COVID-19 Vaccine Third Dose Eligibility Expanding to Individuals aged 70 and Over and Other Population Groups


The Eastern Ontario Heath Unit (EOHU) is pleased to inform the public that adults 70 years of age and older become eligible to receive a booster dose of an mRNA COVID-19 vaccine six months following their second dose as of November 3, 2021.

Third dose eligibility, six months following the second dose, is also expanded to:

  • Indigenous populations on or off reserve and their household members aged 18 and over
  • Health care workers, as defined by the Ministry (Appendix B)
  • Designated essential caregivers in congregate settings
  • Individuals who received 2 doses of AstraZeneca or 1 dose of Janssen
    • Recommended to receive an mRNA vaccine for third dose unless contraindicated

Two Doses Remain Effective

Receiving a third dose is recommended however is not urgent and not mandatory. A third dose will help to provide individuals in these groups with an improved immune response to prevent infection. Evidence continues to show that two doses of an mRNA COVID-19 vaccine provide strong protection against severe illness, hospitalization and death. Individuals are still considered fully vaccinated with two doses.

Waning of Protection

Certain populations were prioritized early in Ontario’s COVID-19 immunization program, leaving more time for waning, should it occur. As well, many received their vaccines using the manufacturers’ recommended interval. Evidence to date suggests that, compared to longer intervals, shorter intervals between first and second doses result in lower immune responses and therefore may also result in more rapid waning of protection.

Evidence shows that several months after receiving two mRNA COVID-19 vaccine doses, the immune response in the elderly population wanes compared to the general population. Emerging data also indicates that protection from infection decreases more quickly in individuals who received 2 doses of AstraZeneca or 1 dose of Janssen.

Since August 2021, Ontario has been offering third doses of a COVID-19 vaccine to certain vulnerable populations who have a decreased immune response after COVID-19 vaccines compared to the general population. The EOHU has completed third dose vaccination for residents of long-term care and retirement homes.

Accessing a Third Dose

On Saturday November 6 at 8:00 a.m., Ontario’s COVID-19 vaccination portal will begin to accept vaccine bookings for individuals eligible for a third dose. Booking will be available at Clinics will be added into the system regularly, please continue to check back. Individuals who require assistance with booking can call the Provincial Vaccine Contact Centre at 1-833-943-3900. If you need assistance or special accommodations, you may also call the EOHU at 1-800-267-7120. Clients needing a first or second dose can also use Ontario’s vaccine booking system.

As of November 3 and moving forward, walk-in clients for third doses will be accepted, however, clients are encouraged to book an appointment once Ontario’s COVID-19 vaccination portal becomes available on November 6. We continue to welcome individuals needing a first or second dose with or without an appointment.

If you, or someone you care for, meet the criteria for a third dose, we encourage you to seek vaccination at a partnering pharmacy or your health care provider. COVID-19 vaccines may be given at the same time as, or any time before or after, the flu shot or other vaccines. Either mRNA COVID-19 vaccine (Pfizer-BioNTech or Moderna) may be used as a booster dose, regardless of which COVID-19 vaccine was used in the primary series.

Continued Collaboration

While the COVID-19 vaccine is highly effective, the province is planning to expand eligibility for a booster dose to all Ontarians over time. If you, or the individual seeking a third dose, do not fall within one of the eligible groups for a third dose, or you have not reached the minimum interval since your second, please do NOT try to schedule an appointment or walk-in. Clients seeking a third dose will be asked to provide proof of eligibility before receiving their vaccine. We are requesting everyone’s collaboration and patience as we continue this enormous vaccination effort.

For the latest updates about which population groups are eligible to receive a third dose of the vaccine and how to access it, please regularly visit the Eastern Ontario Health Unit’s website at