is not only in short supply in Germany. In Denmark, given the limited amounts of vaccine available, vaccine doses should be administered up to six weeks apart. In this way, more people should receive at least one first vaccination in a shorter period of time. Britain even wants to allow up to twelve weeks to elapse between the two vaccinations. In Germany, too, it is being examined to postpone the second corona vaccination in order to be able to give the preparation to more people in a timely manner.

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The German Society for Immunology has published a statement according to which you can wait a bit before administering the second vaccine dose. Professor Christine Falk from Hannover Medical School is President of the German Society for Immunology.

Ralf Krauter: How long could the second injection be delayed?

Christine Falk: It was important to us that the time frame is not arbitrary. You need the second vaccination, and we have said that from the data and also from the animal experiments you can say up to two months, so the 60 days until a vaccination success is also guaranteed come with the second dose in any case a real protection against the disease and ideally against the infection can take place.

Second vaccination up to 42 days later

Herbs: And that applies to both mRNA vaccines, both from Biontech, where it is actually assumed that the second shot should take place after three weeks, and also to the Moderna vaccine, which could now probably be officially approved in today Europe, where it has so far been assumed that the second shot would have to be fired after four weeks.

Falk: Exactly, that's the admission. If you say now that we can possibly use the window to provide more people with a primary vaccination, then the question is, how long do you have a very reliable indication that it will still work. We said, based on the data we had, up to 60 days. What has happened now since yesterday is that the European approval authority EMA has said, based on the data that is available to those who are but not public, who really have the detailed study data, that the period they specify is for the Biontech- Vaccine even up to 42 days. That means what was communicated to us and what the stipulations of the Standing Vaccination Commission and the PEI were, these 21 plus-minus three, and then for Moderna, if the approval is given, it will be 28, but the European authority already has said, on the basis of the data that you have in detail, 42 days, is the framework that is even covered by the approval.

Because this was not communicated that way, you can actually say that you are even within the approval range if you go up to 42 days. That will be the EMA - there are already reports today that this will be published, and we will see how the PEI and the Standing Vaccination Commission will then comment on it. 42 days, if you agreed on these, you would have already gained a lot. You don't want to arbitrarily extend the period because then so much slips - from logistics to the question of how motivated people are to actually get a second vaccination. It is very important to tell them that you need the second vaccination, the second shot, there is no way around it.

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Anyone under 60 who has first received the corona vaccine from Astrazeneca should receive a different preparation as a second dose. The infectiologist Marylyn Addo thinks this makes sense: Although the data situation is still thin, there is a lot to suggest that this approach is safe, said Addo on April 16, 2021 in the Dlf.

Second vaccination is important for strengthening the antibodies

Herbs: That is, you have just anticipated it, yes, also an argument by critics, among others also put forward by Anthony Fauci from the USA, the quite famous virologist. He says there is a great risk that the second vaccination will be forgotten if the interval between the first and second injection is so long, and that increases the risk that a significant number of people will not achieve long-term protection because of the so important one Booster effect, which stimulates T-cell immunity, then fails. Is that true?

Falk: Most of Tony Fauci's statements can be signed as they are, and these are exactly the same. It is exactly like that. There are few vaccinations where you don't need that, but especially for mRNA vaccines, where we don't know whether one would be sufficient, you have to go the safe way. That's why he is absolutely right when he says we need the second prick and this boost vaccination, not only to activate the T cells as real memory cells, but the antibodies can also improve again. The ingenious thing about the immune system is that it recognizes the target structure very precisely, in this case this spiky protein from the SARS-CoV-2 virus, and this quality of the immune system should be used, that is, trigger the best antibodies and the best T cell response. And that is what you get with this second vaccination, that's why you need it. It cannot be pointed out enough, the second is very, very important.

Herbs: A second argument from critics of this, let's call it deferral practice, is that if many people are initially vaccinated only once, SARS-CoV-2 has ample opportunity to mutate, in such a way that it might become immune to the vaccine. Is that a serious risk?

Falk: The mutations are always an issue. In the case of the SARS-CoV-2 virus, it is quite a good thing that it has a proofreading polymerase. That is technical jargon, but translated it means that it checks its own gene sequence over and over again.

We have to get through the next three months

Herbs: A built-in bug fix, actually.

Falk: Exactly, a built-in bug fix. And that's a good start. It mutates away, we have seen that with this variant from England and South Africa, that is, the virus naturally always tries to escape the immune response by deceiving and camouflaging. In this respect, it is correct that you need a good immune response so that you can also eliminate the virus and not trigger or provoke variants. This is also an argument for the fact that you definitely need two vaccinations and that you can't just somehow extend the period backwards. In this respect, the objection is justified, but it is not to be expected that we will now exert selection pressure with the few individuals who can be vaccinated. That is just not enough.

Herbs: The current recommendations of the Standing Vaccination Commission state that the completion of the vaccination series for people who have already received the first of the two necessary vaccine doses has priority over the start of vaccination for new people who have not yet received a vaccination. Do you advocate changing this very clear requirement soon?

Falk: This requirement comes from a time when we in Germany could not yet know how many cans will be available and when, and to that extent it was perfectly placed. The discussion arose from precisely this, one could call it a relative deficiency, and there I would definitely not want to anticipate the STIKO. It is in fact the discussion whether it would not be a sensible measure to give more people this first vaccination. Once we have secured the supply of vaccines, as I said, there is no need to discuss any further, then we will have enough doses at the regularly approved time. The only question is, how do we get over the next three months? It would be worth considering - I am very careful, deliberately very careful - whether the number of people who have at least already received the first vaccination should be increased immediately within this ideally 42-day period, at the latest 60 days catch up on second vaccination.

Statements by our interlocutors reflect their own views. Deutschlandfunk does not adopt the statements of its interlocutors in interviews and discussions as its own.

* We have updated the post to prevent misunderstandings. The EMA made its recommendation only after the interview.