Covid-19, bronchiolitis and influenza: the triple epidemic that threatens this winter

It is an unprecedented winter. Influenza virus, rhinovirus and respiratory syncytial virus (RSV), responsible for most cases of bronchiolitis… For the first time since the start of the Covid-19 pandemic in France in March 2020, several other respiratory viruses are circulating at the same time. SARS-CoV-2, at very high levels. The lifting of restrictive measures, such as incarceration or mandatory wearing of masks, usually allows seasonal viruses to spread.

Beyond the Atlantic Ocean, this intense co-circulation has become a popular term “triple”A triple epidemic that threatens – even in the United States – a healthcare system already greatly weakened by the pandemic and the structural hospital crisis. “This year’s special challenge is to study the interaction of SARS-CoV-2 with other viruses.Emphasizes Anne-Claude Cremieux, a professor of infectious diseases at the Saint-Louis Hospital in Paris and the author of the book. Citizens have a right to know (Fayard, 324 pages, 20 euros).

The bronchiolitis epidemic, which especially affects children under 2 years of age, began in early October, while it usually follows a very regular cycle, starting in mid-November, peaking in December and ending in January. After a dip due to the school holidays, emergency department visits and hospitalizations rebounded from the week of November 14 to levels not seen in a decade. At the origin of this infection of the bronchioles, RSV and rhinovirus share a metropolitan area, one or the other manifesting itself differently depending on the region.

It’s also an early start for influenza, which is known to have greater variability in the onset and extent of its seasonal outbreaks. After Brittany, four other regions entered the pre-epidemic phase, according to the November 23 Public Health France (SPF) bulletin. Currently, the dominant subtype is the A(H3N2) virus. “Whoever says H3N2 is saying a pretty strong epidemic that mostly affects people at risk.”Emphasizes Vincent Enuff, deputy head of the National Reference Center for Respiratory Infections Viruses at the Pasteur Institute. Each year, flu epidemics cause 8,000 to 10,000 deaths, a threat if most strains remain as H3N2 flu. » This virus is not necessarily more dangerous than others, but it is genetically evolving a lot, making it difficult to acquire long-term immune protection.