Swiss infectious disease specialist: ‘Our immune system needs an update’

It feels like everyone is sick right now. Is that correct? And are there more diseases than before the pandemic?
Jan Fehr: Yes, the impression is correct. This is also apparent from national and international figures. Yesterday I just saw the latest data for North America and Europe. It is very impressive to see how many more people are sick compared to the winter before the pandemic.

Any why is this the case?
As always, it’s probably multiple factors. It is crucial that we properly protect ourselves during the pandemic with distance, hygiene and masks. This has also stopped other respiratory viruses – not just Covid-19. Hardly anyone got the flu then.

But now these rules of conduct are being ignored again.
Right. We again tend to go to the bar or to the office despite the cold. And if you look around on public transport, very few people wear a mask there – even if they stand shoulder to shoulder and cough or sneeze. We protect ourselves less.

Are we also more vulnerable?
During the pandemic, our immune system – apart from Covid-19 – has had only limited contact with respiratory viruses. That is, the immunological memory could not be updated. Actually, it’s just like updating a computer.

Is there already a flu epidemic?
As the numbers now show, this could be the start of a flu epidemic. And if so, it would be significantly earlier than before the pandemic.

Which is better: wearing a face mask or exposing yourself to the virus and hardening yourself?
This “resting” and “hardening” is not a good idea. It may be playing with fire and only works to a limited extent as we imagine. Most guys manage just fine when they get sick. But there are always people who cannot or cannot protect themselves properly because they are old or sick and have a weakened immune system. You should always keep it in mind. And don’t forget: it can also hit you hard. Again and again, young people end up in intensive care. These are rare isolated cases, but as an individual you still don’t know if and how it will affect you.

So whether it’s Covid-19 or not, a mask is generally a good idea?
A mask in winter makes sense when many people are together in a small space. However, I am not in favor of a general obligation to wear masks – always and everywhere. We need to find our way back to a normalization of social life. This is important for our psyche. I am an infectious disease specialist, but the chair I hold at the University of Zurich is also responsible for public health – and that includes mental health.

You mentioned “update”. Do you have to be sick regularly to be particularly healthy?
The distinction between being healthy and sick is not always clear. It’s not just sick or not sick. You can also become infected, but not or only slightly ill. This is the ideal case: the immune system is so up-to-date that it immediately knows which pathogens it is dealing with and how to efficiently fight the invader.

Has the immune system been shut down during the pandemic?
no The immune system fights countless pathogens every day. However, there are certain pathogens, especially respiratory ones, that have become rare in recent years, so that our immune system is no longer so well prepared for them. It is therefore not out of practice, but can simply respond less quickly to the pathogens mentioned.

Which viruses are currently circulating?
The data from the BAG records flu-like illnesses – a collection jar that also contains Covid-19. Looking at the steeply rising curve, you can’t unravel what’s what – not to mention the number of unreported cases. But further data shows that flu viruses are currently circulating heavily. The RSV virus is also very prominent – and has brought children’s hospitals to the attack in recent weeks.

And the rhinovirus, so a cold, is there too?
Yes, but not as prominently. At least in the situations where tests have been made. Again, the number of unreported cases is likely to be high. What is interesting about the BAG report is which age group is most affected.

Which?
The 15 to 29 year olds. They are on the road the most: going out, at school, in clubs, on public transport. This shows how mobility, and that is all well and good, affects the spread of viruses. A factor that was also crucial during the pandemic.

The RSV virus is especially critical for children. Many had to go to the hospital with bronchitis. Are the kids now catching up on all the infections they were spared during the pandemic?
The small children born in 2020 or 2021 are still “naïve” when it comes to infectious diseases. They are only now really coming into contact with viruses. It’s like learning to walk: you can’t go straight to the sprint, you have to get up, walk, fall. The same goes for their immune system, which has to learn how to deal with these viruses and build up protection against them.

The data from the BAG also shows that flu-like illnesses are increasing earlier than in other years. How will the curve develop?
You can’t predict that. Most of the time though, things will normalize at some point. You can also assume this time. All that can be said about the curve is that it is rising earlier this year and rising more steeply than in the years before the pandemic. What matters is what the coming winter weeks will look like. We must prepare for all scenarios, including a further increase in flu-like illnesses. It would be all the more important that the government continues to pay for the covid-19 tests in the new year. So that we are not in the dark, at least for Corona.