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Their announcement followed on the heels of news from two rivals in the global coronavirus vaccine race — Pfizer and Moderna — that their products appeared to be 95 per cent effective in phase-three trials.
The promising results are better than expected. But all require two doses, with a gap of 21 days for Pfizer’s product and 28 days for the other two.
It has to be done
In fact, of the seven vaccines in late-stage trials that the federal government has pre-ordered, only one, developed by Johnson & Johnson, needs just a single injection. It has yet to report any phase 3 results.
Adherence to multi-dose vaccinations is relatively good for young children, who typically have regular medical appointments and are guided by their parents, noted Wilson.
The research around adult vaccination is more sparse but the findings have a consistent theme, the word “suboptimal” appearing in many of the papers.
A 2009 U.S. study, for instance, found that only 40-50 per cent of people completed two-dose hepatitis A and varicella (chicken pox) vaccinations, the numbers falling even lower for teenagers and young adults.
A U.K. study published last year found that a mere 11 per cent of adults got the required two doses of Hepatitis A vaccine within one year, the number rising to just 23 per cent by 36 months. A similar U.S. study in 2018 suggested only 32 per cent of adults had obtained their second Hepatitis A injection within 42 months.
People have told researchers they didn’t know an additional shot was needed, couldn’t fit it into their schedule or needed a reminder, said Houle, who helped conduct a similar study using Alberta data..
