Ottawa researchers investigating COVID-19 vaccine efficacy in cancer patients

Researchers in Ottawa are examining how effective COVID-19 vaccines are in cancer patients.

Dr. Glenwood Goss with the Ottawa Hospital Cancer Centre is lead researcher on a government-funded study that will measure vaccine efficacy in people with different types of cancer.

“The original large studies that were done with the initial vaccines excluded patients who had autoimmune disease or any immunosuppressed condition of which cancer is one. So we don’t have good data on the efficacy of the COVID-19 vaccine in the cancer population. There are 2.1 million Canadians who suffer from cancer and so it is a significant public health issue,” he said.

Goss said what is currently known is based on two small studies conducted in the U.K. and in the U.S. and Switzerland.

“We know that after the first dose, the immune response is lower than the in the normal population. That’s what came out of these studies. After the second dose, it really depends on which cancer population you’re looking at.”

He said based on the studies, people with hematological malignancies or blood cancers did not respond as well as the general population after a second dose. In general, those with other types of cancer – provided that they were not undergoing chemotherapy – appeared to have a robust response, similar to the general population, while those who were undergoing chemotherapy had a lower antibody response.

Still, Goss said, those studies were rather small and had some issues.

The Ottawa Hospital study is much larger in scale and will compare three groups: one control group, one group of patients with cancer but not in cancer therapy, and another group of patients with cancer and who are undergoing cancer therapy.

Participants are still being recruited. The plan is to follow them over the course of a year, checking in at multiple points.

“We’ll have a clearer idea of what is happening with their antibody levels and their immune response in general. And remember with vaccines what is important is memory. So for how long does the vaccine work?” Goss explained.

The study is intended to help drive public policy. As discussions grow around potential booster shots, the data gathered will help inform health officials on whether booster shots might be necessary for cancer patients in particular.

“I think in a vulnerable population like the cancer population, it is likely that booster shots will be necessary down the line but we don’t have the data to support that at this time,” Goss said.

In the U.S., federal regulators have already given the green light to allow additional doses for some vulnerable populations.

Here in Canada, the nation’s expert panel on vaccines says whether a third dose would be beneficial remains unclear.

In a statement to CityNews, Health Canada said in part: “NACI continues to closely monitor emerging evidence concerning the effectiveness of COVID-19 vaccines in those who are immunosuppressed, including evidence on the potential need or benefit of a third dose in this population.”

Preliminary results from the Ottawa Hospital study likely won’t be available until some time next year.