Coronavirus (COVID-19) Collection
- With the world in a race to vaccinate as many people as possible, concerns about vaccine efficacy have continued to arise, particularly related to variants of concern (VoC). The latest variant to be upgraded to a VoC was first discovered in India: B.1.617. This variant has three different subtypes including Delta or B.1.617.2, which has become the most reported lineage in India and has been responsible for a devastating second wave of infection in the country (Outbreak.info, 2021). This variant is defined by seven mutations in the spike protein, two of which – L452R and T478K – are suspected to increase transmissibility (Adam, 2021).
- In many countries that managed to contain the earlier COVID-19 outbreaks through extensive social distancing or a large-scale lock-down, a second or third wave of the outbreak took place. Although a lock-down or strict social distancing seem to be effective in containing the epidemic, these come with very high socioeconomic costs. The contact tracing strategy of “Diagnose, Trace, Isolate” has been highlighted as a more sustainable alternative in addition to personal hygiene measures such as wearing masks and washing hands (Rajan et al., 2020; World Health Organization, 2020a).
- Contact tracing plays a key role in controlling communicable diseases by seeking to break the chain of transmission between individuals. It is recommended by the World Health Organization (WHO) as part of the global strategy for coronavirus disease 2019 (COVID-19), which also includes case identification, isolation, testing, care, and quarantine (World Health Organization, 2020). Contact tracing consists of identifying and monitoring individuals who have been in close contact with an infected person (Public Health Ontario, 2021).
- The early estimate of asymptomatic ratio has been reported as ranging from 8 to 54% (Nishiura et al., 2020). Besides, more than half of secondary transmissions with coronavirus disease 2019 (COVID-19) are considered to occur from asymptomatically infected people (Johansson et al., 2021). The estimate reflects the substantial number of secondary transmissions from pre-symptomatic individuals who eventually develop illness.
- In the week before October 27, 2020, an exponential increase in the number of new weekly coronavirus disease-19 (COVID-19) cases was reported worldwide, with over 2.8 million new cases and approximately 40 000 deaths (WHO, 2020). As of October 27, a cumulative total of >42 million COVID-19 cases and 1.1 million deaths had been reported worldwide (WHO, 2020); among these, a total of 22 364 cases and 460 deaths were reported in South Korea (Korea Disease Control and Prevention Agency, 2020). During the initial COVID-19 epidemic phase in South Korea from February to March 2020, a massive outbreak in Daegu accounted for the majority of cases, whereas cases in the Seoul metropolitan area were not prominent, despite outbreaks at the Guro-gu customer service call center and Itaewon night clubs (Jung et al., 2020; Park et al., 2020).
- Coronavirus disease 2019 (COVID-19) has spread rapidly across the world. Tunisia reacted early to COVID-19, resulting in a low number of infections during the first wave of the pandemic. This study was performed to model the effects of different interventions on the evolution of cases and to compare these with the Tunisian experience.
- As of September 21, 2020, over 30.6 million coronavirus disease 2019 (COVID-19) cases and 950,000 deaths have been reported globally (World Health Organization, 2020a) Case detection and contact tracing were essential components to control the spread of COVID-19. Taiwan government has enhanced notifiable disease reporting and laboratory surveillance since January 2020 by testing the respiratory specimens from various sources for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), including patients who were reported as cases of severe or novel influenza infection, clusters of upper respiratory disease/fever of unknown origin, and patients with respiratory infections via the sentinel surveillance.
- The serial interval of an infectious disease, also known as the generation time, is defined as the time between analogous phases in successive cases of a chain of infection (Porta, 2016). The transmission interval, or the time between the infection events of the infector and the infectee, is a particularly crucial serial interval as it determines how rapidly a disease can spread in the community (Fine, 2003) and provides a time window for its containment. This interval, however, is difficult to measure, as times of infection are often unknown.
- Hong Kong Special Administrative Region, with a population of 7.4 million, is a major financial and transport hub located at the southern coast of China and has intimate ties with mainland China and the rest of the world. Having experienced the severe acute respiratory syndrome (SARS) outbreak in 2003, Hong Kong closely monitored the situation of coronavirus disease 2019 (COVID-19) following the first report in Wuhan on 31 December 2019. In early January 2020, COVID-19 was included as a statutory notifiable disease.