Early results show flu vaccine more than 50% effective: BCCDC

The BC Centre for Disease Control says early evaluation shows this year’s influenza vaccine formula is providing “substantial” protection against the wave of flu so far.

“The earlier-than-usual influenza epidemic this season has enabled us to assess vaccine effectiveness earlier than usual,” BC CDC epidemiologist and Canadian Sentinel Practitioner Surveillance Network lead Dr. Danuta Skowronski said.

“We will update our analyses in the new year, but these interim findings show a substantial reduction in the risk of influenza illness for vaccinated people who seek medical care.”

Analysis for the period from Nov. 1 to Dec. 14 with samples from B.C., Alberta, Ontario and Quebec had cut the risk of medically attended influenza-like illness by more than half, with an estimated vaccine effectiveness of 55 per cent.

An update from the BCCDC on Thursday also showed there had been no additional flu-related deaths among children and youth this season. Six people under the age of 18 have died so far this year, several due to suspected influenza-linked bacterial infections.

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That same update showed that the epidemic wave appears to be waning. About 16 per cent of samples over the week ending Dec. 17 came back positive — down from a high of 27 per cent during the week ending Nov. 26.

Respiratory syncytial virus (RSV), however, continues to gain ground.

The BCCDC’s latest analysis shows the number of tests that came back positive for RSV for the week ending Dec. 17 jumped to 13 per cent, up from six per cent in the week ending Nov. 26.

Test-positivity for both RSV (37 per cent) and influenza A (21 per cent) remains higher among children and youth younger than 18 than in the general population, the BCCDC said.

According to the BCCDC, the H3 subtype of influenza A remains the dominant strain of influenza this year, accounting for more than 90 per cent of tested samples. The H3N2 subtype is often linked to more severe outbreaks and lower vaccine effectiveness, however, this year’s vaccine appears to be as good as or better than in previous years the subtype was dominant, the agency said.

“Vaccine protection is especially important for people at higher risk of severe complications and for a health-care system that is managing the circulation of multiple respiratory viruses at the same time as we enter the holiday period,” Skowronski said.

The province continues to recommend vaccines for anyone aged six months and older, and is urging anyone who feels unwell to stay home.