TORONTO -- Ontarians who have yet to roll up their sleeve for the COVID-19 vaccine are a greater risk for serious illness and pose more of concern than breakthrough cases of people fully vaccinated, provincially driven research shows.

“I don’t think we need to be very concerned at all with breakthrough cases,” said Dr. Jeff Kwong, a senior scientist at ICES, an organization that researches infectious diseases including COVID-19 and the performance of vaccines.

Public Health Ontario reports between Dec. 14, 2020 and July 10, 2021, there has been 1,765 breakthrough cases, 898 of which were symptomatic and 867 were asymptomatic.

“The main job is to prevent the severe outcome, so if they are preventing hospitalization and deaths then they are doing their job. If they can prevent infection, that’s great as well. We know they don’t work as well as preventing infection as they do against hospitalization,” he said.

“One vaccine person may get the infection and it’s possible they may spread to another vaccinated person, but they are both protected from getting hospitalized, they are both relatively safe and it may seem like a cold.”

“What’s worrying me is there are people out there who are not vaccinated.”

Among long-term care home residents and health care workers between Dec. 14, 2020 and July 26, 2021 breakthrough cases made up 14.1 per cent of cases, partially vaccinated at 23.5 per cent. Not yet protected (meaning one shot received in the last 13 days) was 62.4 per cent.

That message was echoed by Ontario’s Medical Officer of Health.

“Since Dec. 14 2020, unvaccinated cases of COVID-19 accounted for 95.4 per cent of covid cases, with breakthrough cases accounting for only 0.5 per cent,” said Dr. Kieran Moore.


Moore said people with breakthrough cases can expect an illness with fewer complications.

“The symptoms will be milder, they’ll be shorter, they’ll resolve quicker, there will be less virus in the front of your nose, and the ability to spread virus will be less.”

Family doctor Jennifer Kwan said the Delta variant is showing higher viral loads in those who are infected compared to other variants.

“Right now we need to get as many people vaccinated as possible. We know that these vaccines work even against the Delta variant, at least in preventing severe outcomes.”

Kwan has been crunching the numbers over the course of the pandemic using Google sheets. She said interpreting Public Health Ontario data is more challenging because it currently includes cases from December 2020, a long interval when early on, fewer people were vaccinated.

“The data is showing that people who are fully vaccinated have a much lower risk of severe outcomes, and that the vast majority of hospitalizations, ICU admissions, and deaths are occurring in unvaccinated or partially vaccinated people,” she said in a message to CTV News Toronto.


Kwan points to the fact that between June 12 and July 10, 2021, 11 deaths were reported in the fully vaccinated category (out of 265), and that 10 of the 11 fatalities were over the age of 80.

She also found between the same time period, 84.9 per cent of deaths were in the unvaccinated, compared to 10.9 per cent partially vaccinated and 4.2 per cent in the vaccinated category, tweeting the data with the hashtag #vaccineswork.

“This will help people to make an informed decision about vaccination to protect themselves and their loved ones,” Kwan said.

Dr. Kwong said it’s the unvaccinated, not eligible children, or people who have chosen not to get the shot who are at the greatest risk of hospitalization and death.

“That’s why we really need to convince as many people to get vaccinated as possible,” he said.

“Ontario has a population of about 15 million people and there’s 12 million now vaccinated. There’s bound to be some breakthrough cases but we need to put things into perspective,” he said.

“The vaccine is not 100 per cent effective against infection, seeing these breakthrough cases is expected. It’s not worrisome as long as they are not the people in ICU dying.”