With this statement, the experts refer, not to a decrease in the number of cases, but to the fact that the cases of the currently active outbreaks would be milder than those registered in the most intense moments of the pandemic.
An example of these opinions is Juan Abarca, director of the HM hospital network, who stated on May 19: “ What happens to the virus? The reality is that it has been attenuated, either by the effect of ultraviolet radiation or by the existence of more benign mutated strains. That, which goes beyond the effect achieved by the confinement and other public health measures, means that the end of the health crisis, fortunately, is approaching faster than expected ”.
At the moment, these opinions are based on anecdotal evidence. Our working group has tried to confirm or refute the weakening hypothesis with the statistics published up to the end of June: the low quality of the available data tentatively points to weakening but, unfortunately, does not present conclusive evidence.
The apparent weakening of COVID-19 could be due to any of the following reasons (or a combination of several of them):
The virus itself could be attenuated
Milder strains could appear and take over. At the moment, we know that SARS-CoV-2 is relatively stable, at least much more so than other viruses such as influenza, due to its efficient mutation control mechanism.
However, this does not mean that there are no mutations. A mutation has already been identified that makes the virus more contagious. On the other hand, a few weeks ago it was announced that a milder strain had been isolated in Brescia (Italy). Furthermore, we must remember that both SARS and MERS underwent mutations that made them less aggressive. It is key to continue doing sequencing studies that can confirm what evolution the virus is undergoing. However, attenuation of the virus is not the only possible cause.
Environmental conditions change
Environmental conditions are changing and these conditions have an impact on disease. Much has been made of the possible impact of dependence on UV radiation or temperature, claims not supported by evidence, but rather in parallels drawn from the behavior of other coronaviruses.
The sick change
Those first affected by the epidemic tend to be the weakest (in this case, the elderly). Once the weakest part of the population has been affected, the epidemic may appear to weaken only because the remaining population is stronger.
On the other hand, the most fragile tend to maintain better social distancing and follow the recommendations with greater diligence. If we had data on the demographics of the latest outbreaks, we could study whether these are disproportionately affecting young people or whether outbreaks in residences, hospitals or nursing homes are still significant. It is reasonable to think that this is a key factor in the severity of the flare-ups we are experiencing.
We better understand the disease
A better understanding of the disease and better treatments would mean that fewer cases progress to the critical stages of the disease. For example, we know that in the early stages of the epidemic, many cases did not receive hospital care until the disease had already progressed to a critical stage.
Distancing reduces the severity of cases
Finally, distancing measures could reduce not only the number of infections but also their severity. This would be the case if the intensity of symptoms is dependent on viral load and viral load is limited by social distancing.
A possible weakening of symptoms does not change the fact that we must continue to maintain social distancing and that masks or hand hygiene have become a key part of our routines. Research is necessary to clarify the possible weakening, but the publication of data related to the severity of the cases emerging in the epidemic is even more urgent: we not only need updated and localized data on cases and deaths, but also on hospitalizations. or admission to intensive care areas. Only then can we clearly determine our next step in the fight against the pandemic.
Sara Lumbreras, professor and researcher at the Institute of Technological Research, Universidad Pontificia Comillas; Joaquín Fernnández-Crehuet Navajas,, University of Malaga and Lluis Oviedo Torro, Full Professor, Pontificia Università Antonianum
This article was originally published on The Conversation. Read the original.
