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Ontario shortens interval between vaccines for AstraZeneca to eight weeks

Monday, June 14, 2021 @ 9:42 AM | By Amanda Jerome

The Ontario government announced on June 12 that people who received the AstraZeneca COVID-19 vaccine can get their second dose eight weeks after their first shot, instead of waiting the customary 12 weeks.

According to the government release, “with informed consent, individuals can choose between a second dose of AstraZeneca or an mRNA vaccine, at an eight to 12-week interval, recognizing that while waiting 12 weeks helps to ultimately provide more protection, some may choose to receive their second dose sooner to have the increased protection provided by a second dose earlier.”

The release explained that 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).”

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. There is evidence that a longer interval between two doses of the AstraZeneca vaccine (such as a 12-week interval) provides higher protection,” the release added.

As of June 14, individuals who received AstraZeneca as their first dose will be able to book their accelerated second shot.

“Individuals who wish to receive an mRNA vaccine for their second dose can book an appointment through the provincial booking system, through public health units that use their own booking system, or a participating pharmacy. For individuals who wish to receive second dose of the AstraZeneca vaccine, individuals can contact the pharmacy or primary care provider where they received their first dose,” the government release noted.

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