ABSTRACT
Background: While a COVID-19 vaccine protects people from serious illness and death, it remains concern when and how to relax from the high cost strict non-pharmaceutical interventions (NPIs). Methods We developed a stochastic calculus model to identify the level of vaccine coverage that would allow safe relaxation of NPIs, and the vaccination strategies that can best achieve this level of coverage. We applied Monto Carlo simulations more than 10,000 times to remove random fluctuation effects and obtain fitted/predicted epidemic curve based on various parameters with 95% confidence interval (95% CI) at each time point. Results We found that a vaccination coverage of 50.42% was needed for the safe relaxation of NPIs, if the vaccine effectiveness was 79.34%. However, with the increasing of variants transmissibility and the decline of vaccine effectiveness for variants, the threshold for lifting NPIs would be higher. We estimated that more than 8 months were needed to achieve the vaccine coverage threshold in the combination of accelerated vaccination strategy and key groups firstly strategy. Conclusion If there are sufficient doses of vaccine then an accelerated vaccination strategy should be used, and if vaccine supply is insufficient then high-risk groups should be targeted for vaccination first. Sensitivity analyses results shown that the higher the transmission rate of the virus and the lower annual vaccine supply, the more difficult the epidemic could be under control. In conclusion, as vaccine coverage improves, the NPIs can be gradually relaxed. Until that threshold is reached, however, strict NPIs are still needed to contain the epidemic. The more transmissible SARS-CoV-2 variant lead to higher resurgence probability, which indicates the importance of accelerated vaccination and achieving the vaccine coverage earlier. Trial registration We did not involve clinical trial.
Subject(s)
COVID-19 , Chronic DiseaseABSTRACT
Background: It is important to improve vaccination strategies and immunization programs to achieve herd immunity to infectious diseases, particularly in general community-dwelling populations. Methods To assess the acceptance of COVID-19 vaccination, we conducted face-to-face surveys and online surveys in Shanghai, Zhejiang, and Qinghai province. A fixed effects model and a random effects model were used to analyze factors associated with acceptance of COVID-19 vaccination. Findings The results indicated that 82·6% of participants (77·0% in Shanghai and 87·3% in Zhejiang) were willing to receive vaccination when it was available in the community, and 57·2% of deliverymen, 43·3% of medical workers, 78·2% of parents of primary and secondary school children, and 72·2% of parents of preschool children were willing to receive vaccination. The models showed that participants who were male, 60 to 69 years-old, from rural areas, had less education, had good health status, and had positive attitudes and trust in vaccines approved by National Health Commission were more likely to accept vaccination. Participants also had increased vaccination acceptance if it was recommended by government sources, doctors, relatives, or friends. Most participants learned about COVID-19 vaccination from television, radio, and newspapers, followed by community or hospital campaigns and the internet. Those who did not want to receive vaccination were mainly concerned about safety (288, 59·6%) and efficacy (196, 40·6%). Conclusions Government sources and doctors could increase acceptance of vaccination by promoting the efficacy and safety of COVID-19 vaccination by use of mass media and emphasizing the necessity of vaccination for everyone.
Subject(s)
COVID-19 , Communicable DiseasesABSTRACT
The Coronavirus (COVID-19) epidemic, which was first reported in December 2019 in Wuhan, China, has caused 3,314 death as of March 31, 2020 in China. This study aimed to investigate the spatial associations of daily particulate matter (PM) concentrations with death rate of COVID-19 in China. We conducted a cross-sectional analysis to examine the spatial associations of daily PM2.5 and PM10 concentrations with death rate of COVID-19 in China through multiple linear regression method. We found that COVID-19 held higher death rates with increasing concentration of PM2.5 and PM10 levels in the spatial scale, which may affect the process of patients developed from mild to severe and finally influence the prognosis of COVID-19 patients.
Subject(s)
COVID-19ABSTRACT
Background: Since its first cases occurrence in Wuhan, China, the Coronavirus Disease 2019 (COVID-19) has been spreading rapidly to other provinces and neighboring countries. A series of intervention strategies have been implemented, but didn't stop its spread. Methods: Two mathematical models have been developed to simulate the current epidemic situation in the city of Wuhan and in other parts of China. Special considerations were given to the mobility of people for the estimation and forecast the number of asymptomatic infections, symptomatic infections, and the infections of super-spreading events (Isse). Findings: The basic reproductive number (R0) was calculated for the period between 18 January 2020 and 16 February 2020: R0 declined from 5.75 to 1.69 in Wuhan and from 6.22 to 1.67 in the entire country (not including the Wuhan area). At the same time, Wuhan is estimated to observe a peak in the number of confirmed cases around 6 February 2020. The number of infected individuals in the entire country (not including the Wuhan area) peaked around February 3. The results also show that the peak of new asymptomatic cases per day in Wuhan occurred on February 6, and the peak of new symptomatic infections have occurred on February 3. Concurrently, while the number of confirmed cases nationwide would continue to decline, the number of real-time COVID-19 inpatients in Wuhan has reached a peak of 13,030 on February 14 before it decreases. The model further shows that the COVID-19 cases will gradually wane by the end of April 2020, both in Wuhan and the other parts of China. The number of confirmed cases would reach the single digit on March 27 in Wuhan and March 19 in the entire country. The five cities with top risk index in China with the exclusion of Wuhan are: Huanggang, Xiaogan, Jingzhou, Chongqing, and Xiangyang city. Interpretations: Although the national peak time has been reached, a significant proportion of asymptomatic patients and the infections of super-spreading events (Isse) still exist in the population, indicating the potential difficulty for the prevention and control of the disease. As the Return-to-Work tide is approaching and upgrading, further measures (e.g., escalatory quarantine, mask wearing when going out, and sit apart when taking vehicles) will be particularly crucial to stop the COVID-19 in other cities outside of Wuhan.