Psychological factors associated with reporting side effects following COVID-19 vaccination: A prospective cohort study (CoVAccS - Wave 3).

Objective: To investigate symptom reporting following the first and second COVID-19 vaccine doses, attribution of symptoms to the vaccine, and factors associated with symptom reporting.

Methods: Prospective cohort study (T1: 13-15 January 2021, T2: 4-15 October 2021). Participants were aged 18 years or older, living in the UK. Personal, clinical, and psychological factors were investigated at T1. Symptoms were reported at T2. We used logistic regression analyses to investigate associations.

Results: After the first COVID-19 vaccine dose, 74.1% (95% CI 71.4% to 76.7%, n = 762/1028) of participants reported at least one injection-site symptom, while 65.0% (95% CI 62.0% to 67.9%, n = 669/1029) reported at least one other (non-injection-site) symptom. Symptom reporting was associated with being a woman and younger. After the second dose, 52.9% (95% CI 49.8% to 56.0%, n = 532/1005) of participants reported at least one injection-site symptom and 43.7% (95% CI 40.7% to 46.8%, n = 440/1006) reported at least one other (non-injection-site) symptom. Symptom reporting was associated with having reported symptoms after the first dose, having an illness that put one at higher risk of COVID-19 (non-injection-site symptoms only), and not believing that one had enough information about COVID-19 to make an informed decision about vaccination (injection-site symptoms only).

Conclusions: Women and younger people were more likely to report symptoms from vaccination. People who had reported symptoms from previous doses were also more likely to report symptoms subsequently, although symptom reporting following the second vaccine was lower than following the first vaccine. Few psychological factors were associated with symptom reporting.