Have a fever after vaccination? Scientists have discovered new potential connections

A messenger RNA vaccine is a vaccine that uses a small portion of the viral genetic material messenger RNA (mRNA) to help the body's immune system recognize and fight the virus
that causes COVID-19.
mRNA vaccines have been shown to be effective in preventing COVID-19 infection and have been authorized by
regulatory agencies around the world.

There have been concerns about the side effects of mRNA COVID-19 vaccines, such as fever and fatigue, which are often considered normal and transient
.
However, the relationship between these adverse effects and antibody production after vaccination has not been well studied
.

A group of researchers at Okayama University recently conducted a study to test this link
.
They recruited 49 university staff and students who had not previously had COVID-19 and found a relationship between fever incidence and antibody counts, especially after
the third dose of the vaccine.
Their findings were published in the Journal of Epidemiology
.

The mRNA vaccine mimics the surface structure
of SARS-CoV-2 in the body.
Immune cells then recognize these invading pathogens and produce antibodies
against them.
Therefore, antibody counts can be used to quantify the immune system's response
to vaccination.

Dynamics of immunoglobulin G (IgG) in the first week after vaccination due to the presence or absence of postvaccination fever
.
The red and blue lines were the average
IgG concentrations predicted by the mixed-effects model in the febrile and non-febrile groups, respectively.
The area of each color represents the 95% confidence interval (CI)
of the regression curve.
Day 0 is negative due to the impact of modeling
predictions.
Source: Yorifuji Takashi, Okayama University

All participants were investigated
for adverse reactions one week after receiving the third dose of mRNA-1273 vaccine.
Meanwhile, antibody levels
were measured in all subjects before, 3 days after vaccination, 1 week after vaccination, and 1 month after vaccination.
Using statistical modeling, the correlation
between fever incidence and antibody levels at different time points was specified.
To explain the factors that contribute to fever after vaccination, the team also looked at participants' gender, age differences, allergy history, and use of fever-reducing drugs (fever-reducing drugs
).

Then, based on the results of the survey, the subjects were divided into a "fever" group and a "no fever" group
.
The study found that the fever group was more likely to be younger people (20 to 49 years old) and had a history
of allergies.
Next, antibody levels
at different time points in both sets were analyzed.
At 1 week after vaccination, antibody counts were significantly higher in the fever group than in the non-fever group
.
However, there appears to be no correlation
between the incidence of fever and high antibody levels 1 month after vaccination.

This is the first study
to highlight the relationship between fever induction and antibody levels at different time points after the third dose of mRNA-1273 vaccine.
"Antibody titers after mRNA-1273 vaccination may be faster in people with fever after vaccination, but the difference may not be significant
1 month after vaccination," the team concluded.
The researchers also note that while these conflicting observations may not be clinically significant, larger studies may provide better insights
.

References: "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.