What does a winter virus like in a summer like this do: many respiratory diseases that disappeared during 2020 begin to appear at unexpected dates
Respiratory viruses are back. Pediatricians have been warning it for weeks and now the data is beginning to show it in all its glory. As Jessica Mouzo pointed out today in El País, according to the latest epidemiological surveillance reports from the Carlos III Institute, positivity for respiratory syncytial virus (main cause of childhood bronchiolitis) went from 2% to 4% in one week.
It is not an isolated data, according to Fernando Baquero, coordinator of pediatric infectious diseases at the Hospital de La Paz in Madrid, “RSV infection has also skyrocketed in the USA in recent weeks“. If we look at the updated data, the virus epidemic seems to be starting to collapse these days, but the trend is undeniable. In Australia too something similar happened at the arrival of the austral summer.
The most obvious debate is whether, behind this revival of respiratory viruses that have been missing during the pandemic, is the relaxation of sanitary measures and a society that (half due to pandemic fatigue, half due to a calmer epidemiological situation) has raised its foot Of the accelerator. The truth is that (although discussing this now, without more data than what is available, it has little practical use) there are interesting things to keep track of.
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An out-of-season virus
What is happening with VRS? However, there is a more interesting question: “What is a winter virus doing roaming around in the middle of June?” It should not be forgotten that the epidemiological surveillance records are very clear: RSV usually appears in September and October and reaches its peak in December. Why are we meeting him at the gates of summer? And, beyond that, are we facing a more significant change in viral dynamics?
Competition between viruses Without ruling out, of course, the effect of the relaxation of sanitary measures (something that, in addition, would invite us to take with some polls published these days on the use of the mask after the ban), the truth is that there must also be some “interference” between viruses. If the peak of RSV occurs in December it is because, “as soon as the flu appears, it disappears.”
In the end, all these respiratory viruses (of which the VRS is only a sample) circulate ‘silently’ through society until the conditions to “explode” are met. Those circumstances, by surprise, have occurred these weeks.
A temporary or long-term change? What is pending now is what happens with the coronavirus in the medium term. If it turns out to be just another respiratory virus, seasonal dynamics should return to their “traditional” place; In contrast, if SARS-CoV-2 remains an important seasonal virus, the rest of the diseases will have to move to find their windows of opportunity.
Picture | Kelly Sikkema