Flu shot doesn’t match up well against this year’s strain

H3N2 virus has mutated since vaccine was developed, Health Canada agency says

Canadians who have received the flu shot are still susceptible to the season’s most common influenza strain, according to the Public Health Agency of Canada.

The H3N2 influenza virus has mutated since this year’s flu vaccine was developed. The agency’s FluWatch program reports that a majority of the strain’s cases are not optimally matched to the vaccine’s version of the strain.

Toronto is experiencing a larger than usual number of flu illnesses. City public health data show that the 152 new lab-confirmed influenza cases in the city during the week ending Dec. 20 exceeds the 10-year average for the time frame. The number was also up from 116 cases in the week previous, bringing the total number of season’s cases to 456.

Reported institutional outbreaks and absences of children from schools in Toronto were also higher than normal.

Oakville Trafalgar Memorial Hospital experienced an outbreak of the H3N2 strain earlier this month.

Canada’s public health agency reports that flu cases result in approximately 12,200 hospital visits and 3,500 deaths every year. The majority of such cases involve patients who are at least 65.

Vaccines are designed each year in anticipation of the flu season’s most common strains. They usually in- clude three or four types of the virus.

The agency maintains that the vaccine is still the best method of flu prevention, and recommends it to everyone over six months old. Despite the H3N2 mutation, it says the vaccine still provides some protection and remains effective against other strains.

Influenza symptoms typically begin with a headache, chills and a cough.

Muscle aches, fatigue, loss of appetite, a runny nose, watery eyes and a sore throat follow. Nausea, vomiting and diarrhea are also possible.

In addition to seniors, those most likely to become seriously ill from the flu include people with chronic medical conditions, young children, pregnant women and indigenous Canadians, according to the agency.

Recovery in most people will typically take between seven and 10 days.

Canadians can also guard against illness through frequent hand washing, keeping common surfaces clean, staying home when sick and keeping their hands away from their faces.