Study links side effects of Covid vaccines to better immune response

Vaccination against Covid-19 contributes to preventing the development of serious illness and death from the infection. In general, people who have been vaccinated have mild reactions such as pain or tenderness and swelling at the injection site, as well as a low-grade fever and body ache.

People can also experience fatigue and chills, according to the World Health Organization (WHO). Symptoms can appear at the time of application, or between 24 and 48 hours, and disappear in a few days.

A US study reveals that people vaccinated with Pfizer or Moderna immunizers who had symptoms such as fever, chills, muscle aches, or fatigue had a higher antibody response. The results were published in the scientific journal JAMA.

“In conclusion, these findings support the understanding of post-vaccination symptoms as signs of vaccine efficacy and reinforce guidelines for vaccine boosters in the elderly,” the article reads.

How the analyzes were performed

The researchers point out that messenger RNA vaccines are associated with both local and systemic symptoms. However, there are few studies that assess whether post-vaccination symptoms are associated with the vaccine-induced antibody response.

Participants in an ongoing project called the Framingham Heart Study (FHS), which studies risk factors for cardiovascular disease, were evaluated in the research. In February of this year, volunteers were invited to answer questionnaires about vaccination against Covid-19 and associated symptoms, in addition to submitting samples for antibody tests.

The study included data from participants who received two doses of one of the vaccines, Pfizer or Moderna, at least two weeks before the blood draw.

Post-vaccination symptoms were categorized as systemic symptoms (fever, chills, muscle pain, nausea, vomiting, headache, or moderate to severe fatigue) or local symptoms (injection site pain or skin rash).

IgG-type antibodies, which point to longer-lasting protection, for the coronavirus were measured. Associations between post-vaccination symptoms and antibody response were also evaluated.

What do the results say

Of the 3,200 eligible participants in the study, 928 (29%) completed the questionnaire, had a blood sample taken, and reported receiving two doses of either Pfizer or Moderna vaccines. The average age of respondents was 65 years, 360 (39%) were men and 568 (61%) were women. In all, 84 (9%) reported having had a previous Covid-19 infection.

After any of the vaccine doses, 446 participants (48%) reported systemic symptoms, 109 (12%) reported only local symptoms, and 373 (40%) reported no symptoms. In the analysis, symptoms were associated with younger age, female gender, previous infection, and Moderna vaccine.

Antibody reactivity was observed in 365 asymptomatic participants (98%), 108 participants (99%) with only local symptoms, and 444 participants (99%) with systemic symptoms. According to the study, systemic symptoms were associated with a greater antibody response. Similar results were obtained with the exclusion of participants with previous coronavirus infection.

“In a sample of older, twice-vaccinated US adults, self-reported systemic symptoms following SARS-CoV-2 mRNA vaccination were associated with a greater antibody response. versus only local symptom or no symptoms. These results agree with a previous study in US healthcare providers that showed higher post-vaccination antibody measurements among those with significant symptoms following an mRNA vaccine,” the study reads.

The researchers say that nearly all of the participants showed a positive antibody response to the full series of vaccines. However, systemic symptoms remained associated with a greater antibody response. They highlight that further studies are needed to clarify the biological mechanisms associated with differences in immune response after vaccination.