Endemic pediatric viruses are back. Those common pathogens of children are back among us after they silently left the scene due to an indirect, side effect, of the preventive measures against Covid. In fact, without there being the intention, due to masks and lockdowns and social distances and closed schools, together with Sars-cov-2 also the respiratory syncytial virus (vrs), the enterovirus, the flu virus, the rhinoviruses , have stopped circulating. To reappear, once the coronavirus containment measures are relaxed.
They strike at different ages and with different seasonality
But they reappeared with a different seasonality, involving children of different ages and also with effects of different severity. In a word with a new epidemiology. We must prepare for all this. And it’s not necessarily easy, because the future is ultimately uncertain. The article published in the Lancet clearly speaks of uncertainty.
A change of scheme
The Authors – University of Colorado Infectious Disease Pediatricians and Princeton Ecology and Evolutionary Biology Experts Coordinated by the Pediatrician Kevin Messacar – report that before 2020 the respiratory syncytial virus (vrs) and influenza viruses reached their peak in winter and in temperate climates, enteroviruses circulated from summer to autumn following known cyclical patterns. But the Covid pandemic prevented the circulation of these pathogens, which then reappeared following unexpected patterns. There was no seasonal enterovirus activity in 2020, but enterovirus D68 resurfaced in the fall of 2021 in Europe.
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In 2020, we still read about Lancet, which reports a reflection more relative to the United States but certainly reproducible elsewhere, there has not been the typical winter wave of hospitalizations due to the syncytial virus (the pathogen responsible for bronchiolitis). But when the masks fell off, the vrs epidemics resumed the following spring, however, affecting older children. The flu virus had the same pattern change, which did not manifest itself in winter but did so a few months later.
Prepare for uncertainty
In short, after 2020, pediatric infections have begun to change. Now: is it possible to predict how the epidemiology of these pathogens is changing? Or, more precisely, what can we expect in the near future? Messacar contacted a group of epidemiological modelers from Princeton University’s Department of Ecology and Evolutionary Biology – Rachel E. Baker, Bryan Grenfell, Sang Woo Park who signed the publication with him on Lancet– and asked them to come up with a forecast.
Epidemiological models no longer work
But the answer “was that we must prepare for uncertainty”, as Messacar himself declared. In practice, the pediatrician said, we must take note that the epidemiological models we relied on in the past seem to no longer work in recent years, close to the pandemic. And act accordingly: that is, keeping attention a little higher, recognizing suspicious cases, in a word being more alert. Doctors – according to pediatricians who signed the article on Lancet – must know and be familiar with the pathogens circulating in their area, keep in contact with local epidemiology services and use data here to make clinical practice decisions.
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In Italy
Fabio Medulli full professor of Pediatrics, director of the maternal and child department of Sapienza University of Rome and head of the pediatric emergency room of the Umberto I polyclinic, reminds us that the article on Lancet reports what even the Italian experts have “recorded and documented”. In fact, Midulla and other Italian colleagues have published three studies on this same theme. One, released in July 2021 in the pages of Pediatric Pulmonology, wondered, expressly in the title, where the syncytial virus had gone during a pandemic.
A second research, published in Frontiers in Pediatrics in July of this year, was once again on the syncytial virus. And a third study from March 2022 on Acta Pediatrica instead examined several respiratory viruses ‘disappeared’ from pediatric hospitals during the pandemic.
What’s going on?
But what happened, what is happening and if and what can we do to avoid indirect Covid damage to children due to viruses other than Covid? “It happened that the primary prevention measures that limited the spread of Sars-cov-2 changed the epidemiological trend of the respiratory viruses that normally circulate in the pediatric population: syncytial virus, influenza, rhinoviruses, enterovirus , which are responsible for bronchiolitis (especially the syncytial virus), pneumonia, preschool asthma – says the expert -. Now the problem is that the slowdown of coronavirus prevention measures, with cold, humid, the rains and the reopening of schools could make these viruses circulate more intensely and with more important clinical manifestations “.
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No antibodies from mothers to babies
During the period of closures and social distancing, pregnant mothers did not come into contact with the most common viruses, which prevented them from making antibodies against many viruses, and in particular against respiratory ones, and transmitting them to newborns. “A phenomenon that could mean that when the virus, for example syncytial, begins to circulate, those children born without maternal antibody protection fall ill with more serious forms of the disease”, explains Midulla.
Then there are the older children, those who were born during the primary covid prevention period. They too have not been in contact with viruses because they are more isolated at home, “of course, and these children risk contracting infections when they are older – continues the pediatrician -. Lancet in fact, they highlight two peaks of infection in the 2020-2022 period close to the closures: the children most at risk are the children born later and precisely those born during “says the pediatrician.
The importance of health education
The primary prevention of Covid has also changed the seasonality of the viral epidemiology, “Before the pandemic, the respiratory virus season was December-March, but in 2020 and 2021 – Midulla continues – it was September-December. All this requires a ‘particular attention: health facilities must be ready to recognize cases and any epidemics, and to welcome children and pediatricians in the area to do a good health education “, telling parents not to send children back to school unless they are perfectly healed, to prevent children from being in very crowded places and where people smoke, and to encourage breastfeeding.
A year and then (maybe) enough
But how long will we have to deal with this Covid-modified epidemiology? “I think that probably still for this year, and then that’s it. When there is no longer a need for preventive measures against Covid – predicts the expert – the rest will return as before”.