Images of long lines of people waiting for H1N1 shots after the highly publicized death of a 13-year-old boy just before the vaccination program began contributed to a loss of public confidence in the system, doctors say. (Victoria Foley/CBC)

Canada's health-care system didn't fully address the risks posed by the H1N1 pandemic on vulnerable populations such as pregnant women and aboriginal people, doctors say.

Monday's issue of the Canadian Medical Association Journal includes two papers on H1N1.

The first assesses Canada's response to the pandemic and outlines important lessons that may help in preparing for future flu outbreaks.

"However reasonable the initial precautionary decision to order 60 million doses of adjuvant vaccine was, subsequent decisions and problems resulted in the wheels falling off the immunization cart," wrote Dr. Don Low of the microbiology department at Toronto's Mount Sinai Hospital and Dr. Allison McGeer, also of Mount Sinai and the University of Toronto.

"The vaccine could not be made quickly enough to protect Canadians from the second wave, the complexity of delivering vaccine was badly underestimated and attempts to deliver rapid public education about vaccination with an adjuvant vaccine failed."

Adjuvants are additives that boost the immune system's response to a vaccine.

The analysis showed the death rate was lower than initially projected, but the years of life lost and hospitalizations were substantial because the 2009 pandemic skewed toward younger ages than deaths from seasonal flu.

Last year, more than three-quarters of cases occurred among people younger than 30 years of age, with a peak among those 10 to 19, Low and McGeer said.

Among certain groups, including indigenous populations of North America and the Australian-Pacific region, rates of severe infection with swine flu increased by a factor of five to seven, the pair said.

Factors that may have contributed to the higher rates include:

• Crowding.
• Increased prevalence of underlying medical disorders.
• Alcoholism and smoking.
• Delayed seeking of or access to care and possibly unidentified genetic factors.

The Public Health Agency of Canada bought 50 million doses of H1N1 vaccine to vaccinate every Canadian who wished it.

But several factors complicated efforts to vaccinate Canadians:

• The vaccine manufacturer, GlaxoSmithKline, also had to produce nonadjuvant vaccine for pregnant women and children under three years of age.
• Televised footage of long lines of people waiting to be vaccinated following the highly publicized death of a 13-year-old boy just before the vaccination program began contributed to a loss of public confidence in the system.
• By the time vaccination clinics were running smoothly, the number of new cases was decreasing.
• Provincial health authorities made different decisions about priority groups for the vaccine.

A second paper in the same issue of CMAJ suggests a third wave of H1N1 is unlikely this year.

Prioritize older adults this season

The analysis of H1N1 antibodies after the pandemic showed 30 per cent of people tested who were 50 to 79 had protective antibodies against the virus, based on blood tests of 1,127 people in British Columbia's Lower Mainland.

After the waves of infection and the immunization campaign last fall, Dr. Danuta Skowronski of the BC Centre for Disease Control and University of British Columbia in Vancouver and her co- authors found a 70 per cent protection rate in people under age 20.

But antibody protection rates in adults aged 20 to 49 were lower, 44 per cent, and 50 to 79 years of age at 30 per cent.

People 70-79 had the lowest rate of antibodies at 21 per cent, whereas those over 80 years had higher rates.

"Our findings support a shift from the prioritized immunization of the young that occurred in fall 2009 to prioritized immunization of older adults for the coming 2010-11 influenza season to protect against severe outcomes due to both pandemic and seasonal influenza," the study's authors concluded.

The B.C. study was funded by the Michael Smith Foundation for Health Research.

Authors of both papers reported potential conflicts of interest such as participating in advisory boards for pharmaceutical companies.