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Extension of Second Dose Intervals for COVID- 19 Vaccines

Ontario government is extending the vaccination dose interval up to 16 weeks for the three two-dose vaccines currently approved by Health Canada (Pfizer-BioNTech, Moderna and AstraZeneca/COVISHIELD). This is based on the recommendation of the National Advisory Committee on Immunization (NACI). Individuals who have already booked their second dose will have their appointments rescheduled. This will...


COVID-19 Vaccines

Dear community members and families, In the last few weeks, we have seen significant movement in our understanding of the COVID-19 vaccines. As of today, here is what we know: The vaccines are safe The vaccines approved for use in Canada work by sending a message to our body’s immune system to stimulate our natural immune response....


3 Approved COVID-19 Vaccines Efficacy

Interim results of two large randomized, placebo-controlled trials (RCTs) demonstrate ~95% relative efficacy in preventing COVID-19 (Pfizer, Moderna). The AstraZeneca/Oxford vaccine has ~70% relative efficacy. Absolute benefits will vary with baseline risk and time but if annual risk of developing COVID-19 is 20%, then vaccine would decrease risk to 1% (6% with AstraZeneca/Oxford). These vaccines...