Association of Self-reported Systemic Reactions Following SARS-CoV-2 Vaccination With Immunological Response in the Danish National Cohort Study of Effectiveness and Safety of SARS-CoV-2 Vaccines (ENFORCE)

Abstract

Background: Side effects to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines are a key concern contributing to vaccine hesitancy, but more individuals may be encouraged if SARS-CoV-2 vaccines were known to lead to a stronger immune response. Methods: Included were adult participants from the Danish National Cohort Study of Effectiveness and Safety of SARS-CoV-2 Vaccines (ENFORCE) who completed a questionnaire to assess systemic reactions following SARS-CoV-2 vaccination (BTN162b2, mRNA-1273, ChAdOx1) and had SARS-CoV-2 spike immunoglobulin G (IgG) levels measured at baseline and post-vaccine. A symptom score was developed to measure severity of systemic adverse reactions (+1 for each moderate, +2 for each severe). Post-vaccination SARS-CoV-2 spike IgG levels were compared between participants with different scores using multivariable linear regression. Results: A total of 6528 participants were included (56.3% females; median age [interquartile range], 64 [54-75] years). After the first vaccination, no association was found between symptom score and post-vaccine dose spike IgG level (P =. 575). Following the second vaccination, significantly higher spike IgG levels were observed according to higher symptom scores (P