At least 20 people, including the elderly and children, have been hospitalized for seasonal influenza already this year in Wisconsin, prompting state health officials to advise residents to get flu shots.

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3D influenza/CDC

“The best way to help protect yourself from complications that can be caused by the flu, such as pneumonia or hospitalization, is to get the flu vaccine,” said Karen McKeown, State Health Officer. “At this point in the flu season, we normally have one or two people who have been hospitalized due to seasonal influenza; however, this year 20 people have already been hospitalized. We are monitoring the situation and getting the word out about the importance of being vaccinated.

“By getting a flu shot, you are not only protecting yourself, you are also protecting loved ones who may be in a high-risk group,” McKeown said.

According to the Centers for Disease Control and Prevention, everyone aged six months and older should be vaccinated annually.

Flu season for Wisconsin generally runs from late October to May, with peak activity around late January or early February.

Influenza is a contagious respiratory disease caused by a virus. The flu vaccine helps prevent complications that can be caused by the flu, such as pneumonia or hospitalization. With few exceptions, officials recommend that individuals aged six months and older be immunized. Getting vaccinated against influenza is especially important for people aged 50 and older, and those with underlying health conditions. Getting vaccinated is equally important for those who have frequent contact with young children, as children are hospitalized or die from flu complications each year in the U.S.

In addition, Wisconsin reported the country’s first influenza A (H3N2) variant (H3N2v) virus in a person who reported close contact with swine in the week prior to illness onset. The 2014-2015 influenza season began on September 28, 2014.

H3N2v is a non-human influenza virus that normally circulates in pigs and that has infected humans. Viruses that normally circulate in pigs are “swine influenza viruses.” When these viruses infect humans, they are termed “variant” viruses.

Symptoms of H3N2v infection in people are similar to those of seasonal flu viruses and can include fever and respiratory symptoms, such as cough and runny nose, and possibly other symptoms, such as body aches, nausea, vomiting, or diarrhea. Infections with influenza viruses (including variant viruses like H3N2v) can sometimes cause severe disease, even in healthy people. This can include complications, such as pneumonia, which may require hospitalization, and sometimes results in death.

People who are at high risk of developing complications if they get influenza include children younger than 5 years of age, people 65 years of age and older, pregnant women, and people with certain long-term health conditions, such as asthma, diabetes, heart disease, weakened immune systems, and neurological or neurodevelopmental conditions.

Related: Flu season 2014-2015: Flu vaccine composition, dosage and availability