As autumn fades until the winter of last year, some researchers of infectious diseases began to draw their attention from the Covid-19 pandemic and returned to something more familiar. It was the time of year that they usually started looking at their numbers for flu, the seasonal flu – to see how bad the outbreak would be, and to determine how well the vaccine of the year handles the protea respiratory virus .
The answer was: bupkis. Almost no one was sick or died of flu. A year earlier, during the 2019-20 flu season – basically autumn and winter, with a peak in December, January and February – 18 million people in the US saw a doctor for their symptoms, and 400,000 had to be hospitalized be recorded. In total, 32,000 people died. But in the current season, business has barely crossed four figures. ‘There’s always a vaccination and flu season. We’re used to working in the pattern, and the pattern has disappeared, ‘says Emily Martin, an epidemiologist at the University of Michigan School of Public Health who is part of the Centers for Disease Control and Prevention’s influenza monitoring network. ‘Now, I’m glad I didn’ t have to do Covid control and flu control at the same time. It would have been a disaster. But at the same time, it’s this strange year. ”
Indeed strange. And it’s not just flu. Cases for respiratory synthesis virus, which mainly affects babies and, like flu, also has a seasonal rhythm, is the bottom line. According to an article released last week, the missing list also contains enterovirus D68, a likely culprit behind the polio-like childhood disease acute flaccid myelitis. The virus and AFM come about every two years in the cycle, and the last round in North America was in 2018. In 2020, they also did not miss their answer.
The why of which is not really a mystery. Probably. Most likely, all the masking, physical distance, hand washing and other ‘non-pharmaceutical interventions’ that anyone can do – OK, almost all – did to prevent the spread of Covid-19, the kibosh also put on those other viruses. This is not the only hypothesis, but it is a good one.
The mystery is the how and the what-next. The answers can teach scientists more about how other diseases infect people and how to stop them. The mechanics of why these NPIs crushed at least three other respiratory viruses while Covid-19 became unbridled are not clear. And even less clear is what a year without flu will mean for the next winter and for the winters thereafter. Influenza kills 12,000 to 61,000 people annually in the US and costs the economy $ 11 billion annually, according to one estimate. For decades, even centuries, people have accepted the risk. But if it turns out to be almost completely preventable, will people’s willingness to tolerate the risk change as well?
Pandemics happen when a virus hits its evolutionary groove. The virus that causes Covid-19 is called SARS-CoV-2, and when it went down in late 2019, no human immune system has seen it before. No one had any defense. The fact that people who have no symptoms could transmit it made it different from most of its cousins with respiratory pathogen – just different enough to take advantage of social interactions between people and go worldwide.
But just as it only takes the slightest circumstance or genetic twist to make a virus into a pandemic, the disease version of an arena filler, it is also not very necessary to limit a disease to the equivalent of playing of small clubs. “The Covid-19 controls – mask wear and social distance – really work, and they work very well for other respiratory pathogens,” said Rachel Baker, an epidemiologist at Princeton University. The main difference is probably that these other diseases have been playing out for thousands of years, and that humans are a bit in their fascination. Even flu, with its well-known variable genome requiring a new vaccine every year, leaves some immunity on the population. “With the seasonal diseases, we have a lot of population immunity, we have vaccines, and most people older than 2 years have RSV,” Baker says. “That’s why you do not have a seasonal pandemic.”