Immunocompromised people should get 3rd COVID-19 vaccine dose, Ontario study finds

When double lung and kidney transplant recipient Sara Murray of Acton, Ont., received her second dose of the COVID-19 vaccine a few months ago, she was hoping for some “freedom.”

“I can easily pick up illnesses. And it’s difficult for me to fight them because my immune system is shut down,” she told Global News in March.

As Murray recently discovered, however, two doses of the vaccine have offered her no protection against the virus.

“I went and got the blood work done to see and I got my results back and I had no antibodies. I had 0.1 units per millilitre, which works out to nothing,” she said.

“We know that the general population of people who are not immunosuppressed get a very nice response and when we look at transplant patients, they get a significantly lower response. Maybe only about 18 to 50 percent of patients will get the kind of same antibody response as the general population after two doses,” explained Dr. Darren Tuen, a kidney transplant physician at St. Michael’s Hospital.

Double-lung transplant Derek Clark also did an antibody test to find out what sort of protection he has after two doses of the Pfizer-BioNTech vaccine.

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“I came back negative, which essentially means that I have no detectable antibodies,” he said.

Clark said a lack of protection means while the rest of Ontario is in Step 3 of its pandemic reopening, he still lives as if he’s in Step 1.

“I feel vulnerable. I don’t feel safe … I can’t really go indoors. I can’t go to a concert or a wedding or a sporting event indoors. It’s simply not safe for me to do so,” said Clark.

UHN transplant infectious diseases physician Dr. Deepali Kumar said a third dose may be helpful for people like Murray and Clark.

“We’re talking about people that are immunocompromised so that includes transplant patients, patients who are receiving chemotherapy or other immunosuppressive conditions,” said Kumar.

Researchers at the University Health Network said findings released this week indicate a third-dose booster will increase protection in transplant recipients.

“We found that with two doses of mRNA vaccine that you just don’t get the protection you need if your immune system is weak and we need to find ways to increase that protection, especially now with the Delta variant circulating,” said Kumar. 

“In a transplant recipient, we often find the antibodies are undetectable after two doses of vaccine.”

“What we found in our study was that we had a number of people who were exactly like this … who then became positive after the third dose of vaccine so I think that gives a glimmer of hope to people that maybe they just need that one more shot to mount a positive antibody response,” she said.

“There were some people in the study who had low antibody responses that came right up to the level of a healthy person.”

In the meantime, doctors recommended immunocompromised individuals maintain precautions like masking and physical distancing.

Kumar said the general population also has a role to play to keep immunocompromised people safe.

“Everybody around a transplant patient should get their two doses of the vaccine. That’s called ‘ring vaccination’ or ‘cocooning’ is the word that we use and that is also a very effective way of being protected,” she said.

Clark has a message for the public as he said he awaits word on a third dose of the vaccine.

“While you may have doubts about the vaccine, the reality is that you are protecting all of those individuals across the country that are immunocompromised and so we need to look at the big picture. We need to do the right thing for all Canadians, and we need to make sure that layer of protection is there,” he said.