FARGO — Health experts are warning that the worst flu season in several years could emerge now that precautions against the coronavirus, which helped subdue flu cases the last couple of years, have ebbed significantly.

In the southern hemisphere, which often provides a preview of the coming flu season in the United States, influenza cases are up sharply, underscoring the need to get flu shots, infectious disease specialists and public health officials said. 

Flu cases are higher than usual in Australia, South Africa and Portugal, which has a well-vaccinated population. “That got people’s attention,” said Dr. Tracie Newman, health officer at Fargo Cass Public Health At the same time, the ever-mutating coronavirus keeps producing new variants, and protection from previous natural infection or vaccination wanes over time, so people should stay up to date with booster shots, they said.

“We basically have a lower level of population immunity now,” Newman said. “The two things that people in our community can do to best protect themselves and others this fall is to receive their bivalent COVID-19 booster, when eligible, along with their seasonal influenza vaccine.”

Those ages 5 and older who have previously been vaccinated against COVID-19 are eligible for the new bivalent vaccine, which protects against the original virus as well as the now-dominant BA.4 and BA.5 variants.

Combined with an uptick in cases of RSV, or respiratory syncytial virus, late fall and winter are shaping up to be an active time for respiratory viruses. The Centers for Disease Control and Prevention reported respiratory viruses are appearing earlier, and in more people, than usual.

Influenza can cause serious illness, especially those who are immunocompromised, the very young and the old, Newman said. Every flu season, some otherwise healthy children die from the infection, she said.

Typically, flu season arrives in December and peaks in winter, but people should keep in mind that it takes about two weeks for the shots to provide maximum protection, Newman said.

After a slow start, more people have been getting their flu shots, with some getting COVID-19 boosters at the same time, said Dr. Avish Nagpal, Sanford’s chief infectious disease specialist.

“It looks like we had a slow uptake, and it’s picking up gradually,” he said. “That’s not unusual.”

Reluctance of people to stay up to date on their COVID-19 vaccinations is worrisome, Nagpal said, noting many are not current.

That’s probably because people’s risk perception is down because the omicron variants, while more infectious, are less likely to produce serious illness resulting in hospitalization or death, he said.

Health providers and public health officials also worry pandemic fatigue has settled in, resulting in decreasing COVID-19 vaccination uptake.

COVID-19 cases are spiking in Europe, which often provides a preview of pandemic waves that later sweep the United States, said Dr. Bertha Ayi, an infectious disease specialist at Essentia.

Because many people have some degree of immunity, from natural infection or vaccination, the U.S. might avoid a big surge, she said.

“It’s possible we may not experience any big wave,” Ayi said. “I’m hoping not.”

Concerns about COVID- 19 may spur some to update their vaccines, and that could help to spur more flu shots, she said, adding, “Hopefully we’ll be a more resilient population come this winter.”

Some have questioned the need for repeated COVID-19 vaccinations, but vaccines often require a series of shots, Ayi said.

Tetanus shots should be updated every 10 years, for instance.

“Many of our vaccines are part of a series, I think people forget that,” Newman said. “It’s not unusual to require multiple doses.”

Fortunately, supplies of vaccine and antiviral medicine are ample, and clinicians now are well versed in treating COVID- 19 and have a long familiarity with influenza, Nagpal said.

“We are not flying blindly with COVID and influenza,” he said. “We are not anticipating a crisis.”

But there still are unknowns about how COVID-19 will behave over the next few years, and if immunity wanes among large numbers of people, the virus has more opportunities to mutate, Nagpal said.

“There is still work to do,” he said.

Readers can contact Forum reporter Patrick Springer at 701-241-5522 or pspringer@ forumcomm.com.