H3N2 Influenza Strain Hitting Hard This Year


January 18th, 2018

Viral infections, like influenza, are spreading throughout the world with increasing speed. As people travel between countries and continents, they can unknowingly carry viruses, spreading them to others. We were reminded how quickly this can happen in 2009, when the H1N1 flu virus affected millions of people worldwide. In the United States, all 50 states had reported H1N1 infections by June of 2009, and thousands of people had developed complications like pneumonia or sepsis. The scenario was repeated during the severe flu season of 2015 when, according to the Centers for Disease Control, 29.9 out of every 100,000 hospitalizations, were flu-related.

The 2017/2018 flu season is proving to be another nasty one. This season, the main flu virus is the H3N2 strain, which is known to cause the worst influenza outbreaks.

There are different types of influenza. The annual seasonal influenza  (maybe include the HN designation for the seasonal influenza or type here).  is the most common one. There are also different types of viruses:

  • Type A: Type A influenzas affect both people and animals. The animals, such as birds, help spread the virus. The type A flus are the ones that cause most of the flu pandemics or epidemics. In 1918, the world was hit with the “Spanish flu,” which killed millions of people. It was feared in 2009 that the H1N1 virus would have a similar outcome.
  • Type B: Type B influenzas do not infect animals and don’t cause epidemics or pandemics. They are generally not as serious as the type A flu, but they still can cause harm on occasion. 
  •  Type C: Type C influenzas are milder than either types A or B. They don’t cause epidemics or pandemics and they only affect humans.

Unlike viruses like chicken pox or measles, the viruses that cause influenza can change and mutate, turning into new viruses. If you contract the flu one year, you can get it again the next – because the virus has changed enough from the year before that your body doesn’t recognize it and you are not immune.

Flu strains are composed of subtypes. There are 16 subtypes of hemagglutinin (the “H”) and nine subtypes of neuraminidase (the “N”). These are used to name the various types of influenza, such as H1N1 and H3N2.

Influenza vaccinations cut down the risk of contracting the flu. Some years the vaccine is more effective than others, but experts still encourage vaccinations when the effectiveness rate is lower. Reports indicate that people who may still contract the flu despite receiving a vaccination often experience less severe symptoms, fewer complications, and shorter duration of illness.

To learn more about how influenza may put you at risk for complications, including sepsis, visit Sepsis and Influenza.