BackgroundWe aimed to estimate the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence and describe its determinants and associated symptoms among unvaccinated healthcare... Show moreBackgroundWe aimed to estimate the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence and describe its determinants and associated symptoms among unvaccinated healthcare workers (HCWs) after the first wave of the pandemic.MethodsHCWs from 13 Dutch hospitals were screened for antibodies against the spike protein of SARS-CoV-2 in June-July 2020 and after three months. Participants completed a retrospective questionnaire on determinants for occupational and community exposure to SARS-CoV-2 and symptoms suggestive of COVID-19 experienced since January 2020. The seroprevalence was calculated per baseline characteristic and symptom at baseline and after follow-up. Adjusted odds ratios (aOR) for seropositivity were determined using logistic regression.ResultsAmong 2328 HCWs, 323 (13.9%) were seropositive at enrolment, 49 of whom (15%) reported no previous symptoms suggestive of COVID-19. During follow-up, only 1% of the tested participants seroconverted. Seroprevalence was higher in younger HCWs compared to the mid-age category (aOR 1.53, 95% CI 1.07–2.18). Nurses (aOR 2.21, 95% CI 1.34–3.64) and administrative staff (aOR 1.87, 95% CI 1.02–3.43) had a higher seroprevalence than physicians. The highest seroprevalence was observed in HCWs in the emergency department (ED) (aOR 1.79, 95% CI 1.10–2.91), the lowest in HCWs in the intensive, high, or medium care units (aOR 0.47, 95% CI 0.31–0.71). Chronic respiratory disease, smoking, and having a dog were independently associated with a lower seroprevalence, while HCWs with diabetes mellitus had a higher seroprevalence. In a multivariable model containing all self-reported symptoms since January 2020, altered smell and taste, fever, general malaise/fatigue, and muscle aches were positively associated with developing antibodies, while sore throat and chills were negatively associated.ConclusionsThe SARS-CoV-2 seroprevalence in unvaccinated HCWs of 13 Dutch hospitals was 14% in June-July 2020 and remained stable after three months. A higher seroprevalence was observed in the ED and among nurses, administrative and young staff, and those with diabetes mellitus, while a lower seroprevalence was found in HCWs in intensive, high, or medium care, and those with self-reported lung disease, smokers, and dog owners. A history of altered smell or taste, fever, muscle aches and fatigue were independently associated with the presence of SARS-CoV-2 antibodies in unvaccinated HCWs. Show less
This thesis contains a variety of information about the natural and vaccine induced immunity against the human papillomavirus. The spontaneously induced HPV-specific humoral response after... Show moreThis thesis contains a variety of information about the natural and vaccine induced immunity against the human papillomavirus. The spontaneously induced HPV-specific humoral response after infection was assessed in population-based studies. The vaccine-induced changes in HPV-seroprevalence among the HPV unvaccinated Dutch population aged 0-89 years, where we compared the HPV-seroprevalence before the introduction of the HPV vaccine with data of approximately six years post-implementation of the national HPV vaccination program. Also, the HPV immune status of the Dutch Caribbean population just after introduction of HPV vaccination was determined. Moreover, the longitudinal relation between the hr-HPV antibody levels and the prevalence of HPV infections in three-dose vaccinated girls were studied. And more insight was gained into humoral and cellular immune responses after just a one-dose of the HPV vaccine. At last, the kinetics of innate and adaptive immune responses directly after vaccination different HPV vaccines were investigated. In the coming years some important changes are expected regarding HPV screening and vaccination. The effectiveness of the one-dose schedule will become clear as clinical trials end. In the Netherlands, a sex-neutral vaccination will be implemented soon. These changes will need to be monitored to provide scientific answers about the effectiveness and immunogenicity. Show less
Korndewal, M.J.; Mollema, L.; Tcherniaeva, I.; Klis, F. van der; Kroes, A.C.M.; Oudesluys-Murphy, A.M.; ... ; Melker, H.E. de 2015
