Adverse events of AstraZeneca’s Covid-19 vaccine occurred more in women and younger people among healthcare workers in Korea, a medical report said.
The research team at the Asan Medical Center polled 5,866 out of 7,625 healthcare professionals who received vaccination and published the results in the Journal of Korean Medical Science (JKMS).
Out of the 5,866 participants, 5,589 had the AZ shot and 277, the Pfizer vaccine.
The results showed that 92.7 percent of the vaccinated experienced at least one adverse event within three days after vaccination. Adverse reactions appeared in 93.3 percent of the AZ vaccine group, which was significantly higher than those of the Pfizer vaccine group at 80.1 percent.
Also, all types of adverse events occurred more in the AZ vaccine group than in the Pfizer group. Injection-site pain, which is the most common local adverse reaction, occurred in 81.2 percent of the AZ vaccine recipients versus 70 percent of the Pfizer vaccine recipients. In both groups, muscle pain, fatigue, and headache were the most common systemic reactions.
Neurologic reactions, including paraesthesia and allergy-like reactions such as swelling in the throat, were significantly more commonly reported in the AZ vaccine group, the research team said.
While the Pfizer vaccine group did not show much difference in the frequency of adverse reactions according to age groups, the AZ vaccine group demonstrated more frequent side effects in females and younger people. Among those in their 20s and 30s who received the AZ vaccine, 96 percent reported adverse reactions. The proportion went down to 92.9 percent in their 40s, 84.2 percent in their 50s, and 65.1 percent in their 60s.
In the AZ vaccine group, 95 percent of the women and 87.7 percent of the men experienced adverse reactions.
The frequency of adverse reactions gradually decreased over the three days after vaccination in both groups.
The research team confirmed that the frequency of adverse reactions was significantly higher in those who received the AZ vaccine than those who received the Pfizer vaccine.
“The adverse reactions were more commonly reported in females and those in the younger age groups,” the research team said. “The frequency and severity of adverse reactions associated with the AZ vaccine should be taken into account when planning mass immunization, especially in females and younger age groups.”