Several provinces are offering a new vaccine this year specially designed to provide better protection to seniors. But some infectious disease experts say the vaccine isn’t effective enough to justify public coverage, especially since it costs several times more than a regular flu shot.
Fluzone High-Dose, manufactured by Sanofi Pasteur, contains four times the amount of antigens compared to a regular flu shot and protects against three common flu strains. Approved for people 65 and older, the idea is that the higher dose will help seniors mount a better immune response and be better equipped to fight off the flu.
The shot, which first came on the market in 2016, is now covered for those 65 and older who live in long-term care homes in Saskatchewan, Manitoba, Ontario, Nova Scotia and Prince Edward Island. Ontario is the only province that has also extended coverage to people 65 and older who get it from a doctor or nurse practitioner.
But in B.C. and Quebec, health officials have declined to cover the new high-dose flu shot, citing the high cost of the vaccine and what experts there describe as lacklustre evidence Fluzone High-Dose is much better than the standard dose. Alberta, New Brunswick and Newfoundland are also not covering the new shot, although they did not say why.
The evidence for the high-dose shot “indicates only a small added benefit for seniors, compared to the substantially increased price,” Bonnie Henry, B.C.'s provincial health officer, wrote in an e-mail.
According to the research, about 200 seniors would have to be vaccinated with the high-dose shot to prevent one case of influenza, Dr. Henry wrote. About 4,000 seniors would have to be vaccinated with the new shot to prevent one flu-related hospitalization.
The divergent policies are part of a continuing debate over the targeted flu shot that experts say has major implications for future influenza vaccination programs – and the amount of money it costs to deliver them.
Seniors tend to be more vulnerable to complications from the flu because their immune systems may be weaker than those of younger people. Health Canada says 3,500 people die from the flu every year and 12,200 are hospitalized, with many of those affected being 65 and older.
Research also shows the regular flu shot may not be as effective in older age groups.
Health officials in the provinces where the high-dose shot is covered, as well as Sanofi Pasteur, declined to disclose the cost. But one infectious-disease expert says it is five times more expensive than a regular flu shot. Shelly McNeil, a vaccine researcher at Dalhousie University and deputy director of the Canadian Center for Vaccinology, said it costs $88 in Nova Scotia.
Danuta Skowronski, epidemiology lead of influenza and emerging respiratory pathogens at the BC Centre for Disease Control, said the benefits don’t justify the price.
She also said the new flu shot has only been studied for a few seasons and that there are unanswered questions health-policy officials should consider before they get locked into an expensive multiyear agreement. For instance, emerging research suggests people who get repeat flu shots every year may actually experience reduced immunity in subsequent years. That could have implications for seniors who receive a high dose of the flu shot, she said.
“Clearly, we need to know how the increase in cost compares to the increase in benefit," she said.
Quebec’s immunization committee, which provides recommendations to provincial health officials, wrote in a 2016 policy document there’s insufficient evidence for public coverage of Fluzone High-Dose. The document also raised concerns over the potential risks of exposing seniors to such high doses every year, considering that some evidence suggests this could reduce the immune response.
But other experts, such as Dr. McNeil, said there’s “clear evidence” the high-dose vaccine is superior.