Mixing Vaccines for Better Immunity


Canadian health officials are reviewing the research on mixing various COVID-19 vaccines for better immunity. Some scientists believe two doses of different products could boost a person’s immune response. The United Kingdom is already studying a mixed vaccine regimen.
The National Advisory Committee on Immunization (NACI) caused some confusion. After hundreds of thousands of Canadians received the vaccine already, NACI said the viral vector shot from AstraZeneca is not the preferred option. The reason being its association with vaccine-induced immune thrombotic thrombocytopenia (VITT). It is a condition causing blood clots.

VITT frequency in individuals who received the AstraZeneca shots range from 1 case in 26,000 to 1 case in 127,000 administered cases. The Ontario Science Table published the figures. Some provinces are considering pausing AstraZeneca vaccinations altogether. Moreover, Manitoba’s chief provincial public health officer, Dr. Brent Roussin, said they discuss a temporary suspension at their provincial program.

Mixing Vaccines

Christine Elliott, Ontario’s health minister, said Monday that recipients of the AstraZeneca vaccine might receive a different shot for their second dose. However, Health Canada regulators have deemed the vaccine to be safe and effective. Despite this, many people are now looking at their options for their second dose.

Currently, the COVID-19 Heterologous Prime Boost study or “Com-COV” is collecting data to determine whether receiving two different types of vaccine boosts a better immune response. Both Canada and the United Kingdom are now following a two-dose schedule at the moment. The primes dose and a second boost dose some weeks later. On the other hand, the Oxford researchers are evaluating the effects of vaccine combinations. In fact, they are mixing AstraZeneca and Pfizer. A second study, Com-COV 2, includes the products from Moderna and Novavax as booster vaccines.

The deputy chief medical officer for England, Jonathan Van-Tam, said “this research will “give us greater insight into how we can use vaccines to stay on top of this nasty disease.”