January 19, 2001

Influenza Immunization: Ontario
Ontario's decision to make the influenza vaccine available at no charge to all its citizens for this year's flu season has sparked debate in the public health community. The "pro" side argues that at best, this strategy will be a major advance in influenza control; at worst, it will reduce the burden of influenza but will not be efficient, at which point it can be modified appropriately. The potential additional benefits include protecting vulnerable populations, improving high-risk coverage, reducing community transmission and improving preparedness for a pandemic. The "con" side argues that given the cost of the Ontario program ($38 million) and the quality of information available, it is unlikely universal vaccination will be introduced elsewhere. As clearly stated by the Ontario government, the aim is to ease pressure on emergency services during the influenza season. There is absolutely no evidence that universal vaccination has ever achieved such a goal.
Source: Canadian Medical Association Journal, Vol 164, No 1, January 9, 2001

Meningococcal Disease: Quebec
A gradual increase in the number of cases of meningococcal disease (MCD) reported to the public health authorities was observed in Quebec in the late 1980s. In an attempt to contain this outbreak, Quebec decided to immunize 1.9 million children between the ages of 6 months and 20 years. The program actually managed to reach 84% of that cohort. The program, which ran from December 1992 to March 1993, provided a perfect opportunity to study the effectiveness of the vaccine and such a program. Researchers studied the incidence of the disease in the province over the following 5 years, comparing rates among those who had been immunized versus those who had not. The incidence of serogroup C disease decreased after the mass immunization campaign, from 1.4 per 100,000 in 1990-1992 to 0.3 per 100,000 in 1993-1998, and the overall incidence of other serogroups remained stable at 0.7 per 100,000. Vaccine effectiveness was strongly related to age at vaccination: 83% for ages 15-20 years, 75% for ages 10-14 years, and 41% for ages 2-9 years. The researchers concluded that serogroup C polysaccharide vaccine is effective for controlling outbreaks in teenaged individuals but should not be used in children < 2 years of age. Ultimately, cost-effectiveness should be the criterion for deciding which of the polysaccharide or conjugate vaccines should be recommended for different age groups. Results of randomized trials and epidemiologic studies on conjugate vaccines are urgently needed for comparison purposes.
Source: Journal of the American Medical Association, Vol 285, No 2, January 10, 2001

Poliomyelitis: Dominican Republic and Haiti
The Pan American Health Organization has been monitoring an outbreak of poliomyelitis in Haiti and the Dominican Republic and has concluded that the situation appears to be under control and has urged countries not to retreat from achieving and maintaining high vaccination coverage. One case of poliomyelitis due to a Polio Type 1 vaccine-derived virus was confirmed in Haiti in August 2000. Subsequent intensive case searches throughout the country were conducted during October, November and December 2000, and 14 suspected cases were investigated epidemiologically, clinically and by the laboratory. So far, results have been completed for 6 of these cases, all negative for poliomyelitis. Results for the other 8 cases are expected within upcoming weeks. In the Dominican Republic, there have been 6 poliomyelitis cases due to a vaccine-derived poliovirus Type 1. Intensive investigation over the last few weeks did not uncover additional cases. Two weeks ago the government there vaccinated 1.2 million children during a national campaign. The Pan American Health Organization sent 16 epidemiologists to support the health ministries in the Dominican Republic and Haiti. The outbreak caused serious concern because the Western Hemisphere has been free of wild poliovirus circulation since 1991, and because the virus identified is an unusual derivative of the Sabin type 1 oral poliovirus vaccine (OPV).
Source: Pan American Health Organization, Press Release, January 8, 2001

The details given are for information only and may be very provisional. Where incidents are considered of national importance and are ongoing, the initial report will be updated as new information becomes available.