Influenza Strain Circulating in Alberta Causes Severe Illness in Vaccinated Populations


The H3N2 strain of influenza continues to circulate throughout Calgary, as well as in the South Zone, while “little influenza activity in the North Zone [has been observed] to date.”

Usually, the flu vaccine is administered to provide extra protection against influenza infection. However, a strain that is currently circulating in parts of Alberta, Canada, has caused serious illness in many individuals as well as several deaths, even among those who had received vaccination against the season’s strain of the virus.

For the 2016-2017 flu season, the Centers for Disease Control and Prevention (CDC) recommends administering the flu vaccine to all individuals older than 6 months of age. Those with egg allergies or Guillain-Barré Syndrome should consult their doctor before receiving the flu vaccine. The CDC also recommends that women who are pregnant should receive the vaccine. Not only this, but in the event of a vaccine shortage, the CDC is recommending that pregnant women and women who have delivered within the past 2 weeks be among those for whom flu vaccines should be prioritized. Although some believe that administering the flu shot to pregnant women may cause autism spectrum disorder in developing fetuses, a recent study has debunked this myth.

According to Alberta Health, the influenza H3N2 strain is currently circulating the province. This particular strain is a variant which was initially identified in pigs but later transferred to humans, according to the CDC. The highest number of H3N2 cases in Alberta has been observed in the Calgary Zone as well as the South Zone, while “little influenza activity in the North Zone [has been observed] to date.” There have been 1,036 lab-confirmed cases of infection in Calgary, and more than 300 of these individuals have been hospitalized due to extreme illness. Furthermore, 5 of the 13 Alberta residents who were reported to have died with lab-confirmed flu were from Calgary. (This is a drop from the 55 deaths associated with the flu during the last flu season.)

CBC News Canada reported that there have been about 40 flu outbreaks in the city of Calgary alone, since September. Commenting on the H3N2 flu strain, Medical Officer of Health of Alberta Health Services, Judy MacDonald, MD, stated that this particular strain is “a more difficult one” and can cause the most harm in the elderly.

In addition, Glen Armstrong, PhD, professor in the department of Microbiology, Immunology & Infectious Diseases, at the University of Calgary, states that this particular strain has a high risk of evolving mid-flu season. This causes particular difficulty when it comes to developing an efficient vaccine. He explained, “you can generate a vaccine that is a perfect match for an H3N2 variant, and then as the flu season goes on that variant makes slight changes, which decreases the effectiveness of the vaccine as the flu season goes on.”

However, Dr. Armstrong still recommends receiving the flu vaccine. He states that, although it may not be 100% effective, “you are still going to be better off than if you weren’t vaccinated in the first place.” Receiving the vaccine, according to him, will decrease the intensity of illness as well as hasten recovery.

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