With classes and homework starting again, there are plenty of things students have to worry about coming into the spring semester. This season, however, there is another item everyone should be adding to their list of concerns: the influenza virus.

Influenza is defined by the Centers for Disease Control and Prevention as a respiratory illness caused by influenza viruses. Severity of the flu can vary from cold-like symptoms all the way to a severity that could require hospitalization and even result in death.

The virus is spread as an aerosol, meaning it can be transmitted through things like coughing, sneezing and talking. An individual can become infected by breathing in the same air or coming in contact with a surface that has been contaminated by the virus.

Though cases of influenza break out every year, the virus has always been of particular concern because it is constantly changing and producing new strains.

According to Robert Belshe, Adorjan endowed professor of medicine, pediatrics and molecular microbiology and director of the Division of Infectious Diseases and Immunology in the Saint Louis University School of Medicine, “Influenza is a rapidly-developing virus that evolves from year to year because humans have the antibodies to guard against the virus. So as it evolves, it selects for novelty, something humans have no antibodies against. From year to year, it is constantly changing.”

Influenza, or the flu, has struck the nation particularly hard this year. According to the CDC, during the first week of the new year, nearly all states reported either widespread or regionally situated cases of the flu. In the state of Missouri, the number of confirmed cases of the flu is above average for this time of year and the virus started appearing earlier in the season than in recent years.

The virus is at a widespread level, meaning there has recently been an increase in lab-confirmed cases of influenza in at least half of the state’s regions.

According to Nancy Delaney, a full-time physician in Student Health and Counseling, the best thing to do to guard against influenza is to get the influenza vaccine.

“Get the flu shot. People often say ‘I never get the flu, so I don’t need it,’ but everyone should definitely get the flu shot,” Delaney said. “Once you’ve had the flu, you’ll never want it again. You just feel awful. The vaccine is definitely a worthwhile investment.”

The influenza vaccine is developed on a yearly basis depending on which strains of the virus are expected to be the most prevalent come flu season.

“The World Health Organization and the Center for Disease Control run surveillance every year to see which viruses are circulating and pick strains to put in the vaccination and protect against next year,” Belshe said.

“The Food and Drug Administration then meets to decide which strains to vaccinate against and begin developing the next year’s vaccines.”

This year, the flu vaccine is protecting against three influenza viruses that surveillance has predicted to be the most common during the season, including two strains of influenza A and a strain of influenza B. Typically, according to Belshe, the vaccines will include two A strains and one or two B strains.

According to the CDC, as of Jan. 4, approximately 128 million doses of the vaccine had been distributed.

Once the vaccine is administered, it usually takes about two weeks for the antibodies to develop in the body that will protect against the designated strains of influenza.

Even if you are vaccinated, it is still possible to contract the flu.

This year’s vaccine only protects against three different strains of the flu, but there are other, less prominent strains still in circulation.

As of the first week of January, however, approximately 91 percent of the viruses analyzed at the CDC are like the viruses included in this year’s vaccine.

In addition, the vaccine will not guard against influenza that had been contracted prior to vaccination or during the two-week span it takes for the vaccine to become effective.

The chance of contracting influenza during this period has led to the false notion that it is possible to get the flu from the vaccine itself.

“There are a lot of myths surrounding the shot,” Delaney said. “You can’t get the flu from the flu shot. But, usually, if you do come down with the flu after receiving the shot, it’s because you got it before the shot or before the shot took effect. The worst that can happen from the shot is a sore arm.”

There is also some variation in how effective the shot is once administered.

“The effectiveness of the vaccines depends upon the population being vaccinated,” Belshe said.

“Young, healthy adults have a vigorous immune system response, so the vaccine is particularly effective for them. As people get older, their immune response is not as strong. For young kids, the shot is not as effective, but a nasal spray vaccine works very well.”

According to Belshe, the vaccine is about 60 to 80 percent effective in young, healthy people.

Among the elderly, it is only expected to be about 40 percent effective, but often proves to have a greater effectiveness.

There are few things as effective in guarding against the flu as the vaccination, but there are other little things that can be done to further protect against the virus.

“The single best measure is to keep washing your hands,” Delaney said. “Wash them after opening doors, handshakes and before eating. This will help minimize the chances of getting the flu and spreading it. Keep household surfaces clean and don’t borrow people’s pens. We tell people to cover their mouths when they cough, to throw away used tissues and to minimize contact with people who are obviously ill.”

Students looking to receive the flu vaccine can get it from Student Health.

The vaccine is typically covered by insurance and runs about $20, and walk-ins are welcome.