A new study released by the Centers for Disease Control and Prevention (CDC) has concluded that women are more likely to experience side effects after receiving the COVID-19 vaccine. According to the “First Month of COVID-19 Vaccine Safety Monitoring” study published last month, 79% of reports of the more serious symptoms caused by the Pfizer and Moderna vaccines came from women.
The monthlong study followed the first 13,794,904 Americans who received the Pfizer and Moderna vaccines, noting how they reacted to the shots from December 14, 2020, to January 13, 2021. People reported symptoms using the vaccine adverse event reporting system, or VAERS, for the study; the VAERS system also monitored the vaccine’s effect on the body. During this time, the most frequent side effects reported were headache, fatigue, and dizziness, along with 62 cases of anaphylaxis. One hundred and thirteen total deaths were also reported by the study's end, including 78 among long-term care facility residents taking part. By the end of the study, it was found the vaccine’s side effects were overwhelmingly reported by women. Only 62.1% of the actual study participants were women.
Experts have pointed to differences in immune systems between men and women as a reason why one sex reported more symptoms. "We see more autoimmune diseases in women than we do in men and we know the effects of pregnancy on the immune system can be significant," David Wohl, MD, an infectious diseases physician at the University of North Carolina at Chapel Hill School of Medicine, told ABC7 on Saturday. He also explained that women are more likely to report their symptoms to a medical professional compared to men.
Microbiologist and immunologist Sabra Klein, PhD, who works at the Johns Hopkins Bloomberg School of Public Health, echoed the “sex difference” in how people are affected by vaccines in The New York Times earlier this month, stating that it was “completely consistent with past reports of other vaccines.” She also noted that “there is value to preparing women that they may experience more adverse reactions. That is normal, and likely reflective of their immune system working.”
Since the study’s end, Johnson & Johnson’s COVID-19 vaccine has been given approval for usage in Canada, alongside Moderna, Pfizer-BioNTech, and AstraZeneca COVID-19 vaccines. Vaccine eligibility currently varies by province and territory, but many frontline workers, public-facing government and other employees, and people over the age of 70 are among those being given priority. Current estimates say that eligible Canadians over the age of 16 should be vaccinated by the end of June.