Impact of inactivated vaccines on decrease of viral RNA levels in individuals with the SARS-CoV-2 Omicron (BA.2) variant: A retrospective cohort study in Shanghai, China.

Background: SARS-CoV-2 Omicron (BA.2) has stronger infectivity and more vaccine breakthrough capability than previous variants. Few studies have examined the impact of inactivated vaccines on the decrease of viral RNA levels in individuals with the Omicron variant, based on individuals' continuous daily cycle threshold (Ct) values and associated medical information from the infection to hospital discharge on a large population. Methods: We extracted 39,811 individuals from 174,371 Omicron-infected individuals according to data inclusion and exclusion criteria. We performed the survival data analysis and Generalized Estimating Equation to calculate the adjusted relative risk (aRR) to assess the effect of inactivated vaccines on the decrease of viral RNA levels. Results: Negative conversion was achieved in 54.7 and 94.3% of all infected individuals after one and 2 weeks, respectively. aRRs were shown weak effects on turning negative associated with vaccinations in asymptomatic infections and a little effect in mild diseases. Vaccinations had a protective effect on persistent positivity over 2 and 3 weeks. aRRs, attributed to full and booster vaccinations, were both around 0.7 and had no statistical significance in asymptomatic infections, but were both around 0.6 with statistical significance in mild diseases, respectively. Trends of viral RNA levels among vaccination groups were not significant in asymptomatic infections, but were significant between unvaccinated group and three vaccination groups in mild diseases. Conclusion: Inactivated vaccines accelerate the decrease of viral RNA levels in asymptomatic and mild Omicron-infected individuals. Vaccinated individuals have lower viral RNA levels, faster negative conversion, and fewer persisting positive proportions than unvaccinated individuals. The effects are more evident and significant in mild diseases than in asymptomatic infections.

Dynamics of disease characteristics and viral RNA decay in patients with asymptomatic and mild infections during the Omicron wave in Shanghai, China: A retrospective cohort study.

OBJECTIVES: Asymptomatic infections and mild diseases were more common during the Omicron outbreak in Shanghai, China in 2022. This study aimed to assess the characteristics and viral RNA decay between patients with asymptomatic and mild infections. METHODS: A total of 55,111 patients infected with SARS-CoV-2 who were quarantined in the National Exhibition & Convention Center (Shanghai) Fangcang shelter hospital within 3 days after diagnosis from April 9 to May 23, 2022 were enrolled. The kinetics of cycle threshold (Ct) values of reverse transcription-polymerase chain reaction were assessed. The influencing factors for disease progression and the risk factors for the viral RNA shedding time (VST) were investigated. RESULTS: On admission, 79.6% (43,852/55,111) of the cases were diagnosed with asymptomatic infections, and 20.4% were mild diseases. However, 78.0% of initially asymptomatic subjects developed mild diseases at the follow-up. The final proportion of asymptomatic infections was 17.5%. The median time of symptom onset, the duration of symptoms, and the VST were 2 days, 5 days, and 7 days, respectively. Female, age 19-40 years, underlying comorbidities with hypertension and diabetes, and vaccination were associated with higher risks of progressing to mildly symptomatic infections. In addition, mildly symptomatic infections were found to be associated with prolonged VST compared with asymptomatic infections. However, the kinetics of viral RNA decay and dynamics of Ct values were similar among asymptomatic subjects, patients with asymptomatic-to-mild infection, and patients with mild infection. CONCLUSION: A large proportion of initially diagnosed asymptomatic Omicron infections is in the presymptomatic stage. The Omicron infection has a much shorter incubation period and VST than previous variants. The infectivity of asymptomatic infections and mildly symptomatic infections with Omicron is similar.

Vaccination and Government Stringent Control as Effective Strategies in Preventing SARS-CoV-2 Infections: A Global Perspective.

With the rapid implementation of global vaccination against the coronavirus disease 2019 (COVID-19), the threat posed by the disease has been mitigated, yet it remains a major global public health concern. Few studies have estimated the effects of vaccination and government stringent control measures on the disease transmission from a global perspective. To address this, we collected 216 countries' data on COVID-19 daily reported cases, daily vaccinations, daily government stringency indexes (GSIs), and the human development index (HDI) from the dataset of the World Health Organization (WHO) and the Our World in Data COVID-19 (OWID). We utilized the interrupted time series (ITS) model to examine how the incidence was affected by the vaccination and GSI at continental and country levels from 22 January 2020 to 13 February 2022. We found that the effectiveness of vaccination was better in Europe, North America, and Africa than in Asia, South America, and Oceania. The long-term effects outperformed the short-term effects in most cases. Countries with a high HDI usually had a high vaccination coverage, resulting in better vaccination effects. Nonetheless, some countries with high vaccination coverage did not receive a relatively low incidence due to the weaker GSI. The results suggest that in addition to increasing population vaccination coverage, it is crucial to maintain a certain level of government stringent measures to prevent and control the disease. The strategy is particularly appropriate for countries with low vaccination coverage at present.

Health-Related Quality of Life and Influencing Factors of Pediatric Medical Staff During the COVID-19 Outbreak.

Objective: To evaluate the health-related quality of life (HRQoL) status and explore its associated factors in pediatric medical staff during the COVID-19 epidemic so as to provide fundamental evidence for clinicians and administrators to formulate targeted intervention measures to improve the HRQoL and mental health status in pediatric medical staff during this, and future pandemics. Methods: A cross-sectional study was conducted to investigate the HRQoL of pediatric medical staff. Univariable and multivariable logistic regression were used to analyze the associated factors. Results: A total of 2,997 participants were recruited. Females scored worse than males in terms of emotional functioning (OR = 1.6, 95% CI: 1.2-2.1) and cognitive functioning (OR = 1.4, 95% CI: 1.1-1.8). The respondents aged 30-39 and 40-49 years scored worse in nearly all domains of HRQoL compared health care professionals under 30 years old. Respondents with high education had lower scores in physical functioning (OR = 1.3, 95% CI: 1.0-1.7) and emotional functioning (OR = 1.5, 95% CI: 1.2-1.9). Compared with doctors, nurses had higher scores in all domains except for summary score and worry. The respondents whose working places had not set up pediatric fever clinics and isolated observation areas independently had lower scores in all domains except for worry. The respondents who had ever treated patients with COVID-19 had lower scores in all domains. Conclusion: During the COVID-19 outbreak, the HRQoL of pediatric medical staff decreased. The factors associated with HRQoL can be used to develop intervention to improve HRQoL in pediatric medical staff.