The Old Continent has once again become the epicenter of the pandemic. Ultimately, alarms the World Health Organization, the virus could kill 700,000 more there, while the territory has already paid a heavy price to the virus since February 2019. The re-containment of the entire Austrian population on the 22nd November sounded like a warning shot: despite the progress of vaccination, we are far from having finished with the Covid-19. Pierre-Yves Boëlle, epidemiologist and modeler (Sorbonne University), deciphers for “Obs” the trajectory of this new wave.
Austria, Germany, the Netherlands … These countries which are (again) tightening the screw in the face of Covid-19
How can you explain this fifth wave which is hitting Europe hard?
It is no wonder that viral circulation is increasing now. When we look at influenza epidemics, we know that historically transmissions take place after All Saints’ Day in temperate countries. The cold season offers good conditions for respiratory viruses such as influenza or Covid. There are several reasons for this: we then live more indoors, which facilitates contamination. The humidity in the air is also lower, so there is less vapor, which creates a more suitable environment for the virus to survive in the air. However, it is difficult to say which factor predominates in this specific case.
Why could the vaccination not be able to counter it more effectively?
Vaccination rates are mixed in the European Union. They are particularly low in countries such as Romania (30.7%), the Czech Republic (58.6%) or Slovakia (42.8%), which explains the strong circulation of the virus in the countries of ballast. More surprisingly, contaminations are also increasing a lot in Germany, Denmark and the Netherlands, where populations are however more vaccinated (respectively 68%, 76.1%, 72.3%). One of the hypotheses is that these countries have been less affected in previous waves, thanks to effective protection measures such as the intensive testing campaign carried out in Germany which then limited the spread of the virus. Natural immunity is therefore weaker there than in other countries such as France or Italy. Add to this the general relaxation of barrier gestures that we observe everywhere and which is due to the weariness of people after months of the pandemic, the reduced use of tests: all these factors put together played a role.
What about immunity conferred by vaccination?
It is known that loss of immunity can be rapid within six months of the last injection. Differences in vaccination schedules have undoubtedly had an effect on the resurgence of the virus in Europe. In Denmark, where the population was vaccinated earlier than in France, we see that circulation started again a month ago. Just like in the Netherlands.
Does this mean that our country will in turn find itself in an untenable situation?
In France, the fact that people aged over 80 are less protected (85.2% of vaccinated) than the group below (96.7% among 75-79 year olds) is very worrying. For this winter, they should be better vaccinated. If what we see elsewhere in Europe is mainly due to the loss of vaccine immunity, it may be that we are struck a little later. But it is impossible to say precisely which factor has the most impact in the current wave. Playing the game of predictions today is even harder than at the start of the epidemic because the factors at play are more numerous. No one can say what will happen in six months.
However, we are well aware of the succession of intense periods of contamination. Did this new wave surprise you?
What is certain is that we would have preferred the vaccination to be more effective in countering infections. Messenger RNA vaccines are miraculous, they provide very good protection against severe forms, but it seems to sag faster against transmission. One would have thought that the pressure on health systems would have eased more quickly. In September, however, I was optimistic, I thought we would have a more or less normal winter. This is not the case, but I continue to think that we will be able to manage this epidemic like the flu. Before the epidemic, there were already problems with beds in hospitals every winter because of the flu. Everyone seems to discover that you can be hospitalized and die from infectious diseases!
Even if it is so far very difficult to make predictions, what scenario can we expect in the longer term?
The least reasonable scenario is to think that the virus will go away like this. The Covid-19 will still be circulating in ten years. I think we’re heading for an epidemic « grippe-like » (similar to influenza), or a seasonal epidemic. If we do longer-term fiction, we can imagine that after four or five episodes, we no longer have severe cases because a natural immunity will have been formed. We can see that the Covid does not do much among young people. If over the next few years children and young people continue to become infected, they will no doubt have established reasonable immunity. For older people and those at risk, a repeated vaccination strategy should be applied.
Anti-Covid vaccine: towards a third dose for all?
The problem is that when a very large number of people are affected, even a small flu can kill a lot and put a strain on the hospital system. The Covid is like a hundred-year flood and our health system is not sized to cope with such an event. We can still think that mortality will eventually decrease. In human history, no virus has ever wiped out an entire population. I don’t see why it would be any different. The coronavirus will be just one more virus, hoping it doesn’t have an “additive effect” to that of the flu, but that the two viruses will compete with each other. However, many questions remain unanswered. In particular, what will be the mortality of the Covid in the long term? Will it have the same fate as the other “humanized” coronaviruses, which today only give rise to a cold?
“As long as North-South inequalities persist, the Covid virus will continue to kill and mutate”
Another fear remains, the existence of variants. Should we fear the imminent appearance of a new variant?
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There will undoubtedly be new variants, but it is not known whether they will be selected. Let us recall that between the Alpha variant which succeeded the historic strain and the Delta variant which is rife today, other variants have appeared without necessarily having much effect. What we do know is that a virus has an interest in increasing its transmissibility in order to last, but not its mortality.