Image of the newly identified H1N1 influenza virus, taken in the CDC Influenza Laboratory.
Image of the H1N1 influenza virus, taken in the CDC Influenza Laboratory. Image source: CDC Influenza Laboratory

Flu might be late this year, but don’t let that make you complacent.

By Rose Hoban

This year’s flu season seems to be getting a slow start, say state health officials, so people still have time to get their flu shots and develop immunity before the chorus of coughs and sneezes catches up with you.

Image of the newly identified H1N1 influenza virus, taken in the CDC Influenza Laboratory.
Image of the H1N1 influenza virus, taken in the CDC Influenza Laboratory. Image source: CDC Influenza Laboratory

Epidemiologist Zack Moore, from the state Department of Health and Human Services, also warned just because flu activity hasn’t really started to rise, it doesn’t necessarily mean this year’s season will be less severe.

“Typically, we peak in January or February,” Moore said. “But the last three years, we peaked in the week of Christmas. It was kind of unusual to have it once, let alone three times.

“But this year, we haven’t seen those early indicators.”

Circulating strains

In addition to amping up quickly in December of last year, the 2014 flu viruses were doozys, making people pretty darned sick.

The number of people showing up at emergency rooms and clinics topped the numbers for the prior two years, climbing to as many as 9 percent of all patients by the end of December.

One of the problems last year was that the vaccine formulated to combat the flu wasn’t a good match for the viruses that ended up circulating throughout the population. That was, in part, the result of the time lag that happens every year when the World Health Organization convenes flu experts in February to predict which flu viruses will make people sick eight or nine months later.

Part of the reason that meeting takes place so early is to give vaccine manufacturers time to create, test and distribute the flu vaccine.

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All  of the 2015-16 influenza vaccine is made to protect against the following:

  • A/California/7/2009 (H1N1)pdm09-like viruses
  • A/Switzerland/9715293/2013 (H3N2)-like viruses
  • B/Phuket/3073/2013-like viruses.

Some of the 2015-16 flu vaccine is quadrivalent vaccine, which also protects against an additional lineage of B virus. For this season, that will be a B/Brisbane/60/2008-like virus.


But the influenza viruses circulating around the world through 2014 developed subtle mutations that made the vaccine a poor match to fight them, leaving people vulnerable to the flu even if they were vaccinated.

Moore said the flu strains in this year’s vaccine show no evidence of that kind of genetic drift.

“So far, the viruses that have been characterized in North America are still well matched to the viruses that the vaccine is formulated to protect against,” Moore said. “But time will tell.”

Dr. Zach Moore from the Division of Public Health said this year's flu season was especially hard on people over the age of 65.
Zach Moore from the Division of Public Health said the 2014 flu season was especially hard on people over the age of 65. Image courtesy screen shot of WRAL broadcast

Even with a well-matched vaccine, Moore pointed out, effectiveness is dependent on many factors, including the biology and age of a person who gets the vaccine, what underlying diseases they might have and the virulence of the flu strains that are circulating.

He said even good flu vaccines are only about 50 percent effective.

“I think people misunderstand the 50 percent and say, ‘It’s a 50-50 shot whether I get it or not.’ But that’s not what 50 percent means,” Moore said, explaining that you can still get the flu if you’ve been vaccinated, it just won’t make you as sick.

“Fifty percent means you’re reducing your risk of having to go to the doctor for flu by 50 percent,” he explained.

Watching and waiting

One of the biggest jobs DHHS epidemiologists have every year is watching the flu numbers on a weekly basis. They report on a public website with information about the number of people who have died and how many people show up at emergency rooms and clinics with flu-like symptoms.

North Carolina’s surveillance system consists of automated information coming from emergency departments to state databases and reports from selected physicians’ offices.

Data and graphs courtesy NC DHHS
Data and graphs courtesy NC DHHS

State officials have also tapped more urgent care clinics, said Scott Zimmerman, who heads the state public health laboratory in Raleigh. He said it’s a reflection of the growing popularity of the clinics to treat people with time-limited problems.

His lab also provides test kits for physicians around the state who want to send in a swabbed sample to confirm a diagnosis of the flu.

Moore explained it takes a lot for a death to be attributed to the flu: a doctor has to suspect the flu, take a swab, send in a test and report it to the local health department.

Last year, 218 people were confirmed to have died as a result of flu in North Carolina, reported Anita Valiani, who works with DHHS’ Communicable Disease Branch. But she said the real number was likely higher.

“We know that a lot of people who die because of a flu infection were never tested,” Moore said. “They die of pneumonia or they die of other things, other underlying conditions that are exacerbated by their flu infection.

“They either don’t get tested or it never gets reported.”

Last year, deaths were concentrated in people over the age of 65, with 180 deaths. The 2014 strain that made people sick was a H3N2 virus.

Other strains, such as H1N1, tend to make younger people sick.

“In H1N1-predominant seasons, we see deaths in young adults. Unfortunately, pregnant women seem to be hardest hit,” Moore said.

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