Hybrid Immunity – Vaccinated and recovered

It was initially surprising that a vaccine injected into a muscle also works locally in the nose and throat, where the coronavirus enters the body. If an infection occurs after a vaccination, this local immunity is stimulated very well, according to Wyler. A “hybrid immunity” occurs. Of course, this can also occur the other way around, i.e. through the combination of infection and subsequent vaccination. According to several studies the interaction between vaccination and infection is particularly important. [**]-

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The interview in full:

Kathrin Kuehn: So many people getting infected now. Many, too, who actually took great care to avoid this. Let’s assume that those affected are well vaccinated, i.e. boosted, what do you say in such cases?

Emanuel Wyler: The vaccines we have against Sars-CoV-2 are very effective and efficient. Of course there are exceptions, especially in the case of old people or those with a weakened immune system, but it is also the case that we now have treatment options. For all other people who are now vaccinated, there is actually no longer any particular concern about having a serious illness or long-term consequences like this Long Covid after a Sars-CoV-2 infection.

Kathrin Kuehn: And then it is also the case that an illness caused by vaccination is also, yes, I would say, a way to build up good immunity in the long term, hybrid immunity, as it is sometimes called. What happens there?

Wyler: What is important to know is that our immune system is not exactly the same everywhere in the body. We also have what is known as local immunity, which means an immune system that actually only works in the nose and throat, and of course when a virus like Sars-CoV-2 enters our body through the nose, it is particularly important that this local immunity is also effective. That’s not the case with a vaccine that’s injected into the muscle, and it was actually surprising last year to see that these RNA vaccines can also stimulate local immunity in the nose and throat.

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More on the topic of corona vaccination

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bold: That was the moment when we thought that the vaccines might also protect against transmission to a greater extent.

Wyler: Exactly. That was a really positive surprise. Unfortunately, this protection, this local protection in the nose and throat, does not last very long. There were studies last year that showed that it decreased significantly after two to three months. And that is also the effect that after a few months the vaccination is no longer as effective against any infection.

If an infection occurs after the vaccination, then this local immunity is actually stimulated very well, because then there is an infection in the nose, which means that this local immune system is then also prepared and is then in a better position next time the virus comes in to catch it again.

Risk assessment also speaks in favor of vaccination at Omikron

bold: That means I can generate this immunity on the mucous membranes, which could then protect me from infection, but at the same time I have ensured through the vaccine that I am protected to a certain percentage from a serious illness, so a comfortable starting point for working out this immunity.

Wyler: Exactly, because when you have the vaccination, then the immune memory is there, and of course the virus gets in your nose, it spreads a bit, but after about three to four days the immune memory comes, it is reactivated, and then it stops produces antibodies against the virus again and can catch it again relatively quickly. This then means that there are no serious courses of the disease, but also that such long-term consequences, long Covid, become less likely.

bold: And if I’m one of those people who, for whatever reason, are still afraid of vaccines or generally don’t think the disease is that dangerous and think, well, I can do it without a vaccine, what risk do such people take then a quasi wanting to generate this immunity in such a way?

Wyler: With a dangerous virus like Sars-CoV-2 – and that applies to measles or polio, they are also viruses – it is actually never worthwhile to risk an infection. Of course you can be lucky and not have more than a mild cold without a vaccination, that’s quite possible. But the fact of the matter is that without vaccination, the risk of becoming seriously ill is much higher.

And it is also the case, this vaccination has side effects, the well-known side effects such as lethargy, fever, but also serious side effects can occur. It is still the case, even with this omicron variant, that the risk assessment speaks in favor of vaccination, which means that the risk arising from vaccination is significantly lower than from an unprotected infection.

“Best” time for infection after vaccination: six months

bold: If we now have to build up immunity against Sars-CoV-2 in the long term, does it make a difference if I am in danger of becoming infected, whether that happens shortly or long after the booster? Is there a good or at least better moment?

Wyler: The thing is, immune memory lasts a long time, but of course it gets a little bit worse over the months and years. This means that if you were to look at it theoretically now, it would actually be best if you got infected about six months after the last vaccination. It’s a time when the immune memory is still very strong, but it’s slowly going down, and then you would have an infection like a booster on top.

But of course it’s like that, it’s all a theory, and in a specific case it can turn out quite differently. Ultimately, it’s about what measures do we take, now also individually, to avoid infection? Are we just staying at home now? Do we no longer have any social contacts at all? And I think it’s like this: It’s actually no longer justified given that, as I said, a vaccination protects against a serious course of the disease after a Sars-CoV-2 infection.

Recommendation for previously ill people: another booster vaccination

bold: That is simply the very strong plea that we have to try to reach everyone with the vaccinations as far as possible. The question is: vaccinations don’t work equally well for everyone, you said that at the beginning. There are also people, especially older people, risk groups who are not quite as well protected as others even after a booster. What does it look like then in the case of infection after vaccination? Is it even possible to develop this mucosal immunity if I now belong to a risk group?

Wyler: Yes, it is like that, with older people it has been seen that it takes more vaccinations to achieve the same protection than younger people. And one conclusion from this is that it is definitely highly recommended for, say, over 50 or over 60-year-olds and also those with relevant pre-existing conditions such as high blood pressure or diabetes, especially now with regard to the next one Winter, maybe get another booster shot in September.

And something similar also applies to immunocompromised people, for example people who have multiple sclerosis and then undergo immunosuppressive therapy, where it is the case that you have to look at each individual case to see if the vaccination worked, so to speak. You can then measure the antibodies. And if that is not the case, i.e. if no protection through vaccination is possible because of whatever immune disease, then it is important that these processes can now really be established, that these people can then immediately after being infected with Sars-CoV- Get 2 antivirals.

Increased attention to infectious diseases of all kinds would be beneficial

bold: So there is still a lot of educational work ahead of us and also to reach everyone with this information. Now to conclude: If we look at the public discussion, sometimes people also realize, well, Omicron, even with the boost, it’s probably not that dangerous for me anymore, great, then we’ll be able to let everything run its course now.

Now that we know that it doesn’t work that way for some people, there’s already the moment that we could say: On balance, it might be a bit selfish to say that I’m healthy and fit , that works when you know that other people cannot build up this immunity at all, right?

Wyler: Yes, we have hardly had any problems with infectious diseases in Western Europe in the last few decades, and Sars-CoV-2 has reminded us a bit of what can actually still be lurking for us. It’s not just about viruses, but also bacteria and parasites of all kinds. And I do hope that we’ll be able to do things a little better now, these infectious diseases that aren’t a problem for many people, but for some people that we are which can be better integrated into the healthcare system again in a way that we can say, yes, we have to test a little more, really get a little better under control when these viruses start circulating again. Such increased attention in the healthcare system for infectious diseases of all kinds would certainly be beneficial.

bold: And one hope is still alive, immunity on the mucous membranes via nasal spray vaccination, for which various clinical studies are already underway. The hope that it will still work out next winter is currently rather low. [**]

[*] Here we have made a statement more precise.
[**] At this point we have deleted an assumption that has not yet been verified.

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

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