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Should I be worried about waiting up to four months for my second dose?

Studies have shown that the first dose of a COVID-19 vaccine can be at least 70% to 80% effective against the virus. This is still very strong protection against COVID-19.

→ UPDATE: Manitoba has resumed offering second doses as of May 21, and you can learn more about who is eligible to book their second dose here

No concerns have been identified that delaying the second dose will decrease protection after getting that second dose. In fact, with many vaccines a delay between the first and second doses is required to get the best protection.

By deferring the second dose for up to four months, physicians and health providers have been able to immunize more people sooner with a first dose.  

In other words, this means instead of one person getting 95% protection from two doses, two people can get at least 70-80% protection now, and then both will get their second dose later. 

While the maximum recommended time, or interval, between doses at this point is 16 weeks (4 months), it’s also important to ensure you wait at least the minimum recommended time:

  • Pfizer: at least 28 days (4 weeks)
  • Moderna: at least 28 days (4 weeks)
  • AstraZeneca: at least 28 days (4 weeks) is the minimum but generally it is recommended to wait 8-12 weeks for best protection. 

You can learn more from:

Delayed Second Dose versus Standard Regimen for Covid-19 Vaccination (New England Journal of Medicine)
Public health statement on deferral of second dose (B.C. Centre for Disease Control)