Long COVID Prevalence and Severity in Vaccinated Versus Unvaccinated Children

Although most studies of post-COVID-19 conditions focus on adults, children can also experience long COVID. However, it is not clear whether COVID-19 vaccination in children, like adults, reduces the likelihood and severity of long COVID.

At this week’s 2023 European Congress of Clinical Microbiology & Infectious Diseases (ECCMID), one study sought to document the differences in post-COVID-19 conditions between vaccinated and unvaccinated children.

The children evaluated in this study were recruited from the Diagnosis and Support for COVID Children to Enhance Recovery (DISCOVER) cohort, conducted at China Medical University Children’s Hospital in central Taiwan. Included participants were children under the age of 18 years who had previously tested positive for COVID-19 infection during the Omicron pandemic.

The children presented to the outpatient department with post-COVID-19 conditions between July 1-September 30, 2022. Because there is no pervasive definition of long COVID, the study authors defined “post-COVID-19 condition(s)” as persisting symptoms for 4 weeks after recovering from acute COVID-19 infection. The investigators assessed the clinical characteristics of children meeting these criteria.

A total of 247 with long COVID were included in this study, 127 who had received at least 1 dose of an authorized COVID-19 vaccine and 120 who were unvaccinated. The cohort was 58.7% male (n = 145), and 80.6% were younger than 10 years of age (n = 199).

The most common acute COVID-19 symptom was fever, which occurred in 94.2% of unvaccinated children and 79.5% of vaccinated children. Hospitalization during acute infection occurred in 7.3% of the children (n = 18), and 83.3% of hospitalized children were unvaccinated (n = 15).

After acute infection, post-COVID-19 conditions were proportionally higher in unvaccinated children than in children who had been vaccinated against COVID-19.

Long COVID conditions included:

• Breathlessness (44.9% of unvaccinated children, 30.0% of vaccinated)
• Fatigue (37.0% of unvaccinated children, 22.5% of vaccinated)
• Headache (26.0% of unvaccinated children, 14.2% of vaccinated)
• Dizziness (28.3% of unvaccinated children, 15.0% of vaccinated)
• Heart palpitations (26.8% of unvaccinated children, 10.8% of vaccinated)
• Myalgia (17.3% of unvaccinated children, 7.5% of vaccinated)

“Larger longitudinal cohort studies are necessary to determine the long-term effects of COVID-19 vaccination in children with post-COVID-19 conditions,” the study authors wrote, but the results of this relatively small study of children found long COVID was more prevalent and severe in unvaccinated children than in children who had received at least 1 dose of a COVID-19 vaccine.

This study, “Different clinical presentations of post COVID-19 conditions between vaccinated and unvaccinated children after SARS-CoV-2 Omicron variant infection in Taiwan,” was presented during a poster session at ECCMID 2023.