As Covid-19 continues to surge in the US, with a record number of more than 4,000 virus deaths on Friday, some good news has come from data about the flu.
During a typical flu season, the number of people getting the flu would just be starting to rise, with the peak typically coming in February. Yet so far, only 0.2% of 400,000 swabs for the flu have been positive, according to data from the Centers for Disease Control and Prevention. During the same time last year, the positivity rate was 13%.
With hospitals across the country near or at capacity with Covid-19 patients – about 132,000 people are currently hospitalized with Covid – flu’s minimal presence is a blessing. At least 38 million Americans had the virus during the 2019-20 season. While the flu is less deadly than Covid-19, it has the potential to strain the healthcare system during a bad year. Last year, 400,000 people were hospitalized with the flu and 22,000 died from it.
“Covid is causing an incredible stress on the healthcare system in many parts of the country,” said Dr William Schaffner, a professor of preventive medicine and infectious diseases at Vanderbilt University. “Even if we had a mild to average [flu] season, we would all be swamped at the moment.”
Instead, “we’re having, to date, a profoundly mild influenza season,” Schaffner said.
Multiple factors have played a role in dampening the flu this season.
The virus usually makes its way to the northern hemisphere after spreading in the southern hemisphere, which experiences its flu season from June to August. But the 2020 flu season in the south was virtually non-existent.
Public health experts believed that measures in the southern hemisphere to prevent the spread of Covid-19 also worked to stop the spread of the flu. Though the flu is also a respiratory virus, it is not as transmissible as Covid-19, so mask-wearing and social distancing are more effective at disrupting flu spread than the spread of Covid-19. The low number of cases, paired with the decrease in travel between the northern and southern hemisphere, boded well for the flu season in the north.
Still, Americans were urged to get the flu vaccine to decrease the chances of a feared “twindemic” of flu and Covid-19. More than 192m doses of the flu vaccine were distributed throughout the US by the end of December, according to the CDC, the highest number of doses distributed in a single flu season.
It appears the bulk of those doses have been used. More adults in the US got the vaccine this season compared with years past, according to the CDC. About 53% of adults have received the flu vaccines. Around the same time last year, 42% of adults had been vaccinated while 48% were vaccinated by the end of the last flu season.
Schaffner said schools undertaking measures to prevent the spread of Covid-19 – extensive cleaning, masks and social distancing and holding classes virtually – probably also played a key role in stopping the flu’s spread. Children shed the flu virus more than adults do and for longer periods of time, making it easy to spread to family members and teachers who can spread it to other adults.
“Children have been much more isolated, so this distribution mechanism has been effectively shut down,” he said.
While there is much to celebrate about the low flu numbers, the US is not out of the woods yet: there is still a chance the virus could see a surge, especially since millions of Americans traveled over the holidays.
But Schaffner said there was cautious optimism that the US had avoided the worst of a “twindemic”.
“We continue to be very alert to that possibility, but so far, I think we’re on a record-setting pace for a low flu season.”