Evaluation of post-COVID symptoms of the SARS-CoV-2 Delta and Omicron variants in children: a prospective study.

The post-COVID-19 syndrome is a new syndrome defined in patients with a history of probable or confirmed SARS-CoV-2 infection, usually within three months of the onset of COVID-19, with symptoms and effects lasting at least 2 months. This study is aimed at comprehensively comparing symptoms of the post-COVID-19 syndrome in children with Delta and Omicron variants. This prospective study included children with COVID-19 followed in hospitalized or outpatient clinics in a tertiary hospital. We used a special questionnaire to ask about the presence of persistent symptoms more than 12 weeks after the initial diagnosis. Patients with positive SARS-CoV-2 PCR were selected randomly and grouped according to the dominant variants in our country at that time as follows: Omicron group (after December 16, 2021); Delta (B.1.617.2) group (August 15, 2021, and December 15, 2021). This study included 200 children, 71 of whom were in the Delta group and 129 of whom were in the Omicron group. Weakness (8.5% vs. 1.6%; p = 0.017), the impact of physical efforts (5.6% vs. 3.9%; p = 0.020), fatigue (22.5% vs. 8.5%; p = 0.009), anxiety disorder (12.7% vs. 0.8%; p = 0.001), and gastrointestinal changes (12.7% vs. 4.7%, p = 0.050) were statistically significantly higher in patients with the Delta variant compared to patients with the Omicron variant. There were no differences between the groups regarding anorexia, anosmia/ageusia, arthralgia, influenza-like symptoms, sleeping disorders, decreased physical activity daily, headache, need for analgesia, concentration and memory disorder, and weight loss (p > 0.05).  Conclusion: This study showed that weakness, the impact of physical efforts, fatigue, anxiety disorder, and gastrointestinal changes were more frequent in the Delta group compared to the Omicron group. The incidence of post-COVID-19 syndrome is high in children as well as adults and affects several systems; therefore, it should be kept in mind that children should be followed for post-COVID-19 syndrome. What is Known: • Despite the milder severity of acute COVID-19 in children, post-COVID-19 symptoms may occur. The post-COVID-19 condition is complex and novel, especially in the pediatric population. What is New: • Post-COVID-19 symptoms in children differ depending on the viral variant. Post-COVID-19 syndrome has a great impact on the social life of children which may have serious and long-term effects.