University of Tennessee Medical Center sees early spike in flu cases

The University of Tennessee Medical Center is seeing an early increase in reports of influenza, in part due to the cold weather as well as a low efficacy associated with this year's flu vaccine. 

It's still too early to say whether this winter will be a bad season for the flu, but the hospital has already seen growth in the number of reported cases this month, said Jennifer Radtke, manager for infection prevention at the UT Medical Center.

"It's just one of those years where the (Centers for Disease Control and Prevention) is seeing that this strain of flu is only somewhat covered by the vaccine that was given this year," Radtke said. "They're seeing that it's anywhere from 10 to 33 percent effective, so anytime there’s a mismatch between the vaccine and the circulating strain of the flu, you’re going to see more cases."

How common is the flu this winter?

Vaccine effectiveness varies from year to year, though recent studies show that the flu shot typically reduces the risk of illness by between 40 percent and 60 percent among the overall population when the circulating virus is matched closely to the vaccine virus, according to the CDC. 

According to the agency's most recent weekly flu report, cases of influenza in the U.S. "increased sharply" for the week ending Dec. 16, with the number of states reporting widespread flu activity jumping from 12 percent to 23 percent and the proportion of samples testing positive for influenza at clinical laboratories rising from 8.4 percent to 14 percent.

Peak flu activity in the U.S. usually occurs around February.

Radtke said the UT Medical Center saw an increase in cases in early December and then a much larger increase over the last week. 

As of Thursday, the hospital has seen 67 people who tested positive for the flu this month. In December 2016, 25 people tested positive for the flu at UT Medical Center.

Because only a certain percentage of people with flu symptoms go to hospitals and get tested, it can be challenging to track the actual number of people affected, Radtke said.

False negative results for flu tests are also common, so it’s likely the number of people with the flu is much higher.

Radtke said cold weather often leads to such an increase, especially as more people are staying indoors and are in close contact with others who may be sick, but that the cold isn't the only factor at play.

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"It's not uncommon to see it this time of year," she said. "The last couple of years we didn't see it in December, but a few years back we did. Cold weather doesn't hurt, but we've had cold Decembers before and not had flu." 

Don't get sick. Wash your hands.

For those who are sick or want to avoid the flu, Radtke said it's important to remember to stay home if you are sick, wash your hands frequently, and if you do get sick, quarantine yourself to a certain room or area of your home.

"If you're in public places and you're not sick, frequent hand hygiene, washing or sanitizing your hands is essential," Radtke said. "If you’re in the grocery store, consider wiping off the handles of the cart. Stay away from sick people. That helps a lot."

It also pays off to stay well rested and hydrated so that if you do come in contact with the virus, your body is prepared to fight it off. 

It's also not too late to get the flu vaccine.

"Even though the efficacy might only be 33 percent this year, that means three out of 10 people will be protected by it," Radtke said. "And if you do get the flu and you’ve had the vaccine, you’re more likely to have a less severe case. You will get some coverage from it."