Influenza, which usually rages in the Northern Hemisphere this time of year, has become virtually invisible.
It’s a small ray of hope in the midst of Covid-19, though the number of people rescued from flu deaths pales next to those dying from the new pandemic. It also poses questions that doctors around the world are likely to grapple with for years to come: If flu can almost be wiped out this season, why not every season? What steps will help prevent the flu from spreading?
“This is an extremely puzzling phenomenon. We are in a historic, incredible situation, ”said Norio Sugaya, a pediatrician who is a member of a World Health Organization flu committee.
The WHO says the measures people and governments are taking to prevent the spread of Covid-19, such as wearing masks and restricting public gatherings, have likely helped control the flu. Increased flu vaccinations can also contribute, it says.
Another hypothesis is that the widespread distribution of SARS-CoV-2, the virus that causes Covid-19, in countries like the US may play a role in blocking the flu by overriding people’s immunity to other viruses. A spring 2020 study in New York City found that people who tested positive for SARS-CoV-2 were much less likely to carry other common viruses such as flu viruses. Yet research into that hypothesis has only just begun.