H1N1 predominant, with more severe presentations among children and non-elderly adults.

This is an update on the 2018/19 influenza season. We are currently in the midst of the 4-6 week peak of influenza activity.

We have been seeing typical levels of influenza activity in terms of influenza-like illness presentations to GP clinics based on MSP and sentinel surveillance data. However, visits to the Children’s Hospital Emergency Department are higher than expected. Clinicians have also noted more severe presentations of influenza among children and non-elderly adults within our region.

Among influenza positive specimens tested at the lab, the predominantly circulating strain is influenza type A H1N1. H1N1 is known to impact children and non-elderly adults disproportionately. In keeping with this, to date, approximately 75% of all influenza H1N1 detections across the province were among patients under the age of 65. Similarly, only five influenza outbreaks have occurred in long term care settings this season which is much lower than last year.

Given that children and non-elderly adults are being disproportionately impacted by H1N1 this season, please:

  1. Keep influenza on the differential and consider influenza antiviral treatment for patients presenting with influenza-like illness, particularly children and non-elderly adults. There are reports of these groups experiencing more severe presentations of influenza with complications this season.

  2. Continue to promote influenza vaccination: Children and non-elderly adults are often less likely to get vaccinated than seniors, but should consider immunization given circulating H1N1. Vaccine effectiveness is typically higher for H1N1 and given that we are in the midst of peak influenza activity with circulating influenza levels expected to be high for the next several weeks, the vaccine can continue to provide protection against H1N1 and influenza B, which is typically seen during the later stages of the season.

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