Does uptick in flu reports mean increased flu cases?
April 4, 2019
Clinical data from Haines’ SEARHC clinic indicates that perceptions of the 2019 flu season may be more complicated than it appears.
Media has reported a dramatic 2019 flu season. Anchorage’s KTUU said that cases have skyrocketed, Fairbanks Daily News-Miner called it an “epidemic,” and the Juneau Empire wrote, “It looks like a lot of Alaskans resolved to get the flu in 2019.” The number of reported cases more than doubled from last year. But while Alaska Department of Health and Social Services is witnessing a high number of reported flu cases, the reason for the uptick is more complicated than it appears, according to some experts.
Of Southeast’s 650 reported flu cases this season, the local SEARHC clinic reported 27 of them. SEARHC public relations specialist Stacy Smith said this represents a 24 percent increase of influenza from the previous year. Between March 2017 through March 2018, there were zero positive results out of 29 tests. In the following year there were 27 positive results out of 112 tests. The increase in the incidence of flu is proportional to the increase in the number of tests administered.
“It’s really almost exactly relative to the number of people that got tested. I’m no statistician, but if you look at it, I don’t know that you can necessarily say that ‘Oh, there’s been more flu cases,’” Smith said. “There’s not really this big spike of tons more positive (cases) compared to the number of tests,” she said.
SEARHC’s data throughout Southeast shows a 16 percent increase in positive results this year. Smith said that those results aren’t indicative of a regional trend. SEARHC operates in places with varying access to healthcare, and there may or may not be other places where people could get tested.
The broader landscape of the 2019 flu season follows a similar pattern to the one Smith noticed in Haines. Carrie Edmonson, Influenza Coordinator for the State of Alaska Infectious Diseases Division said she thinks more clinics are providing data to the state.
“I’ve kind of pondered this and I don’t think that we technically had more flu, per se, I just think that we’ve reached out to a lot more providers to report to us.”
The division sends its information to the Center for Disease Control (CDC), and contrary to other news reports, the CDC is reporting minimal influenza-like illnesses in the state, with localized increases in activity. This matches Edmonson’s assessment that, “We have had our little clusters here and there, but again I just think it’s more of the reporting.”
Jayme Parker, Lab Manager at Alaska State Virology Laboratory (ASVL) says that different strains of influenza might also cause reports to change. Three strains of influenza dominate flu season from year to year. Parker said Haines is having an H1N1 year. “When we have seasons with that virus there tends to be a lot of cases, so I can’t really say they’re abnormal.”
ASVL’s weekly snapshot shows that the two previous seasons were dominated by the H3 influenza strain, and the state hasn’t experienced a prominent H1N1 outbreak since 2015.
Parker’s lab has not reported more positive cases of influenza this year, “because we’re under a pretty tight state budget and can’t report more than about 5,000 specimens per year.” ASVL tests the bulk of those during flu season, and Parker said they tested 3,000 from the end of February through March.
Epidemiology at Alaska Health and Human Services, which produces the statewide influenza reports, receives an unlimited number of rapid test results, but they don’t receive the specimens themselves. Their reports do not compare the number of tests administered to the positive test results.
“We just kind of focus on lab confirmed and the concrete data on that,” said Edmonson. The data analysis required to paint a more accurate picture of influenza in Alaska, “just kind of gets into the weeds and we just don’t have time to do it,” she said.
As for those in Haines, “If you got the flu vaccine, you’ve got a better chance of not getting the flu,” Parker said.