# Comparison of Transient and Persistent Adverse Events After COVID-19 Vaccination: A Retrospective Analysis

## TL;DR

This study compares short-term and long-term side effects after COVID-19 vaccination, finding that persistent symptoms like pain are more common after second doses and linked to a specific booster vaccine.

## Contribution

The study identifies a novel association between persistent adverse events and the bivalent omicron-containing booster vaccine (BA.1), particularly in women in their 40s.

## Key findings

- Persistent symptoms were more common after second and subsequent vaccinations compared to first doses.
- Pain was significantly more frequent in the persistent group (60%) than in the transient group (13.6%).
- The bivalent omicron-containing booster vaccine (BA.1) was significantly more common in the persistent symptom group.

## Abstract

Objective: Most reported adverse events following COVID-19 vaccination have been transient. However, persistent adverse events may occur with some frequency. This study aimed to analyze patient background characteristics and trends, with a focus on whether adverse events following COVID-19 vaccination were transient or persistent.

Methods: A retrospective study was performed at a single institution in Japan.

Patients: The study cohort included 47 patients who presented with symptoms after COVID-19 vaccination between May 2021 and September 2023. The patients were classified into two groups based on the duration of symptoms: transient group, less than four weeks; persistent group, greater than or equal to four weeks. Data on age, sex, body mass index, smoking history, underlying conditions, type of COVID-19 vaccination, number of doses, onset, symptoms, and treatments were collected retrospectively.

Results: The median age was 51.0 years and 74.5% were females, with a particularly high proportion of women in their 40s. The use of the bivalent omicron-containing booster vaccine (BA.1) was significantly more common in the persistent group than in the transient group (p = 0.0267). Onset in the transient group was more common after the first vaccination, whereas onset in the persistent group was more common after the second and subsequent vaccinations (p = 0.003). Regarding symptoms, pain was more frequent in the persistent group than in the transient group (60% vs. 13.6%; p = 0.001).

Conclusions: This study investigated the presence of persistent symptoms, especially pain, after COVID-19 vaccination. Persistent symptoms were frequently reported after the second vaccination. It should be noted that the study does not negate the usefulness of COVID-19 vaccines.