By Don Lawrence

The worry and uncertainty we feel today surrounding the COVID-19 pandemic might be familiar to those who experienced the polio epidemic in the first half of the 20th century. The polio virus came without warning, no one knew the cause or how it was spread, and there was no known cure or vaccine. Wild theories flourished.

The first polio vaccines were produced by Connaught Laboratories, a once world-class medical research facility that got its start at the University of Toronto during a diphtheria outbreak in 1914. Connaught’s primary focus was on meeting Canadian needs in public health products, and the high standard it established was adopted by the World Health Organization (WHO) for all global producers. Connaught conducted crucial research that led to the creation of a typhus vaccine during the Second World War, and created the Salk vaccine, which was credited with eradicating smallpox in 1977.

Many people today who were young students in Canada during the late ‘50s and ‘60s might remember the day when a nurse arrived at their school, and fear and anxiety mounted while in the lineup for a smallpox shot. The vaccine, like the more-familiar flu shot, consisted of a live virus that was killed or weakened and then stimulated antibodies to fight the variola virus that caused smallpox. The dose was given by a “scary” bifurcated needle that caused a blister, then a scar on the upper arm, a visual sign of smallpox immunity which that generation still carries today.

In 1972, Connaught was sold to the Canada Development Corporation and then acquired by Francebased Institut Mérieux in 1989. No Canadian government has had the foresight to restore domestic vaccine manufacturing since then. Now Canada is part of a group competing with national interests to share COVID-19 vaccines made abroad. The two approved in Canada at the time of writing are Pfizer-BioNTech and Moderna, which manufacture our supply in western Europe. Both are mRNA vaccines and they require two shots.

According to Dr. Theresa Tam, Canada’s Chief Public Health Officer, the mRNA delivers an “instruction set” to the cells in your body to make proteins that look like the spike proteins studded on the outside of the coronavirus. Your immune system identifies these proteins as ones that are not usually found in your body and begins building an immune response to them by making antibodies. Once the proteins are produced, the mRNA breaks down and is cleared from your cells.

The desired outcome is herd immunity, which happens when a large proportion of the community is immune to a disease through vaccination or previous infection. Experts estimate that we will need greater than 70 percent of the population immune to really break the chain of transmission, but this is still unknown and more modelling including variants is needed Your waiting time to get a COVID-19 vaccination might depend on your age.

Dr. Tam says the best way to prioritize who should get a COVID-19 vaccine, after high-risk, highpriority individuals, is to go by age. For Ontario’s priority schedule see