Ontario shortens 2nd dose timeline for AstraZeneca COVID-19 vaccine to 8 weeks
Posted June 12, 2021 3:20 pm.
Last Updated June 12, 2021 4:18 pm.
The Ontario government is allowing individuals who received their first dose of the AstraZeneca COVID-19 vaccine to get their second dose in eight weeks rather than 12 weeks.
Those who got AstraZeneca as a first dose can will have the option of getting a second dose of the same vaccine or an mRNA vaccine, either Pfizer or Moderna.
With informed consent and recognizing that 12 weeks will ultimately provide more protection, the province is letting individuals choose when to receive their second dose between eight and 12 weeks.
The province says AstraZeneca recipients will be eligible to book their second shots as of Monday at 8 a.m., noting those who want a second dose of the same vaccine must revisit the place where they received the first one. Residents who wish to switch to the Pfizer-BioNTech or Moderna vaccines as a second shot may book through the provincial portal.
“This decision is based on emerging clinical evidence about the administration of two doses of different vaccines, as supported by the National Advisory Committee on Immunization (NACI),” the province said in a statement.
“Evidence from multiple studies indicates that mixing of COVID-19 vaccines (receiving an mRNA vaccine after an AstraZeneca vaccine) at dosing intervals between eight and 12 weeks is safe and demonstrates a beneficial immune response.”
The province noted, however, that some evidence suggest waiting for a longer interval between AstraZeneca doses “provides higher protection.”
The province had been facing growing pressure to shorten the interval, with mayors in one long-standing COVID-19 hot spot region saying residents should have the choice to seek full immunity sooner and acquire better protection against more infectious virus variants.
