Pfizer and Moderna vaccines - stronger together?
Canadians who are offered a different vaccine for their second COVID-19 vaccination than for their first should not be afraid to combine them. What are the concerns?
Recently, it has become increasingly common to hear Canadians refuse to get the Moderna vaccine directly at clinics if they have already received a Pfizer injection during the first stage. People fear that mixing two different injections may be harmful to their health or simply ineffective.
As you know, Pfizer is delivering 2.4 million vaccines each week to Canada to protect the population from the coronavirus pandemic. But this week, deliveries have been delayed, so health care providers in some provinces have changed their assignments, replacing vaccinated people with Pfizer vaccine with Moderna in the second phase of vaccination.
This action was taken after Canada's National Advisory Committee on Immunization (NACI) updated the vaccine guidelines. The committee found Pfizer and Moderna vaccines to be interchangeable because they are made with similar technologies — these drugs are very similar in their effects on the human immune system, so they are good at cross-reacting. Therefore, according to doctors, there should be no doubt about the effectiveness of the two different vaccines or their safety: by functioning together, Pfizer and Moderna can help Canada end the pandemic.
Experts and health professionals are urging people to get vaccinated with interchangeable vaccines, because not getting a second vaccination is dangerous and could jeopardize the fight against the pandemic that Canada has successfully fought in recent months. Cases of COVID-19 infection in the country have dropped by 80%, and hospitalizations and deaths have plummeted. Today, more than 66% of Canadians have been vaccinated with at least one dose of the antiviral vaccine and this cannot be stopped.
In light of the situation, health officials are sounding the alarm and urging people not to expect a Pfizer shipment next week, as the vaccination schedule could be completely disrupted due to widespread cancellations. Canadian health officials say vaccinations are the country's only long-term protection against the virus. Alison Kelvin, an assistant professor at Dalhousie University and a virologist at the Canadian Centre for Vaccinology in Halifax, said "Canada needs to continue to vaccinate to avoid future problems."