The rapid and efficient strategy for SARS-CoV-2 Omicron transmission control: analysis of outbreaks at the city level

Clinical outcomes of Omicron infection and vaccine acceptance among pediatric liver transplant recipients: insights from a cross-sectional survey

OBJECTIVES

Our study aims to explore the clinical characteristics of Omicron infection in pediatric liver transplant recipients (PLTRs), after the national COVID-19 outbreak. Additionally, we will investigate changes in vaccine coverage and parental attitudes towards vaccinating their children after this current outbreak.

METHODS

We conducted a web-based questionnaire survey to gather information on Omicron infection, vaccination status, and guardian attitude among PLTRs. Besides, utilized valid questionnaire and long-term follow-up information processing techniques, and performed statistical analysis of relevant parameters.

RESULTS

528 valid questionnaires were collected, among which, 251 responses replied Omicron infection status. The Omicron infection rate in Chinese PLTRs was 56.2% (141/251), similar to the report in the normal population (around 60%). 99.3% of infected PLTRs presented mild symptoms, mostly with fever (78.0%), followed by Cough (76.6%), with a mean RTPCR conversion time of 7 days; the overall PLTRs' vaccination rate in this study was 13.3%, similar to that of our previous study (9.4%). Besides, we found no significant differences of either infection rate or clinical symptoms between the vaccinated and unvaccinated groups. Moreover, the study showed 61.6% of guardians supported COVID-19 inoculation despite the outbreak of Omicron status.

CONCLUSIONS

The symptoms of Omicron infection in Chinese PLTRs were relatively mild, vaccine immunization had a limited effect on PLTRs' defense against Omicron infection, besides, their guardians supported the inoculation policy with a caution.

CLINICAL TRIAL REGISTRATION

http://www.chictr.org.cn , identifier ChiCTR2200055968.

A Regional-Scale Assessment-Based SARS-CoV-2 Variants Control Modeling with Implications for Infection Risk Characterization

Background

The emergence and progression of highly divergent SARS-CoV-2 variants have posed increased risks to global public health, triggering the significant impacts on countermeasures since 2020. However, in addition to vaccination, the effectiveness of non-pharmaceutical interventions, such as social distancing, masking, or hand washing, on different variants of concern (VOC) remains largely unknown.

Objective

This study provides a mechanistic approach by implementing a control measure model and a risk assessment framework to quantify the impacts of control measure combinations on the transmissions of five VOC (Alpha, Beta, Delta, Gamma, and Omicron), along with a different perspective of risk assessment application.

Materials and Methods

We applied uncontrollable ratios as an indicator by adopting basic reproduction number (R 0) data collected from a regional-scale survey. A risk assessment strategy was established by constructing VOC-specific dose-response profiles to implicate practical uses in risk characterization when exposure data are available.

Results

We found that social distancing alone was ineffective without vaccination in almost all countries and VOC when the median R 0 was greater than two. Our results indicated that Omicron could not be contained, even when all control measure combinations were applied, due to its low threshold of infectivity (~3×10-4 plague-forming unit (PFU) mL-1).

Conclusion

To facilitate better decision-making in future interventions, we provide a comprehensive evaluation of how combined control measures impact on different countries and various VOC. Our findings indicate the potential application of threshold estimates of infectivity in the context of risk communication and policymaking for controlling future emerging SARS-CoV-2 variant infections.

An AI-empowered indoor digital contact tracing system for COVID-19 outbreaks in residential care homes

An AI-empowered indoor digital contact-tracing system was developed using a centralized architecture and advanced low-energy Bluetooth technologies for indoor positioning, with careful preservation of privacy and data security. We analyzed the contact pattern data from two RCHs and investigated a COVID-19 outbreak in one study site. To evaluate the effectiveness of the system in containing outbreaks with minimal contacts under quarantine, a simulation study was conducted to compare the impact of different quarantine strategies on outbreak containment within RCHs. The significant difference in contact hours between weekdays and weekends was observed for some pairs of RCH residents and staff during the two-week data collection period. No significant difference between secondary cases and uninfected contacts was observed in a COVID-19 outbreak in terms of their demographics and contact patterns. Simulation results based on the collected contact data indicated that a threshold of accumulative contact hours one or two days prior to diagnosis of the index case could dramatically increase the efficiency of outbreak containment within RCHs by targeted isolation of the close contacts. This study demonstrated the feasibility and efficiency of employing an AI-empowered system in indoor digital contact tracing of outbreaks in RCHs in the post-pandemic era.

Comparative epidemiology of outbreaks caused by SARS-CoV-2 Delta and Omicron variants in China

From 2020 to December 2022, China implemented strict measures to contain the spread of severe acute respiratory syndrome coronavirus 2. However, despite these efforts, sustained outbreaks of the Omicron variants occurred in 2022. We extracted COVID-19 case numbers from May 2021 to October 2022 to identify outbreaks of the Delta and Omicron variants in all provinces of mainland China. We found that omicron outbreaks were more frequent (4.3 vs. 1.6 outbreaks per month) and longer-lasting (mean duration: 13 vs. 4 weeks per outbreak) than Delta outbreaks, resulting in a total of 865,100 cases, of which 85% were asymptomatic. Despite the average Government Response Index being 12% higher (95% confidence interval (CI): 9%, 15%) in Omicron outbreaks, the average daily effective reproduction number (Rt) was 0.45 higher (95% CI: 0.38, 0.52, p < 0.001) than in Delta outbreaks. Omicron outbreaks were suppressed in 32 days on average (95% CI: 26, 39), which was substantially longer than Delta outbreaks (14 days; 95% CI: 11, 19; p = 0.004). We concluded that control measures effective against Delta could not contain Omicron outbreaks in China. This highlights the need for continuous evaluation of new variants' epidemiology to inform COVID-19 response decisions.

Efficacy of traditional Chinese medicine on shortening the negative conversion time of SARS-CoV-2 ribonucleic acid in patients with mild COVID-19: a retrospective cohort study

Background

The holistic view of the 'The unity of man and nature' promotes the development and application of traditional Chinese medicine (TCM). Despite the absence of modern pharmacological therapies with robust efficacy against coronavirus disease 2019 (COVID-19), TCM has exhibited potential utility for treating the disease in clinical practice.

Methods

A retrospective cohort study was conducted to investigate the therapeutic effect of TCM treatment intensity (TCMTI) in patients with mild COVID-19. A total of 6120 laboratory-confirmed patients with mild COVID-19 were recruited from temporary isolation facilities. The primary outcome measure was severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) ribonucleic acid conversion time. In addition, restricted cubic spline models were employed to elucidate nonlinear relationships.

Results

The median age (range) of the study participants was 43.0 (2.0-75.0) years, with a median hospitalization duration of 9.7 (4.1-22.5) days. The median time for achieving SARS-CoV-2 ribonucleic acid negativity was 6.67 days. The restricted cubic spline models revealed a remarkable nonlinear association between TCMTI and the time-to-ribonucleic acid negativity. After adjusting for potential confounders, the high TCMTI group exhibited a markedly shorter median time to SARS-CoV-2 ribonucleic acid negativity and reduced hospitalization duration (P < 0.001) than the low TCMTI group. Moreover, the mean time to achieve SARS-CoV-2 ribonucleic acid negativity was shortened by 1.909 days (P < 0.001) in the high-TCMTI group compared to the low-TCMTI group.

Conclusion

This study suggests that early initiation and intensified use of TCM may accelerate the time required to achieve SARS-CoV-2 ribonucleic acid negativity in patients with COVID-19, bearing considerable implications for public health.

Correlation of SARS-CoV-2 RNA and nucleocapsid concentrations in samples used in INSTAND external quality assessment schemes

OBJECTIVE

In routine clinical laboratories, severe acute respiratory syndrome coronavirus (SARS-CoV-2) infection is determined by reverse-transcription PCR (RT-PCR). In the COVID pandemic, a wide range of antigen detection tests were also in high demand. We investigated the correlation between SARS-CoV-2 NCap antigen and N gene concentration by analyzing samples from several INSTAND external quality assessment (EQA) schemes starting in March 2021. The absolute N gene concentration was measured using reverse transcriptase digital PCR (RT-dPCR) as reference value. Moreover, the performance of five commercial ELISA tests using an EQA inactivated SARS-CoV-2 sample at different concentrations was assessed on the basis of these reference values.

RESULTS

Quantitative ELISA and RT-dPCR results showed a good correlation between SARS-CoV-2 NCap antigen and RNA concentration, but this correlation varies among SARS-CoV-2 isolates. A direct correlation between SARS-CoV-2 NCap antigen concentration and genome concentration should not be generally assumed.

CONCLUSION

Further correlation studies between SARS-CoV-2 RNA and NCap antigen concentrations are needed, particularly in clinical samples and for emerging SARS-CoV-2 variants, to support the monitoring and improvement of antigen testing.

Effectiveness of Paxlovid, an Oral Antiviral Drug, Against the Omicron BA.5 Variant in Korea: Severe Progression and Death Between July and November 2022

BACKGROUND

Paxlovid is an oral antiviral drug that received emergency use authorization in South Korea for the treatment of patients with mild-to-moderate coronavirus disease 2019 (COVID-19) on January 14, 2022. Since the onset of the severe acute respiratory syndrome coronavirus 2 pandemic, the virus has continued to evolve. The emergence of new variants has raised concerns about possible reductions in the effectiveness of vaccines and drugs. The effectiveness of Paxlovid in patients infected with the omicron variant and subvariants has not yet been determined. This study assessed the effectiveness of Paxlovid at reducing the risk of severe/critical illness or death and death in patients with mild-to-moderate COVID-19 caused by omicron subvariant BA.5.

METHODS

In this nationwide retrospective cohort study, data on 8,902,726 patients were collected from four sources (the Drug Utilization Review database, COVID-19 Patient Information Management System, confirmed patient information, and basic epidemiological investigation data) between July 1 and November 30, 2022. Multivariable logistic regression analysis was conducted, with adjustment for age, sex, severe acute respiratory syndrome coronavirus 2 immunity (vaccination), and comorbidities.

RESULTS

A total of 1,936,925 patients with COVID-19 were included in the analysis, including 420,996 patients treated with Paxlovid, and 1,515,959 patients not treated with Paxlovid. Paxlovid treatment in patients aged ≥ 60 years of age was associated with significantly reduced risk of severe/critical illness or death (46.0%), and death rate (32.5%), and its effectiveness was high, regardless of vaccination status.

CONCLUSION

Paxlovid is effective at reducing the risk of death due to COVID-19 in patients with omicron BA.5 infection, especially in older patients, regardless of vaccination status. This suggests that older patients with COVID-19-related symptoms should be administered Paxlovid, regardless of their vaccination status, to reduce severity and risk of death.

Reduced SARS-CoV-2 infection risk is associated with the use of Seven-Flavor Herb Tea: A multi-center observational study in Shanghai, China

OBJECTIVE

Omicron, a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant, is responsible for numerous infections in China. This study investigates the association between the use of Seven-Flavor Herb Tea (SFHT) and the risk of SARS-CoV-2 infection to develop precise and differentiated strategies for control of the coronavirus disease 2019 (COVID-19).

METHODS

This case-control study was conducted at shelter hospitals and quarantine hotels in China. A total of 5348 laboratory-confirmed COVID-19 patients were enrolled between April 1 and May 31, 2022, while 2190 uninfected individuals served as healthy controls. Structured questionnaires were used to collect data on demographics, underlying diseases, vaccination status, and use of SFHT. Patients were propensity-score-matched using 1:1 nearest-neighbor matching of the logit of the propensity score. Subsequently, a conditional logistic regression model was used for data analysis.

RESULTS

Overall, 7538 eligible subjects were recruited, with an average age of [45.54 ± 16.94] years. The age of COVID-19 patients was significantly higher than that of uninfected individuals ([48.25 ± 17.48] years vs [38.92 ± 13.41] years; t = 22.437, P < 0.001). A total of 2190 COVID-19 cases were matched with uninfected individuals at a 1:1 ratio. The use of SFHT (odds ratio = 0.753, 95% confidence interval: 0.692, 0.820) was associated with a lower risk of SARS-CoV-2 infection compared to untreated individuals.

CONCLUSION

Our findings suggest that taking SFHT reduces the risk of SARS-CoV-2 infection. This is a useful study in the larger picture of COVID-19 management, but data from large-sample multi-center, randomized clinical trial are warranted to confirm the finding. Please cite this article as: Zhang SX, Chen XX, Zheng Y, Cai BH, Shi W, Ru M, Li H, Zhang DD, Tian Y, Chen YL. Reduced SARS-CoV-2 infection risk is associated with the use of Seven-Flavor Herb Tea: a multi-center observational study in Shanghai, China. J Integr Med. 2023; Epub ahead of print.

The COVID-19 pandemic in China: from dynamic zero-COVID to current policy

On 8 January 2023, after 3 years of pandemic control, China changed its management of COVID-19, applying measures against class B infectious diseases instead of Class A infectious diseases. This signaled the end of the dynamic zero-COVID policy and the reopening of the country. With a population of 1.41 billion, China's reopening policy during the COVID-19 pandemic has been characterized by a scientific, gradual, and cautious approach. Several factors contributed to the reopening policy, including an expansion of healthcare capacity, the widespread promotion and uptake of vaccination, and improved prevention and control mechanisms. According to the latest report from the Chinese Center for Disease Control and Prevention, the number of hospitalized COVID-19 patients in the country reached a peak of 1.625 million on January 5, 2023, and has since continued to decline. As of February 13, the number decreased to 26,000: a reduction of 98.4%. Thanks to the efforts of healthcare workers and society as a whole, the country managed to get through the peak of the epidemic in a stable manner.

Lessons drawn from Shanghai for controlling highly transmissible SARS-CoV-2 variants: insights from a modelling study

BACKGROUND

The continuous emergence of novel SARS-CoV-2 variants with markedly increased transmissibility presents major challenges to the zero-COVID policy in China. It is critical to adjust aspects of the policy about non-pharmaceutical interventions (NPIs) by searching for and implementing more effective ways. We use a mathematical model to mimic the epidemic pattern of the Omicron variant in Shanghai to quantitatively show the control challenges and investigate the feasibility of different control patterns in avoiding other epidemic waves.

METHODS

We initially construct a dynamic model with a core step-by-step release strategy to reveal its role in controlling the spread of COVID-19, including the city-based pattern and the district-based pattern. We used the least squares method and real reported case data to fit the model for Shanghai and its 16 districts, respectively. Optimal control theory was utilized to explore the quantitative and optimal solutions of the time-varying control strength (i.e., contact rate) to suppress the highly transmissible SARS-CoV-2 variants.

RESULTS

The necessary period for reaching the zero-COVID goal can be nearly 4 months, and the final epidemic size was 629,625 (95%CI: [608,049, 651,201]). By adopting the city-based pattern, 7 out of 16 strategies released the NPIs more or earlier than the baseline and ensured a zero-resurgence risk at the average cost of 10 to 129 more cases in June. By adopting the district-based pattern, a regional linked release can allow resumption of social activity to ~ 100% in the boundary-region group about 14 days earlier and allow people to flow between different districts without causing infection resurgence. Optimal solutions of the contact rate were obtained with various testing intensities, and higher diagnosis rate correlated with higher optimal contact rate while the number of daily reported cases remained almost unchanged.

CONCLUSIONS

Shanghai could have been bolder and more flexible in unleashing social activity than they did. The boundary-region group should be relaxed earlier and more attention should be paid to the centre-region group. With a more intensive testing strategy, people could return to normal life as much as possible but still ensure the epidemic was maintained at a relatively low level.