BackgroundSeasonal influenza virus vaccination should be considered in all pediatric patients with rheumatic diseases. Few studies have addressed influenza vaccination safety and efficacy in this group. We aim to prospectively evaluate immunogenicity and safety of the trivalent inactivated influenza vaccine including A/H1N1, A/H3N2 and B strains in children with juvenile idiopathic arthritis (JIA) receiving biological therapy.MethodsThirty-five children diagnosed with JIA and 6 healthy siblings were included. Serum samples were collected prior to, 4-8 weeks and one year after vaccination. Microneutralization assays were used to determine neutralizing antibody titers. The type and duration of therapy were analyzed to determine its effect on vaccine response. Clinical data of the participants were collected throughout the study including severe adverse events (SAE) and adverse events following immunization (AEFI).ResultsTwenty-five patients (74.3%) received biological treatment for JIA; anti TNF-α was prescribed in 15, anti IL-1 receptor in 4 and anti IL-6 receptor therapy in 6 children. The seroprotection rate 4-8 weeks after vaccination in the JIA group was 96% for influenza A/(H1N1)pdm and influenza A/H3N2, and 88% for influenza B. No differences were found in GMT, seroprotection and seroconversion rates for the three influenza strains between the control group and patients receiving biological therapy. Furthermore, long-term seroprotection at 12 months after vaccination was similar in patients receiving either biological or non-biological treatments. No SAEs were observed.ConclusionsIn this study, influenza vaccination was safe and immunogenic in children with JIA receiving biological therapy.Electronic supplementary materialThe online version of this article (doi:10.1186/s12969-017-0190-0) contains supplementary material, which is available to authorized users.

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Background: Data on SARS-CoV-2 transmission among children living with healthcare workers (HCWs) are scarce. Methods: A cross-sectional study was performed at a tertiary Hospital in Madrid, including children of HCW who suffered from SARS-CoV-2 infection between March and May 2020. Children underwent enzyme-linked immunosorbent serological study for detecting SARS-CoV-2 antibodies: VIRCELL IgG assay. Results: One hundred thirteen children from 69 HCWs with confirmed SARS-CoV-2 infection were recruited: 47 children had positive IgG (41.6%). Children secondary attack rate was 43.7% (25% if both parents have had asymptomatic infection; 39.5% if one parent was symptomatic; and 47% when both parents had symptoms). Having a positive sibling was associated with a positive IgG result (odds ratio = 12.2; 95% confidence interval: 4.4-33.7, P < 0.001). Median age was higher in IgG positive children (P = 0.022). Children who referred anosmia presented higher IgG titles (P < 0.04). Conclusions: We observed a very high SARS-CoV-2 transmission in children of HCW during the first pandemic wave, especially when both parents were symptomatic. Having a positive sibling was associated with seroconversion, supporting the important role of family clusters in the transmission of SARS-CoV-2.