Infectious disease expert: 'Flu is back with a vengeance'

SAN FRANCISCO -- After a two-year lull due to COVID-19 masking and social distancing, health experts have issued a warning that the flu season is off to an early start and will be back 'with a vengeance.'

UCSF infectious disease expert Dr. Peter Chin-Hong said now that COVID restrictions have been lifted, the door has been opened to a return to a more typical flu season.

"Flu is back, flu is back with a vengeance," he told KPIX 5. "I wouldn't wish it on my worst enemy. It make you feel like you have been hit by a dump truck...It's like a common cold times 100."

Dr. Chin-Hong said the lull has actually weakened resistance to the latest flu strains.

"We don't have a lot of population immunity," he said. "The population in general has not seen the flu for a few years. We are more vulnerable."

While there has not been a sharp rise in flu cases so far this year in the Bay Area, that hasn't been the case elsewhere in the state.

Data from the U.S. Centers for Disease Control and Prevention show that the flu season is off to an early start, with a rash of flu-like cases reported in Texas, parts of the southeast, New York City and Washington, D.C.

One San Diego high school seemingly has a flu outbreak, causing 1,400 students to be absent. The outbreak at Patrick Henry High School started last Monday, doubled on Wednesday. Eventually, more than half the student body call out sick.

"There was a homecoming dance and game on the weekend prior to this Monday," Dr. Howard Taras, a physician for the San Diego Unified School District, told CBS News. "You'd think that it would take several days for them to become infectious to others, but it didn't."

The CDC said prior to the COVID-19 pandemic, there were 36 million cases of the flu in the U.S. With masking and social distancing, U.S. cases plummeted to just thousands — the lowest ever recorded.

But now, most mandates are gone.

"The last two years, people haven't been exposed too much influenza, so their immunity to it may be down," said CBS News chief medical correspondent Jonathan LaPook

 Public health officials are worried the lull has created a false sense of security.  Australia, which experiences winter ahead of the U.S., just had its worst flu season in five years. 

"I don't want to be alarmist, but I am concerned. We know that it's going to be a strain of flu that tends to be more severe," said Dr. Michael Phillips, an infectious disease expert at NYU Langone Health. "For those ages greater than 65, there's a specific formulations of vaccines that you should get and it dramatically reduces the likelihood of hospitalization and death." 

Flu season typically starts in October, peaks in December through February and can last into the spring. Like COVID vaccines, the flu shot may not stop you from getting infected, but the CDC says it can significantly lower the risk of hospitalization and death.