While the country suffered from a devastating wave of coronavirus cases in the winter, phones from Old Dominion Pediatrics in Virginia rang non-stop. People who called with infected relatives sought advice on ways to put the quarantine at home so that other people would not get sick.
But no one asked about the flu.
And the test results that Eric Freeman was seeing showed that dozens of his patients had the coronavirus, but almost none had tested positive for influenza.
“COVID just turned out to be the dominant viral pathogen at the time and really did not allow the flu to have enough space to populate properly,” Freeman said in an interview on Monday. “I haven’t had a rapid flu test positive in my office since before Thanksgiving.”
Public health experts, general practitioners and pediatricians have warned for months that an increase in coronavirus cases during the winter months would be exacerbated by a typical flu season, which kills tens of thousands of Americans annually. But a funny thing happened in the midst of a global health pandemic: the flu season was effectively canceled.
Data from the Centers for Disease Control and Prevention (CDC) show that only 1,893 Americans tested positive for the flu virus this year, among the results of clinical laboratories and public health. By that time, in the past year, more than 290,000 people had tested positive for influenza.
The CDC reported in August that 198 children died of influenza-related causes during the last flu season, a record. So far this year, only one child has died, the lowest count since records began to be kept in 2004.
“You would never think that there would be a silver lining for this [pandemic], but this is as close to a silver lining as ever, ”said Peter Hotez, a pediatrician and dean of the National School of Tropical Medicine at Baylor College. “This is what wearing masks and social distance and has probably reduced face-to-face classes [does]. ”
Less than 1 in 1,000 hospitalizations this year were for influenza, a seventh of the proportion recorded in the last low-flu season in 2011-2012.
American health officials and vaccinologists usually gather important tips about the coming flu season from the viruses that begin to circulate in the winter months in the southern hemisphere, our summer months.
But even as these officials sounded the alarm about the potential for a double season of respiratory illnesses, the governments of Australia, Chile and South Africa reported sub-normal circulation of flu. Viral curves in these three countries started to decrease much faster than in previous seasons, as new blocks and restrictions were put in place.
“In the past twelve months, with the exception of some West African countries and some Southeast Asian countries, no one has had a flu season. And that in countries that closed really strictly, it is in countries that may not have closed so strictly. It confuses me a little, “said Richard Webby, director of the World Health Organization (WHO) Collaborating Center for Studies on Influenza Ecology in Animals and Birds at St. Jude Children’s Research Hospital.
The same thing seems to be happening in the United States. The flu is less transmissible than the SARS-CoV-2 virus, which causes COVID-19, which means that masks and social distance are likely to have an even greater impact on the total number of flu cases than on the coronavirus. Closing schools meant reducing one of the most prolific vectors of person-to-person transmission.
“Young children and schools are important players when it comes to communicating flu in the community,” said Webby. “With many schools not open or control measures actually being carried out in schools, this has had a major impact on flu outbreaks.”
And, Freeman said, parents took warnings from public health officials seriously that their children should get the flu shot. Although the final data on flu vaccine acceptance rates have not been known for months, Freeman said the vaccine acceptance rates in his practice, south of Richmond, Virginia, were substantially higher than in previous years.
“This was one of the best years I have had in 15 years of flu vaccination. This year, the parents were definitely engaged, very excited, ”said Freeman. “It got to the point where I couldn’t keep flu shots on my shelves.”
Apparently, nothing about the coronavirus pandemic was easy, and some experts have warned that even the least damaging flu season on record could come with some disadvantages. A typical flu season provides clues about the strain that will become dominant next year, giving vaccine manufacturers the ability to adapt next year’s vaccines to a specific strain. Without that knowledge, it may be more difficult to produce a vaccine that matches next year’s strain.
“There is not enough information about the virus circulating in the world,” said Adolfo Garcia-Sastre, director of the Global Health and Emerging Pathogens Institute at the Icahn School of Medicine at Mount Sinai. “As there is so little circulation of the flu, we don’t know exactly which strains, which variants are circulating now. This creates problems with the development of the vaccine and whether it needs to be updated or not. “
David Wentworth, head of the virology, surveillance and diagnostics branch of the CDC’s Influenza Division, said the WHO Global Influenza Surveillance and Response System is still testing between 50,000 and 100,000 samples per week to identify dominant strains.
“The small number of positive samples made it more challenging to identify the ideal vaccine viruses for each of the four main groups of influenza viruses included in most influenza vaccines for the 2021-22 flu season, but it should be noted that O The process of selecting and recommending the vaccine virus does not depend only on the flu viruses currently in circulation, ”said Wentworth via email.
The identification of the next strain also depends on the genetic sequencing of the current strains, post-vaccine serology studies to show which strains may appear next year, forecasting models and vaccine efficacy studies.
The lack of an increase in influenza infections has reduced what could have been paralyzing pressure on the health care system at the height of the pandemic, when more than 100,000 Americans were being treated for COVID-19 in hospitals across the country. And the United States is still recording a large number of deaths caused by what the CDC calls influenza-like illnesses – although in this case, the overwhelming majority are due to COVID-19.
The flu is not going away, and health officials are constantly watching for worrying strains that could become the next threat to human health – WHO said in January that it is looking at an outbreak of H5N6 in China, cases of H1N1 in China and in the Netherlands, H1N2 in Brazil and H3N2 in a child in Wisconsin.
But success in keeping the flu under control this year, doctors hope, will lead to greater acceptance of the vaccine launched in late summer and early fall.
“Those [mitigation] the measures are really working to reduce the spread of infectious respiratory viruses, ”said Garcia-Sastre. “I don’t think we’re going to reduce the cases enough to completely prevent the virus from spreading.”