Influenza Vaccines

The H1N1 flu virus emerged in April 2009 and surveillance of its spread shows that it is affecting more young and healthy people than the regular seasonal flu, which normally affects seniors and young children. People with underlying medical conditions and pregnant women may be at a greater risk for severe illness from H1N1. Since the WHO’s declaration of a pandemic in June 2009, the H1N1 flu virus is now the dominant influenza virus in circulation in the world and in Ontario. Public health officials anticipate that the pandemic H1N1 flu virus will continue to be the predominant strain circulating this fall. As of September 22, there have been 78 deaths due to Pandemic (H1N1) 2009 in Canada, 24 of which have been in Ontario.


Ontario Ministry of Health and Long-Term Care (MOHLTC) announcement on changes to the seasonal flu immunization campaign this fall

Yesterday, the Ontario MOHLTC announced the approach that will be taken in phasing the two flu vaccine programs in the fall, by targeting those most at risk from complications from either of the flu strains.

In October, the seasonal flu vaccine will be offered to Ontarians 65 years and over and residents of long-term care homes
H1N1 vaccine will be offered to the general population in November.
The universal seasonal influenza immunization program will be offered to all other residents six months of age and older in December/January.

The decision to take this approach is based on scientific analysis by the province’s top immunization experts. Some of the considerations that were used to come to this decision are as follows:
Evidence shows the H1N1 flu virus will be the main strain in circulation this fall in Ontario
Seniors are most at risk for complications from seasonal flu while younger people are more at risk for complications from H1N1 flu. Also, data shows that infection from pandemic H1N1 virus does not typically occur in persons over age 60, probably as a result of residual immunity from exposure to H1N1 prior to 1957.
Some studies in Canada show a potential association between prior seasonal flu vaccination and risk of getting an infection with the H1N1 virus
There is no scientific data that supports the safety and effectiveness of administering the seasonal flu vaccine and the H1N1 vaccine at the same time

Next Steps

Please work with the CHNs in your communities to think about how they will reach out to those 65 years and older during the first phase of the seasonal flu vaccination campaign in October. This may be very similar to the approach used by communities for the pneumococcal vaccination campaign carried out over the summer months, where those aged 65 years and older were also targeted. We will continue to provide you with further updates on the two influenza vaccination campaigns this fall as more information becomes available.