Many who have recently had Corona console themselves: As they have recovered, they are now through with the virus. Is that correct? We asked the President of the German Society for Immunology, Christine Falk.

FOCUS Online: “Through Corona”, at least until autumn – does that apply if you recently had Omikron?

Christine Falk: Unfortunately, you can’t say that in general terms. The different variants protect sometimes more, sometimes less well against other variants. Especially with Omikron, the “less” was particularly noticeable recently…

Falk: Personally, I don’t think the term was chosen particularly well. It falls short because “escape” is only partially applicable. The fact is: Immune protection is something that varies greatly from person to person. If I am vaccinated, ideally three times, I usually have good protection against a severe course.

Antibodies against the spike protein can be detected in the blood immediately after the vaccination and also in the weeks and months that follow. In addition, specific T-cells with a long-lasting memory. This doesn’t take effect quite as quickly, so it doesn’t necessarily protect me from infection, but it does reliably protect me from severe courses. As already mentioned, there can be no talk of escaping the entire immune cascade! What is true, however, is that even vaccinated people are not necessarily immune to an infection of the nasopharynx with Omikron. This is where this virus actually has an advantage compared to other variants.

Can you explain this advantage in a bit more detail?

Falk: I like to imagine an old key that you use to open a lock. The key is the virus, the lock is the receptor on the cell. Now Omikron has changed precisely at the point where the bit of the key fits into the lock and the cells in the nasopharynx are more or less unlocked. The aim of the vaccination was to cover the beard with antibodies like chewing gum in such a way that the lock and key principle no longer works and the virus can no longer infect the cells.

This state is called sterile immunity: Not only do we not get sick from the virus, we don’t even become infected. Let’s imagine the situation with the omicron like this: Because the beard of the key has changed slightly, the antibodies against the beard region no longer fit and the virus can still open the cell lock with its special key. Therefore, Omikron can partially undermine the immune response after vaccination.

When you talk about the nose and throat: is it about the so-called mucosal immunity?

Falk: Yes, exactly. The nasopharynx is still the entry point for this virus and the degree of mucosal immunity varies greatly between individuals. Incidentally, that is exactly the reason why people are currently in the process of launching the vaccination as a nasal or throat spray. The hope is that the immunity of the nasopharynx will then be greater and longer lasting.

If I’ve been vaccinated and then had Omikron: Doesn’t the infection then act a bit like another booster and thus like an extra good protection against further infections?

Falk: That’s certainly the case to a certain extent, but unfortunately you can’t absolutely rely on it. In principle, this is similar to the earlier breakthrough infections: You get infected with omicron, despite multiple vaccinations. After an infection after vaccination, there is also immunity against the other virus proteins. It is therefore actually unlikely that you will be infected twice with exactly the same variant.

However, two consecutive infections with omicron subvariants are quite conceivable. For example, once you have completed your B.A. 1 and once with B.A. 2 is infected. As a rule, after an infection with omicron, the body also seems to be able to recognize earlier variants such as delta. Conversely, if you had Delta, that doesn’t necessarily apply to Omicron, as explained above.

That sounds a bit like the lottery: which variant do I have and when?

Falk: Let me put it this way: The question is not so much whether the virus gets into the body. The question is rather: can it spread further afterwards or is this prevented by the so-called systemic immunity in the blood? Currently we are mainly busy with B.A. 5, a variant that is currently occurring frequently in Portugal.

For all we know, B.A. 5 evolves independently of B.A.1 and B.A.2 – within the omicron variant. At this point in time, we cannot say exactly how well we are protected from B.A.5. What we should emphasize, however, is that it is always best to get vaccinated first and then possibly become infected. Please in this order – not the other way around.

But don’t I go into the autumn with good protection even if I’ve been infected with Omikron at some point in the last few weeks without having been vaccinated beforehand?

Falk: In fact, you are probably in a little better shape than without any infection or vaccination. However, we know that immunity after a single infection lasts less than immunity after triple vaccination.

And that despite still being vaccinated with the same vaccine as a year and a half ago? Say: Against another variant?

Falk: Vaccination is against the wild-type sequence of the spike protein. The spike protein consists of 1273 amino acids, which can be imagined as being threaded on a string of pearls. Let’s not forget: Only 30 to 40 of these pearls have changed in the omicron subvariants. The others are still identical to the Wuhan sequence, so to speak.

In other words, even if the virus continues to mutate: it will essentially remain similar to the original variant?

Falk: Based on the experience of the last two and a half years, it can be assumed that this is the case, and that is precisely why the vaccination remains so important. Going into a rampant wave not vaccinated is like taking a penalty without a goalkeeper.

The ball is the virus, the immune response is the goal?

Falk: Exactly. Or, if you want to be more differentiated: If you are vaccinated and have a lot of antibodies, you have a defensive wall like with a free kick. The first front is then, so to speak, the IgA antibodies in the nasopharynx, which stick together the bit of the key. They prevent the virus from even getting near the gate. Further back, in the gate itself, the T-cells provide protection because they can recognize and kill infected cells. Antibodies or not: A good goalkeeper will still flatten the virus after infection.

And a not so good one?

Falk: Well, if I have a pre-existing condition or if I’m over 70, there may be gaps in the defensive wall. In such a case, the opposing team, i.e. the virus, can score a point despite the defensive line. And if the body is also without vaccination, that is even more true. Unfortunately, we cannot reliably predict whether the individual defense has Champions League qualities or whether it is more of a district league. By the way, that helped me a lot when I recently got infected. I knew that the virus wouldn’t get very far because the systemic defenses are in the blood. And that’s exactly how it was. I only had mild symptoms.

Are you afraid of getting infected again after the summer?

Falk: Fear is definitely the wrong word. But I’m not fooling myself: Of course it can get me again because the mucosal immunity doesn’t last as long as the systemic one in the blood. We should definitely remain vigilant. The situation is different from last year.

What are you alluding to? The corona numbers are falling.

Falk: That’s true, but much slower than in 2021! We’re starting the warm season comparatively poorly, and anyone who expected the light-heartedness of last year is likely to be disappointed.

So don’t be scared, but…?

Falk: Thanks to the three vaccinations and the infection, I feel well prepared. What my body has been going through recently was a kind of stress test. I think many who have had Omikron feel the same way: you understand your own body reactions a little better when you know that the immune system has a head start.

In what way?

Falk: What I noticed about myself was not the virus that had spread through my body. But more the vaccination, which has shown an effect and prevented the virus from spreading into the lungs.

And now you are in a better position than someone who has “only” been vaccinated and has so far been spared by Omikron?

Falk: Caution, an infection should be avoided in any case. Long-Covid is becoming rarer through vaccination, but cannot be completely ruled out. Means: This danger exists again with every new infection. How tall is it exactly? We cannot say that at this point in time. In any case, I say for myself: on the train or when many people meet, I will continue to wear a mask. Also in some interiors. I just don’t want this virus!