In-Depth: Why the upcoming flu season could be especially severe

'COVID and flu could re-emerge simultaneously'
As Americans begin to remove masks, experts warn cold and viruses could return with a vengeance.
Posted at 6:08 PM, Jun 17, 2021
and last updated 2021-06-17 21:37:42-04

SAN DIEGO (KGTV) -- As pandemic restrictions ease after more than a year, public health officials say vaccinated Americans should prepare to get at least one more shot in the coming weeks: an influenza immunization.

Epidemiologists warn the upcoming flu season could be especially severe. Flu cases dropped to historic lows during the pandemic, meaning millions of Americans did not refresh the protective antibodies they otherwise would have.

“Many of us are susceptible for the coming flu season because we didn't have a flu infection last year,” said Dr. Ali Mokdad, a professor at the Institute for Health Metrics and Evaluation at the University of Washington.

Shortly after states implemented COVID-19 restrictions on gatherings, closed schools and implemented mask mandates, flu cases plummeted and never returned.

“There are so few influenza illnesses that have been reported since the pandemic started that we're not even really keeping a running count,” said Dr. Emily Martin, an epidemiologist at the University of Michigan who tracks flu trends.

Typically, the U.S. sees about 30 million to 50 million influenza infections per year, she said. From September 2020 through late-April 2021, the Centers for Disease Control and Prevention reported a little more than 2,000 laboratory-confirmed influenza cases, an historic low.

With schools reopening, travel returning and more Americans returning to a life without masks, experts worry influenza will strike in a major way.

Dr. Martin said influenza is notoriously difficult to predict, but there is at least one early indicator we could be in for a rough season. Cold-causing respiratory viruses like RSV that normally emerge in the winter have already started circulating in southern U.S. states, well ahead of schedule.

“We're seeing some unusual patterns with some other respiratory viruses that would suggest that maybe we could have flu at an unusual time,” she said. “If that were to happen, we may end up out of sync with our vaccination schedule in a way that would make flu scarier than usual.”

The nightmare scenario for public health experts is that influenza could return early in the summer before the latest generation of flu shots is widely available, Dr. Martin said.

There is also the potential for a resurgence of influenza and COVID-19 at the same time.

In the near term, IHME predicts daily COVID-19 cases and deaths will continue to decline for the next few months, but the institute’s latest model predicts cases will modestly increase around mid-September. IHME is currently working on a new model to forecast the impact of flu and COVID this winter, Dr. Mokdad said.

“We could deal with two outbreaks or epidemics at the same time,” said Dr. Mokdad. Such a “double burden” could once again threaten to overwhelm hospitals, he said.

“It all depends on our vaccination rates coming into winter and Americans' willingness to roll up their sleeves,” he said.