Reasons for SARS-CoV-2 infection in children and their role in the transmission of infection according to age: a case-control study.

BACKGROUND: The locations where children get exposed to SARS-CoV-2 infection and their contribution in spreading the infection are still not fully understood. Aim of the article is to verify the most frequent reasons for SARS-CoV-2 infection in children and their role in the secondary transmission of the infection. METHODS: A case-control study was performed in all SARS-CoV-2 positive children (n = 81) and an equal number of age- and sex- matched controls who were referred to the S. Camillo-Forlanini Pediatric Walk-in Center of Rome. The results of all SARS-CoV-2 nasopharyngeal swabs performed in children aged < 18 years from October 16 to December 19, 2020 were analyzed. RESULTS: School contacts were more frequent in controls than in cases (OR 0.49; 95% CI: 0.3-0.9), while household contacts were higher in cases (OR 5.09; 95% CI: 2.2-12.0). In both cases and controls, school contacts were significantly less frequent, while on the contrary household contacts seemed to be more frequent in nursery school children compared to primary school or middle/high school children. A multivariate logistic regression showed that the probability of being positive to SARS-CoV-2 was significantly lower in children who had school contacts or who had flu symptoms compared to children who had household contacts. Results showed a 30.6% secondary attack rate for household contacts. CONCLUSION: In our study population, the two most frequent reasons for SARS-CoV-2 infection were school and home contacts. The risk of being positive was 5 times lower in children who had school contacts than in children who had household contacts.

Longitudinal dynamics of SARS-CoV-2 anti-receptor binding domain IgG antibodies in a wide population of health care workers after BNT162b2 vaccination.

OBJECTIVES: With the availability of vaccines, commercial assays detecting anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies evolved toward quantitative assays directed to the spike glycoprotein or its receptor-binding domain (RBD). The objective was to perform a large-scale, longitudinal study involving health care workers (HCWs), with the aim of establishing the kinetics of immune response throughout the 9-month period after receipt of the second dose of the BNT162b2 vaccine. METHODS: Quantitative determination of immunoglobulin (Ig) G antibodies against the RBD of the S1 subunit of the spike protein of SARS-CoV-2 on the Alinity systems. RESULTS: The highest levels of anti-RBD IgG were measured after 1 month from full vaccination (median: 1432 binding antibody units/ml [BAU/ml]); subsequently, a steep decrease (7.4-fold decrease) in IgG levels was observed at 6 months (median: 194.3 BAU/ml), with a further 2.5-fold decrease at 9 months (median: 79.3 BAU/ml). Furthermore, the same data, when analyzed for sex, showed significant differences between male and female participants at both 1 and 9 months from vaccination, but not at 6 months. CONCLUSION: Our results confirm the tendency of anti-RBD antibodies to decrease over time, also when extending the analysis up to 9 months, and highlight a better ability of the female sex to produce antibodies 1 month and 9 months after vaccination. Overall, these data, obtained in a wide population of HCWs, support the importance of having increased the vaccine doses.

Serological response to COVID-19 vaccination in patients with cancer older than 80 years.

Central studies carried out on vaccines against the severe acute respiratory syndrome coronavirus 2 (SARS-COV2) excluded patients receiving immunosuppressive therapy and those diagnosed with an immunosuppressive condition. Moreover, there are no data on vaccine efficacy regarding older patients with cancer. OBJECTIVES: The primary objective was to evaluate the seroprevalence of the SARS-CoV2 IgG in older patients (aged ≥80 years) diagnosed with solid or hematological malignancies, one month after administering the second dose of the BNT162b2 vaccine. MATERIALS AND METHODS: We screened 74 older patients with cancer, 45 of them accepted to receive the vaccination and collected serum samples from 36 patients; a group of medical doctors and nurses from our hospital was used as a control in a 1:2 ratio. RESULTS: The median age was 82 years (range 80-89). Median serum IgG were 2396,10 AU/ml (range 0-32,763,00) in patients with cancer and 8737,49 AU/ml (398.90-976,280,00) in the control group, p < 0.0001. Additional subgroup analyses were performed comparing males and females, patients treated with chemotherapy versus other therapies (immunotherapy, targeted therapy), solid tumors versus hematological malignancies, early (I-II) versus advanced (III-IV) stage of disease, continuative corticosteroid use or not. None of them reached statistical significance. CONCLUSION: Our study shows for the first time that patients with cancer aged ≥80 years can have a serological response to the BNT162b2 COVID-19 vaccine one month after vaccination and consequently support the vaccination campaign currently underway in this frail population.