Backgrounds:

SARS-CoV-2 variant Omicron (B.1.1.529) is causing the actual wave in Spain, leading to the highest cumulative incidence across the pandemic. It is not known whether this variant causes more severe disease in children.

Methods

Clinical features were collected from children attended at the Emergency Room (ER) at a secondary center in Madrid from December 20^th 2021 to January 2^nd 2022. Charts were reviewed 1 week after diagnosis to check potential complications. Data were compared to children with other variants included in the national COVID-19 database EPICO-AEP. In this comparison, 17 ambulatory patients with Omicron from other center were also included to make data more robust.

Results:

94/1360 children (9.6%) had COVID-19. In 16% of them, variant was identified: 87% Omicron, 13% Delta. Median age was 6.5 years, only 7% were >12 years. Final diagnosis were upper respiratory tract infection (URTI) 61/94 (65%), flu-like syndrome 15/94 (16%), gastroenteritis 7/94 (7%), fever without source (FWS) 3/94 (3%), and migraine or asthma flare 2/94 each (2%). Only 2/94 (2%) patients were hospitalized: a 3-year girl with features of bacterial pneumonia and an Omicron variant; and a 40-days-old infant with whooping-like cough with negative RT-PCR for both Bordetella pertussis and RSV. Hospitalization rate was similar in Omicron and Alpha variant waves (2% vs 4%, p=0.656). Compared to other waves, URTI, headache and fever were more frequent in the Omicron wave, while pneumonia and FWS were in previous waves.

Conclusions/Learning Points:

Children with COVID-19 and Omicron variant seem to have similar profile as other variants, only more fever and URTI and less pneumonia.. Most children were <12 years, which may be related to the high proportion of vaccinated adolescents in our population.

Backgrounds:

Multisystem inflammatory syndrome in children (MIS-C) is a condition characterized by a dysregulated response of the immune system 2-6 weeks after a SARS-CoV-2 infection. Some authors hypothesized that the COVID-19 vaccine could trigger a new exaggerated response in these children.

Our aim was to assess the proportion of vaccinated children and the incidence of new MIS-C or myocarditis after vaccination in adolescents with previous MIS-C.

Methods

From the Epidemiological Study of COVID-19 in Children of the Spanish Pediatric Association, we contacted researchers from centers with ≥3 MIS-C patients aged 12-18 years old by October 31, 2021, hospitalized from March 2020, through October 2021 and fulfilling WHO criteria for MIS-C.

We performed a semi-structured telephonic interview with the caregivers and/or the adolescents, about vaccination acceptance and adverse events after vaccination.

Results:

An interview was possible in 42/48 (87.5%) selected adolescents, being mainly male (30/42, 71.4%) and, at MIS-C diagnosis, their median age was 13.1 years old. 32/42 (76.2%) patients had received COVID-19 vaccine. The median time between MIS-C diagnosis and vaccination was 42 weeks and the telephonic interview took place after a median of 10.0 weeks (range 5.3-19.7) post-vaccination. After vaccination, 22/32 (68.8%) patients reported adverse events, being 86.7% mild and 3.3% moderate (Table1). No new MIS-C or myocarditis or pericarditis episodes were reported.

Conclusions/Learning Points:

In this study, we describe a high acceptance and low incidence of relevant adverse events after COVID-19 vaccines in a population of adolescents with a previous MIS-C diagnosis. No new MIS-C episodes or myocarditis occurred after a median of 10 weeks post-vaccination. The results of this study are reassuring and may help to decide for patients with previous MIS-C who are considering COVID-19 vaccination.