[ad_1]
The US is not the only place experiencing a rise in off-season RSV. Australia, South Africa, Iceland and several European countries also did it. In France, the RSV arrived four months late — instead of April-December — according to Jean-Sébastien Casalegno, a physician and virologist at the Institut des Agents Infectieux in Lyon’s Hospices Civils and a leading author. March prepress describing the occurrence.
There are not many models to indicate what can happen next. Will RSV return this year and have a shorter and weaker season in its normal time frame? Will it rotate around the calendar until it slowly returns to its proper place? “The season is likely to return after several seasons,” Casalegno says. “It’s all complex next season, what’s going to happen.”
Viruses are seasonal for complicated reasons, not because they have evolutionary preferences for certain temperatures and humidity, but because winters are often the time when people gather indoors. There are also seasons, as it takes a short time to create a large number of vulnerable people — those who have not been vaccinated before or who have been vaccinated — to have enough territory for the virus to reproduce and survive. to new hosts.
How this “sensitive” group spreads is different for each virus. For RSVs who cycle every year, the youngest children are most at risk. At school age, most children have gained immunity from infections or from exposures that do not cause symptoms but that repeatedly allow their immune systems to create defenses.
The EV-D68 is also seasonal, but in a more complicated way. First, appearances occur in the summer, not in the winter. Second, as demonstrated in the first analysis of its seasonality, published in March Science in Translational Medicine, which seems to cause both respiratory illness and floppy disk paralysis every two years. According to this analysis, the cycles are affected by climatic conditions, but also by the immune system: women who suffer from EV-D68 while pregnant are given antibodies against it to their babies. Thus, in the first 6 months, babies are protected against the disease and weakened to the extent that passive immunity is diminished. This later weakness, combined with seasonality, seems to encourage a slower accumulation of sensitivities.
The final appearance of the EV-D68 was expected to take place last summer, in 2020. As with RSV and the flu, it didn’t arrive, and for similar reasons: Masking, walking distances, washing hands, and protecting children at home. vulnerable then. And as with RSV, no one knows for sure what will happen.
“They don’t love enteroviruses for a few years, they’re out of luck,” says Kevin Messacar, an associate professor of pediatrics at the University of Colorado and the University of Colorado Hospital who collaborated on that March study. “The model of this whole family of viruses, which is well described, would not predict that we would have to wait until 2022 because we have lost a cycle of an outbreak. It would say that we are constantly growing the set of susceptible people who have not seen this virus.”
A participating national project says EV-D68 is finding its antibody levels lower than usual in pregnant women because they have not been exposed to the virus in the past year and therefore cannot be protected. This means that each time the EV-D68 is repeated, other children may become infected or get sicker than the virus, or take it earlier in their lives, in the most vulnerable months of childhood, when they would otherwise be protected.
There is the flu, which is always unpredictable among respiratory infections because it is constantly changing to prevent our immune defenses, exchanging the prevailing strains for new ones and sometimes causing mild illnesses and sometimes destructive ones. The flu is, right now, the infection that causes the most anxiety in the future. Without making a dramatic return to social distance, “I expect a terrible flu season,” says immunologist Sarah Cobey and associate professor of ecology and evolution at the University of Chicago. “I hope more people get the flu. I also hope to have a very bad flu infection. “
[ad_2]
Source link
