A second study from Quebec is calling into question the timing at which young children are vaccinated against measles.
The new research shows that teenagers who received the recommended two doses of measles vaccine but who got the first shot when they were 12 months old were six times more likely to go on to contract the disease than those who got their first dose at 15 months.
The work was done to try to puzzle out why a number of teenagers who would have been assumed to have been protected — because they got two doses of vaccine in childhood — nevertheless were infected during Quebec’s large measles outbreak in 2011.
More than 700 measles cases were reported in that outbreak.
Lead author Dr. Gaston De Serres of Quebec’s provincial public health agency presented the work Sunday at a major international infectious diseases conference in San Francisco. The study was a followup to an initial paper on the outbreak that he presented to the same conference last year.
While the situation bears watching, De Serres said Canadian policy on timing of measles vaccine delivery isn’t likely to change just yet.
“For Canada I would probably say that at this time we will not change the schedule,” De Serres said during a webcast press conference from ICAAC, the Interscience Conference on Antimicrobial Agents and Chemotherapy.
“We need to follow up with more studies.”
Prior to the introduction of the measles vaccine, most children contracted the disease and roughly two million a year died from it.