COVID-19 mRNA vaccines are highly effective in protecting people with immune-related inflammatory diseases against hospitalization and death, a new Canadian study suggests.
According to Canada’s COVID-19 Immunity task Force, more than seven million Canadians suffer from immune-mediated inflammatory diseases (IMID), which can include various types of arthritis and inflammatory bowel disease (IBD). There has been limited research however, into vaccine effectiveness for Canadians in these groups because they were excluded from the clinical trials for these vaccines, researchers said.
According to results of a peer-reviewed, population-based study published in The Lancet Rheumatology on April 14, 2022, mRNA vaccines were 92 to 97 per cent effective against severe infections during the Alpha and Delta waves for those in Ontario living with rheumatoid arthritis, ankylosing spondylitis, a type of arthritis that usually affects the spine, the skin condition psoriasis, and IBD. These results were similar to those for the province’s general population.
Effectiveness against overall infection for those with IMIDs, however, was lower than the wider population, which was estimated to be above 90 per cent for the pre-Omicron variants. For those with rheumatoid arthritis, two doses were found to be 83 per cent effective, among those with ankylosing spondylitis it was 89 per cent, for psoriasis it was 84 per cent, and for IBD it was 79 per cent.
Individuals with these types of diseases can be more vulnerable to severe COVID-19 infections because they often take immunosuppressants that can weaken their immune system.
For all four disease groups studied, scientists found that those who received Moderna’s Spikevax had better protection compared with those who were given Pfizer-BioNTech’s Comirnaty vaccine.
While effectiveness peaked between 31 and 60 days after vaccination and waned over time, researchers said the shots remained highly effective in protecting recipients even 120 days after the second dose. Effectiveness rebounded among those who received a third shot.
“Many of these patients have tried numerous treatments to achieve good disease control and regain function,” said the study’s senior author and rheumatologist Dr. Sasha Bernatsky in a statement. Bernatsky is a professor with the Research Institute of McGill University Health Centre.
“At the same time, the drugs patients require to manage their conditions may also increase their susceptibility to infection. These findings, up to November 2021, demonstrate that it is possible for individuals with IMID to achieve adequate protection via COVID vaccination.”
Data was based on PCR results between March 1 and Nov. 22, 2021 for those 16 and over living with IMIDs in Ontario. Researchers found 2,127 test-positive cases in a group of 36,145 people with rheumatoid arthritis, 476 positive cases in a group of 7,863 with ankylosing spondylitis, 3,089 positive cases among 47,199 individuals with psoriasis, and 1,702 positive cases in a group of 31,311 people with IBD. Long-term care residents were excluded because they are tested frequently and are more frail.
“By linking a centralised vaccine registry with laboratory and health administrative data, we created large cohorts to study vaccine effectiveness, overcoming the sample size challenges faced by clinical studies,” researchers wrote in the paper.
While efforts were made to reduce problems including selection bias, the authors cautioned that there could still be some bias due to unmeasured differences between vaccinated and unvaccinated patients, and potential differences in testing patterns between those who were vaccinated and those who were not.
The authors also noted that information on symptoms at the time of testing was only available for some patients, so they were unable to evaluate the vaccine’s effectiveness against symptomatic infection. Researchers also did not analyze the effects or control for immunosuppressant medications, because the data for prescription drugs was limited to a subgroup of patients.
The data collection ended on Nov 22, when the first cases of Omicron were detected in the province in order to limit misclassification of variants. Researchers also limited their research for several other reasons as well, including marked differences with the Omicron variant, high vaccine coverage among those within the disease groups studied and vaccine passports that could result in bias, and more restricted PCR testing in Ontario.
Because the study ended shortly after third doses were authorized in Ontario, the authors noted that more research was needed to determine the effectiveness of three doses over time, especially against new variants.
“Our encouraging findings begin to give a clearer picture of vaccine effectiveness in those with IMIDs,” Dr. Jessica Widdifield, lead author of the study and a scientist in the Holland Bone and Joint Program at Sunnybrook Health Sciences Centre said in a statement.
The study is a collaboration of scientists from Sunnybrook Health Science Centre, IC/ES, and the Research Institute of the McGill University Health Centre and was supported by the federal government’s COVID-19 Immunity Task Force.
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