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Despite warnings, a flu season that was not

As the nation suffered through a devastating winter stream of coronavirus cases, the phones rang at Old Dominion Pediatrics in Virginia. Callers with infected family members sought advice on how to quarantine at home so that others do not get sick.

But no one asked about the flu.

And the test results Eric Freeman saw showed that dozens of his patients had coronavirus, but almost none tested positive for the flu.

“COVID has just been the dominant viral pathogen right now, and it has not really allowed the flu enough space to populate adequately,” Freeman said in an interview Monday. “I haven’t had a quick flu test positive in the office since before Thanksgiving.”


Public health experts, GPs and pediatricians had warned for several 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 one funny thing happened in the midst of a global health pandemic: the flu season was effectively interrupted.

Data from the Centers for Disease Control and Prevention (CDC) shows that only 1893 Americans have tested positive for the flu virus this year, between clinical laboratory results and public health laboratories. At this time last year, more than 290,000 people had tested positive for the flu.

The CDC reported in August that 198 children had died of flu-related causes during the last flu season, a record high. So far this year, only one child has died, the lowest number since registrations began in 2004.

“You should never think that there would be silver lining for this [pandemic]”But this is about as close to a silver lining as it has been,” said Peter Hotez, a pediatrician and dean of the National School of Tropical Medicine at Baylor College. “It’s what wears masks and social distancing and probably reduced personal classes [does]. ”

Fewer than 1 in 1,000 hospital admissions this year have been for influenza, a seventh of the proportion who were registered in the last flu season with a low severity in 2011-2012.

U.S. health professionals and vaccinologists usually get important tips about the upcoming flu season from viruses that begin circulating during the winter months in the southern hemisphere, our summer months.

But while these officials sounded the alarm about the potential for a double season of respiratory illness, governments in Australia, Chile and South Africa reported lower-than-normal circulation. Viral curves in the three countries began to decline much faster than in previous seasons, as new locks and restrictions were put in place.

“During the last twelve months, with the exception of some countries in West Africa and some countries in Southeast Asia, there was no flu season. And it is in countries that are closed very strictly, it is in countries that may not have closed down as strictly. It confuses me a little, “said Richard Webby, director of the World Health Organization (WHO) Collaborating Center for Studies on the Ecology of Influenza 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 that causes COVID-19, which means that masks and social distancing are likely to have an even greater impact on the total number of flu cases than on coronavirus. Stopping school meant attenuating one of the most productive vectors of person-to-person transmission.

“Young children and schools are pretty big players when it comes to influenza infection in society,” Webby said. “With many schools that are not open, or the control measures are actually in the schools, it has had a major impact on flu outbreaks.”

And, Freeman said, parents took public health officials’ warnings that their children would get the flu. Although final data on influenza vaccination rates will not be known for several months, Freeman said that in practice, vaccine rates, just south of Richmond, Virginia, were significantly higher than in previous years.

“This was one of the best years I have had in 15 years of vaccination against influenza. This year, the parents were definitely engaged, very enthusiastic, ”said Freeman. “There was a point where I could not have flu vaccines on my shelves.”

Apparently, nothing about the coronavirus pandemic has been easy, and some experts warned that even the least harmful flu season on record could bring some disadvantages. A typical flu season provides clues about the strain that will become dominant next year, which then gives vaccine manufacturers the opportunity to tailor next year’s shoots to a specific strain. Without that knowledge, it can be more difficult to produce a vaccine that matches next year’s strain.

“There is not enough information about the circulating virus 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. “Because there is so little circulation of influenza, we do not know exactly which strains, which varieties 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 department at the CDC’s influenza division, said the WHO’s global influenza surveillance and response system continues to test between 50,000 and 100,000 samples per week to identify dominant strains.

The reduced number of positive samples made it more challenging to identify the optimal vaccine viruses for each of the four main groups of influenza viruses included in most influenza vaccines for the 2021-22 influenza season, but it should be noted that the choice and recommendation of vaccine viruses is not only dependent of influenza viruses in circulation, ”Wentworth said in an email.

Identifying the next strain is also dependent on genetic sequencing of current strains, serology studies after vaccination to show which strains may break out next year, prognosis models and vaccine efficacy studies.

The lack of an increase in flu infections has reduced what could have been a devastating burden on health care at the height of the pandemic, as more than 100,000 Americans were treated for COVID-19 in hospitals across the country. And the United States still records a large number of deaths caused by what the CDC calls flu-like illnesses – but in this case, the vast majority are due to COVID-19.

The flu will not go away, and health professionals are constantly keeping an eye out for worrying strains that could be the next threat to human health – the WHO said in January that they are looking at an outbreak of H5N6 in China, H1N1 cases in China and the Netherlands, H1N2 in Brazil and H3N2 in a child in Wisconsin.

But the success of keeping the flu under wraps this year, doctors hope, will lead to more acceptance of the vaccine that comes out in late summer and early fall.

“These [mitigation] Measures are really working to reduce the spread of infectious viruses that are respiratory tract, Garcia-Sastre said. “I do not think we will reduce the cases enough to prevent the spread of the virus.”

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