Characteristics and outcomes of COVID-19 patients during B.1.1.529 (Omicron) dominance compared to B.1.617.2 (Delta) in 89 German hospitals (preprint)

Background: The SARS-CoV-2 variant of concern B.1.1.529 (Omicron) was first described in November 2021 and soon became the dominant variant worldwide. Existing data suggests a reduced disease severity in comparison to B.1.617.2 (Delta). Differences in characteristics and in-hospital outcomes of patients with COVID-19 in Germany during the Omicron period compared to Delta are not thoroughly studied. Surveillance for severe acute respiratory infections (SARI) represents an integral part of infectious disease control in Germany. Methods: Administrative data from 89 German Helios hospitals was retrospectively analysed. Laboratory-confirmed SARS-CoV-2 infections were identified by ICD-10-code U07.1 and SARI cases by ICD-10-codes J09-J22. COVID-19 cases were stratified by concomitant SARI. A nine-week observational period between December 6, 2021 and February 6, 2022 was defined and divided into three phases with respect to the dominating virus variant (Delta, Delta to Omicron transition, Omicron). Regression analyses adjusted for age, gender and Elixhauser comorbidities were applied to assess in-hospital patient outcomes. Results: A total cohort of 4,494 inpatients was analysed. Patients in the Omicron dominance period were younger (mean age 61.6 vs. 47.8; p<0.01), more likely to be female (54.7% vs. 47.5%; p<0.01) and characterized by a lower comorbidity burden (mean Elixhauser comorbidity index 8.2 vs. 5.4; p<0.01). Comparing Delta and Omicron periods, patients were at significantly lower risk for intensive care treatment (adjusted odds ratio 0.64 [0.51-0.8]; p<0.001), mechanical ventilation (adjusted odds ratio 0.38 [0.28-0.51]; p<0.001), and in-hospital mortality (adjusted odds ratio 0.42 [0.32-0.56]; p<0.001). This also applied to the separate COVID-SARI group. During the Delta to Omicron transition, case numbers of COVID-19 without SARI exceeded COVID-SARI. Conclusion: Patient characteristics and outcomes differ during the Omicron dominance period as compared to Delta suggesting a reduced disease severity with Omicron infections. SARI surveillance might play a crucial role in assessing disease severity of future SARS-CoV-2 variants.

Effect of Gender, Age and Vaccine on Reactogenicity and Incapacity to Work after COVID-19 Vaccination: A Survey among Health Care Workers (preprint)

Background: The aim of our study was to assess the influence of gender and age on reactogenicity by the different vaccines and their combinations. Further parameters were the reduction in working capacity after vaccination and the influence of the time of day when vaccines were administered. Methods We conducted a survey on COVID-19 vaccinations and eventual reactions among employees of 89 hospitals of the Helios Group. On May 19th, 2021 employees received an invitation by e-mail from the chief medical officer with a link to the survey tool. Participation was voluntary and non-traceable. The survey was closed on June 21st, 2021. Results 8,375 participants reported on 16,727 vaccinations. Reactogenicity was reported in 75% of COVID-19 vaccinations. In 23% the capacity to work was affected. Major risk factors were female gender, younger age and vaccine other than BNT162b2. ChAdOx induced impairing reactogenicity mainly after the prime vaccination (70.5%), while mRNA-1273 led to more pronounced reactions after the second dose (71.7%). Heterologous prime-booster vaccinations with ChAdOx followed by either mRNA-1273 or BNT162b2 were associated with the highest risk for impairment (81.4%). The time of day of the vaccinations showed no influence. Conclusions Young women had the highest chance to experience reactogenicity and to be unable to work after COVID-19 vaccination. When vaccinating a large part of a workforce, especially in professions with a higher proportion of women like health care, employers as well as employees must be prepared for a noticeable amount of absenteeism. Trial registration The study was approved by the Ethic Committee of the Aerztekammer Berlin on May 27th, 2021 (Eth-37/21) and registered in the German Clinical Trials Register (DRKS 00025745). The study was supported by the Helios research grant HCRI-ID 2021-0272.