Dr. Rebecca Müller (Mannheim/ DE), Michael Hetjens (Mannheim/ DE), Dr. Svetlana Hetjens (Mannheim/ DE), Prof. Dr. Michael Schmidt (Mannheim/ DE), Prof. Dr. Harald Klüter (Mannheim/ DE), Prof. Dr. Patrick Wuchter (Mannheim/ DE)
Background
(Re-)Infections of pre-immunized vaccinated or convalescent individuals were the main players in SARS-CoV-2 infection waves with the different omicron strains. There is still a lack of detailed data on how different immunization schemes, exposition risks and antibody tests could predict the probability of (re-)infection. This population-based approach aims to understand the underlying mechanisms of infection and immunization, which is relevant for any future pandemic.
Methods
To address this issue we selected blood donors who donated blood in June or July 2022 at the beginning of the omicron BA.5 wave. We sent a digital COVID-19 REDCap survey including 170 data fields on SARS-CoV-2 exposure, previous immunizations, and acute infection in the timespan between July and October 2022 to these donors. In close collaboration with data protection supervisors, we thoroughly planned the digital study information and consent forms and permission was granted by the local Ethics committee. Statistical analyses of survey data were performed via "SAS" and "Prism".
Results
Of 52.512 blood donors invited for study participation via E-mail, 20% completed the questionnaire. Thus, we recruited a cohort of 10.532 individuals for the investigation of detailed anamnestic data. Analysis revealed that full vaccination with monovalent vaccines significantly reduced infection rates with non-Omicron variants and still had effects on infections with Omicron strains before BA.5 but did not significantly reduce infection rates with the BA.5 strain compared with not fully vaccinated individuals. Carefully partitioned subgroup analysis showed that various combinations of vaccinations and previously experienced infections with different SARS-CoV-2 strains led to significantly varying infections rates during the BA.5 wave.
Conclusion
REDCap database approach is a suitable method for digital clinical research including anamnestic and serological data. Study concepts based on digital consent forms and questionnaires are convenient for study participants and lead to high response rates. As many countries recently reduced their SARS-CoV-2 surveillance systems and as monitoring does not cover self-testing, digital surveys are a helpful way to capture reliable data on (re-)infection rates keeping evidence up to date.
Offenlegung Interessenkonflikt:
The authors declare no conflict of interest.