Variation in SARS-CoV-2 seroprevalence in children in the region of Asturias, Northern Spain.

BACKGROUND: Updated seroprevalence estimates are important to describe the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) landscape and to guide public health decisions. The aims are to describe longitudinal changes in seroprevalence in children in a region in Northern Spain and to analyze factors associated with SARS-CoV-2 seropositivity. METHODS: Prospective multicenter longitudinal study with subjects recruited from July to September 2020. Children (up to 14 years old) were included and followed up until September 2021. Venous blood samples were collected every six months during three testing rounds and were analyzed for SARS-CoV-2 antibodies. The data regarding epidemiological features, contact tracing, symptoms, and virological tests were collected. The evolution of SARS-CoV-2 seroprevalence during the study and the differences between children with positive and negative SARS-CoV-2 antibody tests were analyzed. RESULTS: Two hundred children were recruited (50.5% girls, median age 9.7 years). The overall seroprevalence increased from round 1 [1.5%, 95% confidence interval (CI) 0.3%-4.3%] to round 2 (9.1%, 95% CI 4.6%-12.7%) and round 3 (16.6%, 95% CI 9.5%-19.6%) (P < 0.001). Main changes occurred in children aged zero to four years (P = 0.001) who lived in urban areas (P < 0.001). None of the children who were previously positive became seronegative. Following multivariable analysis, three variables independently associated with SARS-CoV-2 seropositivity were identified: close contact with coronavirus disease 2019 (COVID-19) confirmed or suspected cases [odds ratio (OR) = 3.9, 95% CI 1.2-12.5], previous positive virological test (OR = 17.1, 95% CI 3.7-78.3) and fatigue (OR = 18.1, 95% CI 1.7-193.4). CONCLUSIONS: SARS-CoV-2 seroprevalence in children has remarkably increased during the time of our study. Fatigue was the only COVID-19-compatible symptom that was more frequent in seropositive than in seronegative children.

Change on the Circulation of Respiratory Viruses and Pediatric Healthcare Utilization during the COVID-19 Pandemic in Asturias, Northern Spain.

(1) Background: The COVID-19 pandemic and the implementation of restrictions and nonpharmaceutical interventions (NPIs) changed the trends in respiratory viral circulation and the pattern in pediatric healthcare utilization; (2) Methods: A retrospective, multicenter observational study designed to analyze the impact of the pandemic on pediatric healthcare utilization and the viral circulation pattern in children in a region in Northern Spain was carried out. Viral diagnostics data from all nasal or pharyngeal swabs collected in children in Asturias during the periods of March 2018-September 2019 and March 2020-September 2021 were analyzed, as well as the number of pediatric hospitalizations and emergency visits; (3) Results: A total of 14,640 samples were collected during the pandemic period. Of these, at least one respiratory virus was detected in 2940 (20.1%) while 5568/10,298 samples were positive in the pre-pandemic period (54.1%); p < 0.001. The detection of both enveloped and non-enveloped viruses decreased among periods (p < 0.001). After week 14, 2020, enveloped viruses were no longer detected until one year later, while non-enveloped viruses continued to be detected in children. Overall, a mean of 4946.8 (95% CI 4519.1-5374.4) pediatric emergency visits per month during the period 2018-2019 as compared to 2496.5 (95% CI 2086.4-2906.5) for 2020-2021 occurred (p < 0.001). The mean of pediatric hospitalizations also significantly decreased between periods, as follows: 346.6 (95% CI 313-380.2) in 2018-2019 vs. 161.1 (95% CI 138.4-183.8); p < 0.001; (4) Conclusions: Our study showed a remarkably reduction in pediatric hospitalizations and emergency visits and a change in the pattern of viral circulation during the COVID-19 pandemic in Asturias. The usual seasonal respiratory viruses, namely influenza or RSV were nearly absent in the pediatric population during the pandemic.