• Children's Center

    Infectious Diseases A-Z: How the flu makes you so sick

a sick child sleeping in a hospital bed with an IV in his or her hand

The influenza season in the U.S. already has claimed a number of lives including at least 30 children, according to the Centers for Disease Control and Prevention. "Influenza A, H3N2, which tends to cause more severe epidemics, is the most prevalent virus circulating this year,” says Dr. Pritish Tosh, an infectious diseases specialist at Mayo Clinic.

Watch: Dr. Pritish Tosh discusses what sickens people.

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"People often forget that tens of thousands of Americans will die each year from influenza infection. The vast majority of those who die are those who have underlying medical comorbidities," says Dr. Tosh. "They have heart disease or lung disease, and influenza tips them over. And they end up dying from their underlying medical comorbidity, or chronic illness."

Inflammatory response

"We also see flu deaths in otherwise healthy people. Many of these deaths are related to the severity of influenza," says Dr. Tosh. "People can get really active inflammatory response from their body as a reaction to the influenza infection and can develop a bacteria superinfection."

"They may develop viral pneumonitis, viral infection of the lungs with influenza followed by a bacterial infections," says Dr. Tosh. "They may end up severely ill, and potentially even dying."

Multiple influenza viruses

There is still a chance of getting infected from the circulating H3N2 virus. Dr. Tosh says, "There are also other influenza viruses circulating throughout the winter , as well. So if someone has not gotten their flu vaccine, they should get it as soon as they possibly can."

The CDC is able to track pediatric flu deaths because individual states must report flu-related child deaths in the U.S. through the Influenza Associated Pediatric Mortality Surveillance System. States are not required to report flu-related deaths of those over the age 18. Many deaths, especially in those over age 65, are from complications brought on from the virus. The CDC says, "Only counting deaths where influenza was included on a death certificate would be a gross underestimation of seasonal influenza’s true impact."

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