British Columbia is enduring a double whammy this flu season, combining a particularly tricky H3N2 influenza with a nasty outbreak of respiratory syncytial virus (RSV), according to the BC Centre for Disease Control.

Late November and early December saw a substantial spike in RSV cases, while H3N2 was still holding steady before the holiday season, based on samples submitted to B.C.'s public health laboratory.

"RSV is sometimes as dangerous as influenza in the elderly and the very young and we are seeing (both in circulation)," said Danuta Skowronski, epidemiology lead for influenza and emerging respiratory pathogens for BCCDC. "That's one of the reasons we are seeing heightened outbreaks of respiratory illness in the community right now. They are both competing for airspace, so to speak."

RSV is very common and typically causes mild cold-like symptoms, but it can be a serious health threat to infants and people with weak immune systems.

"Care facility outbreaks of RSV can be as dangerous as influenza for the elderly, who don't handle respiratory viruses very well," she said. "We are dealing with a double whammy."

Flu infections have been sporadic through the fall with care homes being the hardest hit, but new infections are now picking up substantially.

The holiday season — with so many extra opportunities for socializing between people in different age groups — tends to amplify the spread of influenza, said Skowronski.

Flu outbreaks appear to be peaking this week in Alberta, Ontario — where it sent hospital admissions are soaring — and Quebec, where record numbers of children are arriving at hospitals with flu symptoms.

Ontario's statistics — updated to Dec. 20 — show the number of flu cases confirmed by lab tests to be similar or lower than in recent years. However, reports from hospitals and others suggest the numbers have been spiking over the last week or so, said Doug Sider, Public Health Ontario's head of communicable disease prevention.

Public Health Agency of Canada statistics, which typically lag behind provincial numbers, show close to 2,000 confirmed cases nationally by Dec. 13, compared to less than 400 last year. The year before that, however, the agency had recorded about 1,400 cases by that date.

"Typically we see influenza peak in late January and February, so we are seeing a fairly early spike elsewhere," Skowronski said. "We are lagging behind other provinces, but I don't think we are going to be exempt from this."

Complicating this year's flu season is a "substantial" mismatch between the vaccine developed for this season and the fast-changing H3N2 flu strain that has taken hold across the country.

Mutations in the flu virus lead to some level of mismatch every few years — mostly recently in 2012 — reducing the effectiveness of the vaccine, which is formulated well before flu season starts.

"It's a new variant circulating and not the one in the vaccine, but H3N2 is already known to most people's immune systems, so most people will recover completely without medical treatment," Skowronski said. "You will just feel like you've been hit by a truck, totally depleted and achy."

Healthy young people should avoid going to the hospital with flu, which raises the risk the virus will spread people who are frail and vulnerable to medical complications

People who have serious chronic medical conditions should consult with their doctor and have a plan in place should they contract the virus, she said.

The antiviral drug Tamiflu can shorten and reduce the severity of influenza, but it works best when it is taken within 12 hours of the onset of illness.

rshore@vancouversun.com

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