This is a news statement from the Public Health
Agency of Canada:
Flu vaccine manufacturers
have reported problems growing one of the strains recommended for this
flu shot. As a result, the vaccine should be available to the provinces
at the end of October or beginning of November.
This is about a month later than usual in some jurisdictions and means
that the timeframe for the delivery of public programs will be compressed.
People, however, should be able to receive the vaccine before the peak
of the flu season, which typically does not occur until mid-December
The production of influenza vaccine is a unique and complex process.
The vaccine must be produced annually to ensure it provides the best
possible protection against the latest types of flu virus in circulation
since new viruses emerge each year.
The makeup of the vaccine is based on annual recommendations from
the World Health Organization which are usually received in mid-February.
Production starts soon after and usually takes about six months. Vaccine
manufacturing is a biological process where manufacturers are dealing
with a live, unpredictable virus. This means that there is always some
potential for variation in the process. Time lines for the manufacturing
and testing of the vaccine are also tight so challenges in the production
process may result in unexpected delays.
Based on the World Health Organization guidelines, Canada's National
Advisory Committee on Immunization recommended this year's influenza
vaccine contain an A/New Caledonia-like, an A/Wisconsin-like and a
B/Malaysia-like virus strains.
There was a delay in getting the appropriate seed strain for the A/Wisconsin
strain. The strain also had a low yield so it took longer to produce.
The WHO also issues test kits that are used to determine the content
and strength of the vaccine. Given the problems with the A/Wisconsin
strain, the distribution of the test kits were also delayed. All of
these factors have led to the end of October delivery date.
The ideal time to be vaccinated is anywhere from October to November.
Obviously, federal, provincial and territorial health authorities would
prefer to see public programs launched as early as possible but this
is a situation that all manufacturers are facing. The Public Health
Agency is working closely with the provinces and territories to develop
a plan to manage the supply of the vaccine and make sure it is available
when and where it is needed.