MEDICAL ADVISORY: COVID-19 Vaccines and Interval Recommendations

Issued by:  M. Mustafa Hirji, MD, MPH, FRCPC, Medical Officer of Health & Commissioner (Acting)

COVID-19 Vaccine Extended Interval for Second Dose

• The National Advisory Committee on Immunization (NACI) has recommended extending the interval for the second dose of COVID-19 vaccine up to four months for all Health Canada approved COVID-19 vaccines
• The Ministry of Health’s Guidance on the Extension of the Second Dose Interval incorporates this recommendation with limited exceptions
• The decision to shift schedules was made after careful review of the science, including the experience of countries like the UK, which have been delaying second doses
• By delaying the second dose and vaccinating twice as many people with one dose, it was found that more infections, hospitalizations, and deaths from COVID-19 could be prevented

COVID-19 Vaccine Interval Recommendations

• NACI recommends that COVID-19 vaccines should not be given simultaneously with other vaccines (live or inactivated) to maximize benefits of COVID-19 vaccination while minimizing any risks of harm (e.g., potential immune interference or the erroneous attribution of an adverse event following immunization (AEFI) to a particular vaccine)
  • Except in a case where another vaccine is required for post-exposure prophylaxis
  • In the event a COVID-19 vaccine is inadvertently administered at the same time as another vaccine, neither dose should be repeated
• Individuals who receive a non-COVID-19 vaccine are recommended to wait at least 14 days before getting a COVID-19 vaccine
• After receiving an mRNA or viral vector COVID-19 vaccine, an interval of at least 28 days is recommended before receipt of a non-COVID-19 vaccine
• Refer to NACI Statement: Recommendations on the use of COVID-19 vaccines

Blood Products and Human Immunoglobulin Interval Recommendations

• COVID-19 vaccines should not be given simultaneously with monoclonal antibodies or convalescent plasma
• Administration of convalescent plasma or anti-SARS-CoV-2 monoclonal antibodies close to a COVID-19 vaccine may decrease effectiveness of a COVID-19 vaccine and/or anti-SARS-CoV-2 monoclonal antibodies
• There is insufficient evidence to guide timelines for receipt of both COVID-19 vaccine and any monoclonal antibodies or convalescent plasma for treatment or prevention of non-COVID-19 disease
• Timing of COVID-19 vaccine with the receipt of the above products should be determined by expert clinical opinion on a case-by-case basis

Tuberculin Skin Testing Intervals

• NACI updated their guidance regarding tuberculin skin tests (TST) and interferon gamma release assays (IGRA) to reflect COVID-19 vaccine administration
  • Although the COVID-19 mRNA or viral vector vaccines are not live vaccines, possible implications on TSTs and IGRAs has not been fully evaluated
  • Administering either mRNA or viral vector vaccines prior to TST or IGRA test may theoretically lead to a false-negative result due to their impact on cell-mediated immunity

TST and IGRA Testing Recommendations

If an individual requires a TST or an IGRA test, the following is recommended:

• Administer and read the test prior to immunization or delay test at least four weeks after vaccination
• COVID-19 vaccination may take place at any time after all steps of the TST have been completed

In situations where an opportunity to perform a TST or IGRA test might be missed:

• Testing should not be delayed
• Re-testing of individuals with negative results whom there is high suspicion of latent tuberculosis (TB) infection is recommended at least four weeks post COVID-19 vaccination to verify results
• Health care professionals are encouraged to weigh the risks and benefits of delaying TST or IGRA testing for each individual
• Refer to NACI’s Recommendations on the use of COVID-19 Vaccines

Reporting

• To report a tuberculin skin testing to Niagara Region Public Health, complete the online Tuberculosis Skin Test Report or fax the completed form to 905-682-6470
• For questions, please call the Infectious Disease program at 905-688-8248 or 1-888-505-6074 ext. 7543 Monday to Friday 8:30 a.m. to 4:30 p.m.

For further information on COVID-19 vaccines, refer to the Health Care Professionals Frequently Asked Questions webpage or call the COVID-19 Health Care Professionals Information Line at 905-688-8248 and press 7, then press 1. The COVID-19 Health Care Professionals Information Line is available Monday to Friday 9:15 a.m. to 4:15 p.m.