All subjects were surveyed for adverse reactions a week after they received the third mRNA-1273 vaccine dose. Simultaneously, antibody levels of all subjects were measured just before receiving the vaccine, 3 days after, ~1 week after, and finally 1 month after the dose. Using statistical modeling, correlations between the incidence of fever and antibody levels at various time points were stipulated. To account for factors contributing to the onset of fever post-vaccination, the team also looked at sex, age differences, a history of allergy, and the use of antipyretics (fever-reducing drugs) amongst the participants.
The subjects were then classified into a “fever” or “non-fever” group based on the survey results. It was found that the fever group was more likely to be younger (20 to 49 years old) and had a past history of allergies. Next, antibody levels at different time points in the two groups were analyzed. At 1 week post-vaccination, the fever group had substantially higher antibody counts than the non-fever group. However, at 1-month post-vaccination there seemed to be no correlation between the incidence of fever and high antibody levels.
This is the first study to highlight associations between the induction of fever and antibody levels at various time points after the third dose of the mRNA-1273 vaccine. “Antibody titers after mRNA-1273 vaccination may be faster in the group with post-vaccination fever, but the difference may not be significant 1-month post-vaccination,” concludes the team. The researchers also suggest that while these contradictory observations may not have significant clinical relevance, a study with a larger sample size might provide better insights.
Reference: “Association Between Fever and Antibody Titer Trends After a Third Dose of the mRNA-1273 Vaccine” by Naomi Matsumoto, Tomoka Kadowaki, Rumi Matsuo, Ayako Sasaki, Chikara Miyaji, Chigusa Higuchi, Masanori Nakayama, Yasue Sakurada, Hideharu Hagiya, Soshi Takao, Fumio Otsuka and Takashi Yorifuji, 5 December 2022, Journal of Epidemiology.