Wave, January / February 2013
If you are one of the unfortunate Manitobans who have struggled through the flu this winter, take heart.
The high fever, sore throat and full body ache have not necessarily been in vain.
In fact, information about your illness may very well help build a better flu vaccine, one that may be more effective in keeping the influenza virus at bay in the future, according to Dr. Salah Mahmud, Medical Officer of Health with the Winnipeg Health Region.
That's because the Region, along with Manitoba Health, is part of STRIVE - Surveillance Team Research on Influenza Vaccine Effectiveness - a major national influenza effort that aims to keep tabs on the flu as it circulates through Canada.
STRIVE counts influenza cases in British Columbia, Alberta, Manitoba, Ontario and Quebec, and looks at how effective the current vaccine is against the flu strains in circulation.
As Mahmud explains, the information gathered by STRIVE can be used to help better predict what kind of virus may circulate next year, and help health-care officials better respond to influenza outbreaks.
In Winnipeg, the detective work is done by the Region's Population and Public Health surveillance team, which tracks 45 different diseases and other trends daily, including influenza, tuberculosis and injuries.
Currently, the surveillance team, in collaboration with Cadham Provincial Laboratory, is tracking 15 different respiratory viruses, including the Respiratory Syncytial Virus, which mostly affects young children. The team issues weekly flu reports, noting how many case of influenza A and B are in the Region, along with how many people are reporting to hospitals with flu-like illnesses. They also work with the hospitals' Emergency, ICU and other departments, along with physicians in the community.
"There are 25 sentinel clinicians in Manitoba who, when a patient arrives with an influenza-like illness, will ask them if they are willing to take part in the study," says Mahmud, adding that this is the second year the Region has participated in STRIVE. "If they agree, the clinician collects a sample to be tested for influenza, and also asks whether the person had the influenza vaccine."
The purpose is to look at how influenza is hitting the average person. Mahmud says hospitals tend to treat the more severe cases of influenza. "They're mostly counting seniors and young children, so the numbers coming from the clinicians give us a more balanced look at influenza among the population as a whole."
The data being gathered through STRIVE is critical to containing the flu virus, says Mahmud. The influenza virus changes or mutates from year to year, with new strains popping up around the world. These are tabulated by the World Health Organization, which issues the best estimate for the top three strains due to arrive in North America during the winter months when influenza is common.
In the past, it often took two to three years for data on vaccine effectiveness in any given flu season to be available to scientists and health-care providers. STRIVE has helped by painting a picture of how influenza affects the population as a whole, by doing testing among average-risk people. It also provides health officials quicker access to information about emerging outbreaks, allowing them to take various actions, such as allotting more hospital beds for influenza patients and stocking anti-viral medication.
According to data gathered by STRIVE and other surveillance efforts in Canada, the dominant influenza virus this year is H3N2. As it turns out, this year's vaccine is a good match for the virus, says Mahmud, who has a PhD in epidemiology and is an assistant professor at the University of Manitoba in the Department of Community Health Sciences. "The vaccine is showing to be about 50 per cent effective against a person getting influenza," he says. On average, flu vaccines are 50 to 70 per cent effective against the viruses in circulation in any given year, adds Mahmud.
The best way to avoid the flu continues to be the flu vaccine. "Imagine landing in a busy Emergency Department with a bad case of the flu, and waiting for a bed to be freed," says Mahmud, adding that even healthy people can transmit the virus to those more at risk - children, the elderly and those with chronic diseases or other major health issues. "Reducing your risk by 50 per cent is nothing to sneeze at."
The ultimate goal of STRIVE and the Region's surveillance team is to play a part in helping scientists improve the effectiveness of the vaccine. "There is a lot of work being done to improve the vaccine, to come up with a universal vaccine that you would only have to take once in your life," says Mahmud.
Susie Strachan is a communications advisor with the Winnipeg Health Region.
WRHA flu surveillance reports: