A major Canadian government-funded study involving more than 567,000 vaccinated adults has reported elevated rates of medically significant health events following COVID-19 mRNA vaccination, with the strongest safety signals linked to Moderna’s mRNA-1273 vaccine.
The nationwide study, published in the journal Vaccine, tracked adverse events severe enough to disrupt daily activities, require medical attention, or lead to emergency care, according to Trial Site News.
The research was conducted through the Canadian National Vaccine Safety Network (CANVAS) and led by investigators including Julie A. Bettinger of the BC Children’s Hospital Research Institute and Matthew P. Muller of Unity Health Toronto. Researchers prospectively monitored 567,781 adults after a first vaccine dose, 301,717 after a second dose, and compared outcomes against 14,984 unvaccinated controls.
According to the study, medically significant health events were reported at higher rates among vaccinated participants compared with the unvaccinated control group. Adjusted relative risks were reported as 2.3 times higher after a first Pfizer dose, 3.2 times higher after a first Moderna dose, 2.9 times higher after a second Pfizer dose, and seven times higher after a second Moderna dose. Researchers found the second Moderna dose produced the highest overall event rate, affecting 11.1% of recipients.
The most commonly reported symptoms included fatigue, fever, headache, dizziness, gastrointestinal issues, chest pain, palpitations and joint pain. Most reactions reportedly occurred within 24 hours of vaccination and resolved within several days.
The study also identified statistically significant increases in emergency department visits and hospitalisations following Moderna vaccination. Researchers documented cases of myocarditis, pericarditis, appendicitis, pancreatitis, myocardial infarction, stroke-like events and anaphylaxis occurring shortly after vaccination.
Investigators recorded 28 myocarditis or pericarditis cases within seven days of vaccination, with the highest rate occurring after a second Moderna dose at 12.59 cases per 100,000 recipients, compared with 3.72 cases per 100,000 after a second Pfizer dose. Around one-third of those cases required hospitalization, with approximately half occurring in adults aged 20 to 29 years. No myocarditis or pericarditis cases were reported in the unvaccinated control group.
Among hospitalised participants, appendicitis emerged as the most common diagnosis reported after vaccination, with 12 cases identified within seven days of receiving an mRNA vaccine. Researchers noted that hospitalization rates remained low overall and stated that observed appendicitis rates were within expected background levels, although they acknowledged previous international surveillance data had identified similar signals.
The study also reported that all identified anaphylaxis cases occurred in women, with several requiring intensive care treatment.
Researchers cautioned that the unvaccinated control group was considerably smaller than the vaccinated cohort, limiting comparisons for rare outcomes. The study focused primarily on short-term adverse events and no long-term health outcomes were studied.
Image credit: Getty Images
What’s everyone worried about? Perfectly safe and effective. I dont understand why there’s such a poor uptake of the boosters. These beautiful vaccines our dear Mr T bought to the world with warpspeed, we should be grateful.
The A-Team ended decades ago.
Mr T has passed away.
You need to move on, friend.
Well who would of thought it?
I’d love to shove all these studies down the fat throats of the scum in the beehive.
Every day all I see is more and more evidence that I made the correct choices.
All together now “safe and effective!”
Hello. I’m an idiot and I’m off to get my booster.
Has anyone else noticed an increase in people wearing face masks lately?