This year, a familiar virus has shown up in the labs of the Alabama Department of Public Health. Sherri Davidson, an epidemiologist for ADPH, monitors the spread of influenza virus in Alabama by taking flu specimens and identifying which strain they carry. The familiar virus she’s been seeing is H1N1, which has previously made headlines as a pandemic in 2009.

That in itself is neither unusual nor particularly dangerous – H1N1 has been around before with predictable consequences. What is unusual is that H1N1 is all she’s been seeing.

“The most unique thing about this year is that so far we’ve only seen one strain circulating,” she said.

Typically, there is one dominant strain, which accompanied by a sprinkling of other strains. This year, only H1N1 has been identified in Alabama.

Even back in 2009, Davidson said, there was nothing inherently more severe about the H1N1 virus. What made it destructive was that it was a new strain that then proceeded to go “viral.” This year, it’s not new. It’s seasonal.

“It’s now considered to be one of the seasonal influenzas because it’s been in circulation ever since then,” she said. “The flu that we’re seeing in Alabama that we’ve seen identified at our state lab is in all of our vaccines.”

While robbed of its previous power, the H1N1 virus has returned with one distinctive trait intact. During its pandemic run, Davidson said, the virus was notable because it infected those who were traditionally less vulnerable to infection, such as college-aged students.

Davidson said she’s seeing the same trend this year. The virus prefers young adults and healthy adults.

Nationally, H1N1 is dominating flu cases in similar fashion. Jason McDonald, a health communications specialist at the Centers for Disease Control and Prevention, said the virus is back in larger proportions than before. In the 2012-2013 flu season, it only made up 6 percent of Type A samples, one of the two seasonal flu types. In the 2010-2011 season, immediately following the pandemic, it represented 38 percent. This year, it represents 97 percent of type A samples.

This resurgence also echoes the 2009 season, deviating from the normal pattern.

“Of the hospitalizations reported to CDC so far this flu season, 61.6 percent have been in persons aged 18-64, which is somewhat uncommon for seasonal flu but similar to what was observed during the H1N1 pandemic,” he said. “Typically, between 50 and 60 percent of hospitalizations occur in people over 65.”

Part of this, McDonald said, may be due to the fact that younger people are less likely to be immunized. The CDC estimates that under a third of those between 18 and 49 were vaccinated, almost 10 percent under the national average.

“During the pandemic, older people were less likely to get sick, probably because they had pre-existing immunity from earlier viruses that were like H1N1,” he said. “Younger people do not have this pre-existing immunity, and they are also less likely to get vaccinated.”

Elizabeth Cockrum, a UA professor of pediatrics, said while college students are generally a healthy population, less than desirable immunization rates allow college campuses to become hotbeds for the virus.

“[Any] environment where large numbers of individuals are housed or grouped together increases an person’s chances of acquiring the virus from others,” Cockrum said. “This would include places such as dorms, large classroom, student centers and gyms – any place where large numbers of students would congregate.”

The typically low vaccination rates led the University to research what was keeping them, and the faculty and staff on campus, from getting the most effective method of prevention.

“The top factors were cost and convenience. Therefore the vaccination strategy was changed in 2012 by the University. The vaccine would now be offered at no cost to all faculty, staff and students, and medical personnel would make it much more convenient by bringing the vaccine to multiple sites and buildings on campus,” she said. “This change in strategy has resulted in a marked improvement in the UA rate of influenza vaccination.”

The University’s campuswide campaign was organized and implemented by the College of Community Health Sciences. The No Flu Zone campaign and Flu Blast Team, which included Cockrum, were awarded the University’s Sam S. May Commitment to Service Award in 2012. President Judy Bonner, who presented the award, mentioned the administration of 7,000 vaccines.

This year, the campaign administered 7,500 shots, a number Cockrum said can still grow.

“[It is] still not too late,” she said. “If someone has not been immunized they can still come to the SHC or UMC for their vaccination.”

Davidson also stressed the importance of the vaccination. Another vaccine will be available for next season, but students are encouraged even now to get a flu shot. The flu season is in fact, she said, a misconception.

“It does circulate year-round,” she said. “There’s no way to predict when it’s going to be most active.”

Flu vaccines and the strains they cover are derived from investigating patterns in the Southern hemisphere, which gets hit with winter and the flu first.

“We kind of get a preview of what our winter influenza situation is going to look like,” she said.

Despite the changing composition of the flu, Davidson advocated a class approach to controlling the virus. If you’re sick, stay home.

“Cover your cough,” she said. “And wash your hands.”