COVID-19 vaccine policies explained

Following a worrisome wait for a renewed supply of COVID-19 vaccines, many Albertans now have the opportunity to receive their vaccine much sooner than expected.  Many are pleased at the accelerated timelines and are ready to roll up their sleeves, but some are anxious or confused about the evolving COVID-19 vaccine recommendations.

COVID-19 vaccine guidelines are receiving much more interest by media and the general public than vaccination recommendations usually do during non-pandemic times. While this is helpful in informing and educating the public, it can also create high levels of anxiety if communication is not complete or clear.

To date, Health Canada has approved four different COVID-19 vaccines for use. All are safe and effective, but each has a different efficacy reported in clinical trials conducted by the manufacturer.  How is the layperson to interpret this information?

The key is understanding that reported efficacies for the four vaccines cannot be compared directly. No head-to-head trials were done to enable this comparison.  Each manufacturer conducted trials using different definitions of COVID-19 disease, in different countries, at different times with different levels of variants in circulation and in populations with varying demographic characteristics (age, underlying diseases such as diabetes, hypertension or heart disease, etc.).

What we do know is that all four vaccines protect very well against hospitalization and death from COVID-19 infection.

The Pfizer BioNTech and Moderna vaccine trials were conducted earlier when fewer variants were in circulation while the Johnson & Johnson trial was conducted later and enrolled more people over the age of 60 and with comorbidities such as HIV, diabetes and hypertension. These differences can affect the reported efficacy and make it impossible to compare vaccines directly.

What we do know is that all four vaccines protect very well against hospitalization and death from COVID-19 infection and all vaccines surpass the standard set by the World Health Organization for preventing any disease including mild illness.

What we don’t know is whether the vaccines can protect against long-term symptoms after COVID-19 infection. Similarly, we do not know if any of the four vaccines reduce the risk of transmission to others or how long immunity from vaccination will last. 

Concerns have been expressed around the National Advisory Committee on Immunization (NACI) recommendations for extending the dosing interval to 4 months from the shorter timelines used in the trials for vaccines requiring 2 doses.

The committee analyzed real world data and found that there were sustained high-levels of protection at 2 months after the first dose for the Pfizer BioNTech and Moderna vaccines.  Noting that immunity wanes gradually and does not “fall off a cliff” at two months, and citing a clinical trial showing that delaying the second dose of the Oxford-AstraZeneca vaccine for 12 weeks or more provided better protection against symptomatic disease, NACI expresses confidence that it is safe and beneficial to extend the dosing interval to cover as many people as possible within the shortest time frame.

Eighty percent of the Canadian population over 16 years can receive one dose of a vaccine by June 2021 with the extended dosing interval.  This policy would minimize hospitalization and deaths which clearly comprise the worst outcomes for COVID-19 infection. Achieving immunity in a large proportion of the population will rapidly drive down numbers of COVID-19 cases and bring the end of the pandemic and a return to normal life within reach.

NACI is monitoring data being collected weekly on vaccine effectiveness and will adjust recommendations if concerns emerge around waning protection. Science is not static and understanding that evidence evolves and builds with time will help us in this time where studies related to COVID-19 are proceeding at breakneck speed.  We can be confident that recommendations will be refined or changed as new information comes forth and adds to the body of scientific evidence.

There are many uncertainties and nuances to COVID-19 vaccination policy, but this is clear:   all four Health Canada approved vaccines are safe and effective; all four vaccines are similar for outcomes we care most about – death and hospitalizations; getting any vaccine at the earliest opportunity makes the most sense.

To optimize vaccine uptake, government and public health officials need to build trust with the public through clear and transparent communication. Family doctors, public health nurses and other health care providers can put evolving information around vaccines into their patients’ personal health context and customize communication to address patients’ specific needs and allay their fears.  Trust and confidence will be as important to the success of this vaccine rollout as vaccine efficacy and safety. 

By Vamini Selvanandan© 2021. This work is licensed under a Creative Commons CC BY 4.0 license. This article was originally published in the Rocky Mountain Outlook on Thursday March 18, 2021. Photo credit: Thirdman on

Recommended further reading:

One thought on “COVID-19 vaccine policies explained

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: