ABSTRACT
Understanding SARS-CoV-2 breakthrough infections in vaccinated healthcare workers is of key importance in mitigating the effects of the COVID-19 pandemic in healthcare facilities. An observational prospective cohort study was conducted in vaccinated employees with acute SARS-CoV-2 infection between October 2021 and February 2022. Serological and molecular testing was performed to determine SARS-CoV-2 viral load, lineage, antibody levels, and neutralizing antibody titers. A total of 571 (9.7%) employees experienced SARS-CoV-2 breakthrough infections during the enrolment period, of which 81 were included. The majority (n = 79, 97.5%) were symptomatic and most (n = 75, 92.6%) showed Ct values < 30 in RT-PCR assays. Twenty-four (30%) remained PCR-positive for > 15 days. Neutralizing antibody titers were strongest for the wildtype, intermediate for Delta, and lowest for Omicron variants. Omicron infections occurred at higher anti-RBD-IgG serum levels (p = 0.00001) and showed a trend for higher viral loads (p = 0.14, median Ct difference 4.3, 95% CI [-2.5-10.5]). For both variants, viral loads were significantly higher in participants with lower anti-RBD-IgG serum levels (p = 0.02). In conclusion, while the clinical course of infection with both the Omicron and Delta variants was predominantly mild to moderate in our study population, waning immune response over time and prolonged viral shedding were observed.
ABSTRACT
[This corrects the article DOI: 10.1371/journal.pone.0246312.].
ABSTRACT
OBJECTIVE: Understanding mild to moderate symptoms of coronavirus disease 2019 (Covid-19) is important in order to identify active cases early and thus counteract transmission. METHODS: In March 2020, Leipzig University Hospital established an outpatient clinic for patients potentially infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Confirmed cases with mild to moderate symptoms self-isolated at home and were followed-up by daily telephone calls for at least 14 days. Symptoms and course of illness of these patients are reported here. RESULTS: From March 20 to April 17, 2020, 1460 individuals were tested for SARS-CoV-2 by naso- or oropharyngeal swab for real-time polymerase chain reaction (RT-PCR). Covid-19 was confirmed in 91 (6.2%) patients, of which 87 were included in the final analysis. Patients presented for testing after a mean of 5.9 days (IQR = 2.0-8.5). The median age was 37.0 years (IQR = 28.5-53), and 48 (55.2%) were female. Five (5.7%) patients required hospital admission during the course of illness. Most frequently reported symptoms were fatigue (n = 64, 74%), cough (n = 58, 67%), and hyposmia/hypogeusia (n = 44, 51%). In contrast to previous reports, fever occurred in less than a third of patients (n = 25, 29%). By day 14, more than half of the patients had recovered completely (n = 37/70, 52.9%). CONCLUSIONS: Fever seems to be less common in patients of relatively young age diagnosed with mild to moderate Covid-19. This suggests that body temperature alone may be an insufficient indicator of SARS-CoV-2 infection.