Three children have died in Minnesota due to the seasonal flu. About seven children are being treated in the intensive care unit.

Influenza, or more commonly known as flu, is an infectious disease that is caused by the influenza virus. Flu activity is normally unpredictable but it peaks in the months of January and February in the U.S. However, the Centers for Disease Control and Prevention (CDC) suggest that flu activity in the U.S. can start as early as October and affect people until May.

Minnesota health officials have reported that this year's dominant flu strain H3 has already claimed three lives in the state. Healthcare providers suggest that the strain is dangerous and may create life-threatening situations, especially to children.

"We have about seven children right now in our intensive care unit receiving treatment for complications related to this flu virus, and we might even set a record for the number of cases treated in December," says Patsy Stinchfield, Director of Infection Prevention and Control.

Stinchfield explains that the virus can quickly get in a person's blood stream and also move to the brain. The virus can have meningitis-like symptoms and may lead to death - even for healthy teenagers.

Even though flu vaccine is readily available in the U.S., Stinchfield reveals that the vaccine is not very effective to treat this year's flu strain. H3 strains of flu are not new but they emerge every few years. Flu strain H3 is quite dangerous and results in more hospitalizations and deaths when compared to other strains. Around 90 percent of this year's flu cases are the H3N2 subtype.

Health agencies in the U.S. are stressing the importance of getting flu vaccines to avoid flu infections.

"CDC recommends an annual flu vaccine for everyone 6 months and older," per CDC. "Vaccination also prevents flu-related hospitalizations and deaths. While some of the viruses spreading this season are different from what is in the vaccine, vaccination can still provide protection and might reduce severe outcomes such as hospitalization and death."

Healthcare agencies are trying to spread awareness on flu vaccines to reduce infections. However, CDC suggests that less than half of adults and children were vaccinated by early flu season, or early November 2014.

Vaccines are not 100 percent effective but medical experts suggest that getting a flu vaccine can reduce the severity of the infection, which can prevent hospitalizations or even deaths.