Ottawa Public Health has run out of a special, high-dose version of the flu shot designed for people aged 65 and older.
In its place, public health officials say older adults should receive the regular flu shot because it still provides protection against multiple viruses.
"They've always had the choice between the two vaccines and definitely we would recommend they get vaccinated and not wait [until] we get more stock of the high-dose vaccine," said Marie-Claude Turcotte, a program manager with Ottawa Public Health.
"The important thing is to get the vaccine as early as possible in the season … so that you can build your immunity."
While Ottawa Public Health is out of the high-dose shot, it may still be available in local clinics, Turcotte said. Pharmacies do not carry the high-dose vaccine.
This year older adults had the option of receiving a high-dose version of the vaccine, called Fluzone High-Dose, that manufacturer Sanofi Pasteur said has four times the amount of antigen than the regular flu shot.
Fluzone Quadrivalent or Flulaval Tetra, also known as the regular flu shot, protects against four strains of influenza and can be given to adults and children aged six months and older.
More expected soon
In an email to CBC, Sanofi Pasteur said it should have more doses of the high-potency flu shot available for Canada soon and that regulatory approval of a new batch of doses is already underway.
The shortage of high-potency vaccines is due to a supply delay — caused by both a production issue and a month-long delay identifying one of the flu strains — not because Ontario ordered too few vaccines, Ontario's Ministry of Health said.
"To date, the province has received approximately 82 per cent of its total order of high-dose influenza vaccine available to seniors 65 years of age and older," wrote spokesperson David Jensen.
The rest is expected by late November or early December, he said.
Ontario ordered 10 per cent more vaccines in total than last year, including 200,000 more doses of the high-potency vaccine.
More people at clinics so far
Ottawa Public Health said it's too early to know whether more people are receiving the flu shot this year than previous years; however, attendance at its community flu shot clinics is up 31 per cent from last year.
It administers free flu shots to anyone in the city and provides flu vaccines to clinics.
There is still an ample supply of regular flu vaccine doses in Ottawa, despite a shortage nearby in Gatineau, Que., and issues at at least one clinic.
Dr. Mbuyamba Bella-Lufu said his family clinic still has many high-dose shots left but ran out of the regular flu vaccine. Many of his patients are refugees and have large families who have tapped out his reserves.
The clinic has been waiting for three weeks for a resupply of regular flu shots, he said.
"This is the longest that I've ever experienced in my clinic here," said Bella-Lufu.
Turcotte was surprised to hear of the shortage and said normally Ottawa Public Health can provide additional flu vaccines to clinics within three business days.