Flu season is just getting started in Spokane, but public health workers from around the world have been preparing for the fast-spreading virus since February.
The strains of influenza covered by the vaccine vary from year to year; the composition of each year’s vaccine is based on recommendations from the World Health Organization, said Kayla DeBusk, a vaccine accountability specialist with the Spokane Regional Health District.
Around the world, more than 100 countries have influenza centers that monitor flu-like illnesses. The centers test samples from patients to determine whether an illness is caused by an influenza virus, and if so, which type.
Those centers report data to a handful of WHO sites around the world, and those sites in turn track which strains are circulating. In February, the centers’ directors and other experts meet to prepare for flu season in the northern hemisphere.
“What’s circulating in the southern hemisphere kind of gives us a determination of what we might expect to see in our season,” DeBusk said.
Contrary to popular belief, the effectiveness of the vaccine isn’t usually determined by health departments selecting the right flu strains. More often, it depends on whether scientists have a similar virus mapped out well enough to produce vaccines for it.
“We don’t have a good virus match” for some strains, DeBusk said. Typically, a vaccine strain of the flu is about a 40 to 60 percent genetic match to the virus it’s supposed to provide immunity for.
Vaccines are more effective in years when the main types of flu have been seen before and already have effective vaccine strains. Strains for vaccines are grown in hen’s eggs.
Some people believe flu vaccines are rushed or “untested” because they change composition every year, but DeBusk said that’s far from the truth.
“We’ve been doing this method of manufacturing flu vaccines for about 70 years,” she said.
Swine flu, also known as the H1N1 virus, is circulating again this season and has been included in this year’s vaccine, though the variant is slightly different from the one included in last year’s.
In 2009, when the virus first grew into a pandemic it was a latecomer to the season, so scientists didn’t have enough time to include it in that year’s vaccine, said Alexandra Hayes, immunization outreach program coordinator for the health district.
“It was like that rogue player that just came out,” she said.
Flu vaccines typically come in two forms: the trivalent, which includes three flu strains, and the quadrivalent, which has four. Most doses are trivalent.
All vaccines protect against two types of influenza A, which can be transmitted from animals. Those viruses, including H1N1, make up most cases during the early part of flu season. Influenza B strains, which only affect humans, tend to pick up later in the season.
Quadrivalent vaccines include two types of influenza B, while trivalent vaccines have just one.
It’s nearly impossible to predict how bad a given flu season will be, but the past two have had higher numbers of hospitalizations and deaths in Washington than is typical, Hayes said.
Three people in Spokane County have already been hospitalized for influenza this season, the health district said. No deaths have been reported in Washington.
Last season, the U.S. made almost 146 million doses of flu vaccine, DeBusk said. But many people still believe they don’t need to get vaccinated because they’re healthy.
Aside from the fact that healthy people die from the flu every year, she said, it’s important to remember that even healthy people can carry the virus and infect others without showing apparent signs of the flu.
“It’s not for you. It’s for everyone that you encounter in the grocery store, at work,” she said. “If you are carrying a virus type, you could get someone else sick that is immunocompromised.”
It’s best to get vaccinated before influenza viruses circulate because it takes about two weeks to develop immunity through the vaccine. A slight reaction, including flu-like symptoms, is common, but it’s much milder than the flu.
“The viruses cannot actually give you the flu,” Hayes said. “That’s your body responding and making antibodies.”
At Spokane Public Schools, keeping children healthy can be an uphill battle. Recently, a stomach bug has been spreading, but district health services director Becky Doughty said it’s not influenza.
“Parents call everything ‘the flu’ and adults, too,” she said. But influenza symptoms rarely include intestinal or stomach symptoms such as diarrhea and vomiting.
When flu season hits, the district emphasizes hand-washing and keeping surfaces clean. Parents are encouraged to get flu shots, as well as staff and faculty, she said.
“It hits the adults harder a lot of the time, and we also don’t want to be passing it on to kids in the classroom,” Doughty said.
Flu shots are typically offered from September to mid-November. Shots are available through local health care providers, pharmacies and grocery stores.