Cross-sectional prevalence of SARS-CoV-2 antibodies in healthcare workers in paediatric facilities in eight countries.

BACKGROUND: Healthcare workers (HCWs) have been disproportionately affected by coronavirus disease 2019 (COVID-19), which may be driven, in part, by nosocomial exposure. If HCW exposure is predominantly nosocomial, HCWs in paediatric facilities, where few patients are admitted with COVID-19, may lack antibodies to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and be at increased risk during the current resurgence. AIM: To compare the seroprevalence of SARS-CoV-2 amongst HCWs in paediatric facilities in seven European countries and South Africa (N=8). METHODS: All categories of paediatric HCWs were invited to participate in the study, irrespective of previous symptoms. A single blood sample was taken and data about previous symptoms were documented. Serum was shipped to a central laboratory in London where SARS-CoV-2 immunoglobulin G was measured. FINDINGS: In total, 4114 HCWs were recruited between 1st May and mid-July 2020. The range of seroprevalence was 0-16.93%. The highest seroprevalence was found in London (16.93%), followed by Cape Town, South Africa (10.36%). There were no positive HCWs in the Austrian, Estonian and Latvian cohorts; 2/300 [0.66%, 95% confidence interval (CI) 0.18-2.4] HCWs tested positive in Lithuania; 1/124 (0.81%, 95% CI 0.14-4.3) HCWs tested positive in Romania; and 1/76 (1.3%, 95% CI 0.23-7.0) HCWs tested positive in Greece. CONCLUSION: Overall seroprevalence amongst paediatric HCWs is similar to their national populations and linked to the national COVID-19 burden. Staff working in paediatric facilities in low-burden countries have very low seroprevalence rates and thus are likely to be susceptible to COVID-19. Their susceptibility to infection may affect their ability to provide care in the face of increasing cases of COVID-19, and this highlights the need for appropriate preventative strategies in paediatric healthcare settings.

Long-lasting hyporesponsivenss induced by the 23-valent pneumococcal polysaccharide vaccine (PPV23) in asplenic patients with ß-thalassemia major.

We have previously shown that multiple vaccinations with 23-valent pneumococcal polysaccharide vaccine (PPV23s) resulted in attenuated antibody responses to subsequent 7-valent conjugate vaccine (PCV7) in asplenic adults with ß-thalassemia major (Orthopoulos et al. Vaccine 2009; 27:350). However, there is evidence that PPV23-induced immune hyporesponsiveness could be overcome with time (Papadatou et al. Clin Infect Dis 2014; 59:862). In the current study we investigate the duration of hyporesponsiveness in the same cohort seven years after the original study vaccinations. Patients received one dose of 13-valent conjugate vaccine (PCV13) and antibody levels were measured before and one month after vaccination. Antibodies increased significantly after vaccination with PCV13, but were lower than post-PCV7 seven years earlier. Lower pre-vaccination antibody levels were associated with more robust response to PCV13. Our findings suggest that PPV23 should be used cautiously in asplenic adults vaccinated with multiple PPV23s in the past. Measurement of anti-pneumococcal antibodies before and after vaccination could be used to optimise timing of vaccinations and certify vaccine immunogenicity in such individuals.