The pandemic dramatically reduced flu cases. That could backfire.

Once the doors open again and people set off without taking the one year worth of precautions for Covid-19, there could be new strains of flu floating around that scientists weren’t expecting, said Cody Meissner, specialist for Infectious Diseases and Pediatrician at Tufts Children’s Hospital, which is also a member of the FDA’s Vaccine Advisory Board. Without a strong enough vaccine, the pandemic-weary country could experience a severe flu season, just like the one resulting from fighting the coronavirus.

“We may have a combination of poor public health interventions at the population level with a low-potency vaccine. And then you might have a mad flu season next year, ”said Lawrence Gostin, professor of global health law at Georgetown University.

Concerns about the impact of the shockingly quiet flu season came to the fore at a meeting of the Food and Drug Administration’s Independent Vaccine Advisory Council earlier this month. While experts suggested that lessons from last year’s flu season could help prevent high rates of flu for years to come, they also struggled to predict what next winter might bring.

“We asked her during that meeting, ‘Has there ever been a moment like this? “Where there was very little flu around and you can then judge what happened the following year, but that’s really unprecedented,” said Paul Offit, a vaccines expert at the University of Pennsylvania and a member of the FDA’s Vaccine Advisory Board.

Influenza is already a difficult virus to track, Gostin said, as it mutates faster than other known viruses like measles. The rapid change in flu causes multiple stresses each year.

The process of predicting which strains of flu will be prevalent each flu season is a global effort. The World Health Organization gathers experts twice a year to predict strains of flu – once each for the northern and southern hemispheres – based on data collected by laboratories around the world. These include the Centers for Disease Control and Prevention, one of the WHO’s six “collaborative centers” for influenza research.

At the Northern Hemisphere meeting in February, experts examine which tribes will then be circulating in the Southern Hemisphere as autumn approaches – and use this information to interpret which tribes could hit the northern part of the world months later. In the US, the FDA Vaccine Advisory Panel is reviewing these recommendations and making a final decision on the composition of the flu vaccines that the agency will license.

Kawsar Talaat, a research fellow at Johns Hopkins with experience in infectious diseases, said experts watch how the virus develops over the season and which strains dominate towards the end of the season.

There are few precedents for the recent US flu season. The 2011-12 flu season set records for the lowest and shortest peak flu levels, according to the CDC. Last season numbers are still only a third of the 2011/12 season rate, the agency reports.

The previous low year didn’t seem to make 2012-13 a particularly bad flu season, Talaat said, adding that the vaccine’s effectiveness this year was in line with or better than most years. She said it was too early to know what the flu season will be like next fall or to predict how likely the flu vaccine is.

“In 2011-2012 we had almost no flu season and that happens from year to year. And then last year we had a three-pronged, three-peaked flu season that was also very unusual. So influenza biology is a fascinating subject, ”said Talaat.

Offit said the low virus levels this season still left sufficient pressure for the FDA advisory committee to select strains for a vaccine and that he was not worried about the vaccine for next fall.

“The belief is that there were enough viruses circulating to be able to select the strains likely to be linked to the flu outbreak next year,” Offit said.

Influenza wasn’t the only winter respiratory virus to have low numbers this season. Respiratory syncytial virus rates had also decreased, according to Offit. The disappearance of respiratory viruses in winter makes health professionals wonder if Covid-19 mitigation strategies could become a necessary tool to fight them off every year.

“I mean, could we reasonably wear masks in a winter month, at least when we are outside in large crowds?” Offit said. “Have we learned this or are we ready to do it or do we feel good when we have hundreds of thousands of cases of hospitalizations for flu and tens of thousands of thousands of deaths? I suspect the answer is B. We are comfortable with this, we are ready to have this, even though we have just learned that there is a way to prevent it from happening. “

People are ready for life to get back to normal, Gostin said, and the fatigue of the Covid-19 pandemic could lead people to give up masking and social distancing at the right time because of the flu.

“Remember, after the 1918 flu pandemic, most people don’t know what happened when that was over. But what happened was the roaring 20s,” said Gostin. “People gathered, mingled, hugged and kissed. All the things that they missed. They huddled in theaters and stadiums and went back to church. That’s probably what’s going to happen this fall, and that makes the influenza virus very happy. “

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