Those looking to know whether the worst of flu season has passed may be disappointed to find out that the most predictable thing about flu is that it’s unpredictable, according to Dr. Tom Frieden, director of the Centers for Disease Control and Prevention.
“There could be another bump, and there could be another peak, or we might have been through the worst of it,” Craig Roberts, an epidemiologist for University Health Services, said. “You never know.”
Generally, flu season begins in October and ends in March, with the number of cases reaching a peak level at different points each year.
Despite heightened concern about flu around the country in mid-January, this flu season doesn’t appear to be anything unusual for UHS, Roberts said. He described the 2012-’13 season as moderate and not particularly severe, but still encouraged students to get vaccinated.
Nationally, as of the week ending Jan. 26, a lower proportion of people were seeing health-care providers for influenza-like illness, but as of that weekend, the proportion remained above baseline levels, according to the CDC.
UW-Madison appears to be following national trends with a two-to-three-week lag, Roberts said, so numbers on campus could drop soon.
Or not. It’s hard to determine how the season will pan out.
“Every year is different in terms of both timing and volume and severity and which strain is gonna predominate and who’s gonna get the sickest,” Roberts said.
Two to three different strains of the flu circulate among the population annually, with one strain causing the majority of cases.
This year’s dominant strain, H3N2, has been associated historically with more severe flu seasons, Dr. Frieden said in a press conference.
According to Roberts, how severely a flu virus affects the population also varies among individuals.
“I would say there’s more variation between people than there is between viruses,” Roberts said.
Other strains of flu circulating this year include H1N1 and a type B flu.
Strains of the flu are labeled type A, B or C based on their nucleic acids and protein composition. Both H3N2 and H1N1 are type A strains of influenza. Type C strains of influenza are found in humans but do not cause widespread outbreaks, whereas types A and B do.
Each year, scientists create a new seasonal flu vaccine that targets what they predict will be the dominant strains in the population come flu season. Generally, an annual flu vaccine is designed to fight against the dominant A strain, B strain and the 2009 H1N1 virus.
According to the CDC, this year’s vaccine shows a 62 percent effectiveness, meaning those who receive the vaccine are 62 percent less likely to contract the flu this season.
Roberts advised students who are experiencing influenza-like illness to stay at home for 24 hours after fever has resolved and encouraged students to get a flu shot.
Flu symptoms include fever, sore throat, runny nose, headache, fatigue and muscle aches. People contract the flu by breathing in droplets exhaled by those infected with the virus. Someone with the flu can spread it to a person up to six feet away.
“Influenza is not a cold,” Roberts said. “It’s a much more serious illness, and people who’ve had it can tell you it tends to feel more like you’ve been hit by a truck.”
UW-Madison students can receive flu shots for free by calling UHS to make an appointment.
