What if I miss a dose?

SARS-CoV-2 vaccinesWhat to watch out for with the second dose of vaccine

Great Britain is currently suffering from a particularly severe corona pandemic. The number of infections is probably also very high because of a new virus variant that completely overloads hospitals. One element of the counter-strategy: the second vaccination has been delayed on the island for a week. Instead, more people receive their first vaccination and thus at least partial protection against SARS-CoV-2.

Meanwhile, there are many complaints in Germany about the hesitant start of vaccination. Nevertheless, the Standing Vaccination Commission (STIKO) warns against delaying the second vaccination. The STIKO chairman explained why this is so at a press conference at the Science Media Center.

Dlf science journalist Volkhart Wildermuth explains why it sounds tempting at first to give as many people as possible a first protection and to have the second vaccination if hopefully enough vaccine is available - because it seems that the effect after the second vaccination is perhaps even better .

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Volkart Wildermuth: The German Society for Immunology said in a statement and also in the Germany radio interview: If the second vaccination comes up to 60 days later, the effect may even be better. The immunologists refer to general experience with other vaccines.

But that is not enough for the chairman of the Standing Vaccination Commission, Thomas Mertens. Its mantra is: assured effectiveness, assured safety. And that is only possible with data, data, data. And they are still missing for changes to the vaccination schedule.

Ten to fourteen days after the first vaccination, most people develop antibodies and they are then somewhat protected. But after the second vaccination, you have 10 to 20 times as many antibodies in your blood and only then does this very high level of protection of around 95 percent take effect.

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The corona vaccine is currently not sufficient to immediately vaccinate all risk groups twice and thus provide maximum protection. Available data indicated that the interval between vaccinations could well be extended, said the doctor Christine Falk in the Dlf. But there are also risks involved.

Risk of possible resistance to vaccination

Uli Blumenthal: But isn't a little protection better for many than high protection for a few?

Wildermuth: First of all: the protection is really not that good at the beginning, various homes report that the vaccinated old people were still infected a week later.

That is why it is so important, despite the vaccination, to continue with all the protective measures in the homes, keeping your distance, FFP2 mask, rapid tests. And it could be that this phase of partial immunity, partial protection, is particularly problematic, said the virologist Florian Krammer from New York.

If someone is vaccinated and becomes infected, they have few antibodies and the virus continues to multiply anyway. But then it has the opportunity to adapt precisely to the antibodies produced by the vaccination. It could become resistant. Nobody can say how high the probability is. But the immunologist Harmut Hengel from Freiburg pointed out that the delayed vaccination in mumps has already led to the emergence of resistant variants.

If something like this happens with SARS-CoV-2, there would be a problem, because almost all vaccines use the spike protein. If, on the other hand, the virus becomes resistant to a vaccination, then it is probably also resistant to all others. As I said, whether that's likely or not, nobody knows. But the risk is there, which is why many experts see the delay in the second vaccination in England as problematic.

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Many could forget a second vaccination

Blumenthal: Is there nothing you can do to have more vaccine available?

Wildermuth: The STIKO of course also sees the problems and has softened the recommendation a bit on one point, one could say. In the approval, the minimum interval to the second vaccination is set at three weeks at BioNTech, at Moderna it is four. This distance is necessary in order to build up a first immune response, which is then strengthened and refined with the second syringe. But there is also a maximum interval of six weeks in the approval. The current recommendation specifically states that it is okay to wait that long.

Ultimately, that's not so far away from the proposal of the German Society for Immunology with the 60 days. But that would not be covered by the approval and the STIKO does not want to go beyond that. For reasons of legal liability and also to keep trust in the vaccination high.

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What you shouldn't forget: If the second vaccination is now handled variably, the vaccination centers will be faced with logistical challenges. And with the long waiting time, some people may forget that a second vaccination is due. Important: the vaccination must be completed with the vaccine with which it was started.

Many ways to use available vaccine more effectively

Blumenthal: Are there other ways to use the available vaccination doses more effectively?

Wildermuth: It is already permitted, wherever possible, to get six instead of the guaranteed five vaccinations out of a BioNTech bottle. There is also scope if people are naturally infected with SARS-CoV-2. A vaccination is then unproblematic.

But a single vaccination afterwards may be enough to get full protection. Studies are currently underway on this. And if someone becomes infected after the first vaccination, they will receive a second dose, so to speak, of course, then - as the STIKO recommends - the second vaccination can be dispensed with. These are more likely isolated cases, but that helps save vaccine.

What would do a lot with Moderna's vaccine would be to cut the dose in half. Sounds crazy at first, but the vaccine contains a lot more of the effective RNA than BioNTech's vaccine. The phase 2 studies show that even lower amounts trigger high antibody levels. But even that is only possible if the relevant studies are available and the approval is changed. So there are a number of ways to make more effective use of the available vaccine, but it doesn't just work that way, only when there is hard data.

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