The CDC Is Investigating a Flu Outbreak at University of Michigan—Here’s Why
The University of Michigan is facing a massive flu outbreak—there have been 528 cases of influenza diagnosed by the school’s University Health Service.
The Center for Disease Control and Prevention (CDC) is investigating the outbreak to learn more.
Experts discuss what this could mean for this year's flu season.
The University of Michigan is facing massive flu outbreak at a time that flu activity in the country is generally low. The outbreak is so large that the Centers for Disease Control and Prevention (CDC) has sent investigators to try to learn more.
Since the first positive flu case was detected on October 6, there have been 528 cases of influenza diagnosed by the school’s University Health Service—and 77% of those were in people who did not get their flu shot, according to a University of Michigan news release.
Cases of the flu, which has been specifically IDed as the influenza A(H3N2) strain, increased over the last two weeks, with 313 new cases detected the week of November 8, and 198 new cases the previous week. The latest test positivity rate is 37%.
Why is this outbreak concerning?
By comparison, the national flu case percent positivity rate is 0.3%, according to CDC data. Data from the CDC is lagging a little, but currently show that there were just 211 new cases detected in the entire country the week of October 31. Meaning, this outbreak is currently well above current nationwide flu trends.
University of Michigan officials are urging the entire school community to get their flu vaccine “as soon as possible,” the news release says. The CDC will be evaluating the flu vaccine’s effectiveness, risk factors for the spread of the virus on campus, having people fill out questionnaires, and collecting samples from flu patients.
Why is the CDC getting involved?
But why is the CDC involved, again? “While the timing of these recent flu outbreaks is not particularly unusual, it is the first significant flu activity we have seen since March 2020,” Vivien Dugan, Ph.D., acting director for CDC’s Influenza Division, told Prevention in a statement. “Flu vaccination remains important as we enter the holiday season, especially because early data show flu vaccine uptake among some groups is lower this season than last.”
Infectious disease experts say it just makes sense for the agency to investigate this outbreak.
“We’ve only had very scattered influenza cases so far, and this is a large outbreak in a defined population very early in the season,” says William Schaffner, M.D., an infectious disease specialist and professor at the Vanderbilt University School of Medicine. “There is CDC interest in going out, taking samples of the flu viruses to determine which strains are involved, and to really look at this in a semi-enclosed population.” This analysis, Dr. Schaffner says, “may give them some early sense of how effective this season’s vaccine is.”
It’s important to point out that last year’s flu season was practically non-existent, says infectious disease expert Amesh A. Adalja, M.D., a senior scholar at the Johns Hopkins Center for Health Security. Between October 3, 2020 and July 24, 2021, the CDC saw just 2,136 positive flu tests out of 1.3 million specimens tested by laboratories, according to official data published by JAMA. The data show that there were 736 deaths from the flu, too. Compare that to the 2019-2020 flu season, when there were an estimated 35 million flu-related illnesses and 20,000 flu-related deaths, per CDC data.
“We haven’t seen flu outbreaks for some time,” Dr. Adalja says. “There’s a desire to really understand the epidemiology of flu now that it’s come back. Flu has been a mystery for several seasons and there’s a lot of interest in understanding what’s happened to it and to understand the sequence of the virus. People are really trying to understand the evolution of the flu during this pandemic.”
Given that flu activity has been fairly low across the country, what’s happening right now at the University of Michigan could help give researchers some clues as to what will happen nationwide as the season progresses, says Thomas Russo, M.D., professor and chief of infectious disease at the University at Buffalo in New York. “Hopefully, this won’t be a harbinger of a very nasty flu season ahead of us,” Dr. Russo says. “That would be problematic because we haven’t shaken COVID. There is a possibility of a twin pandemic—flu and COVID-19—that didn’t happen last year.”
How can you protect yourself against the flu?
If you happen to find yourself in an area where flu cases suddenly ramp up, experts recommend following COVID-19 prevention measures—which also help protect you against the flu. “Put your mask back on and do as much social distancing as you can,” Dr. Schaffner says. “Practice good hand hygiene, and certainly try to avoid anyone who is coughing and sneezing.”
It’s also crucial to get the flu vaccine, if you haven’t already, Dr. Adalja says. “The vaccine takes two weeks to kick in,” he points out, so you’ll need to be especially cautious in the meantime.
And, if you’re at high risk for flu complications (meaning, you’re pregnant, elderly, or have certain underlying health conditions), Dr. Russo recommends talking to your doctor about taking oseltamivir (Tamiflu) if you’ve been exposed to someone with the flu, as an added layer of protection.
“People should not be complacent because we had a virtually nil flu season last year,” Dr. Russo says. “This outbreak is a warning that flu is back.”
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