Coronavirus (COVID-19) Collection
Reduction in the infection fatality rate of Omicron variant compared with previous variants in South AfricaThe COVID-19 pandemic has been in effect for nearly two years since 2019. According to the World Health Organization (WHO), there have been over 260 million cases including more than 5 million deaths reported (https://www.who.int/emergencies/diseases/novel-coronavirus-2019 2021). The SARS-CoV-2 virus, first identified in late 2019, has mutated multiple times, and its variants have been classified by the WHO into three categories: variants of concern (VOC), variants of interest, and variants under monitoring.
Exported cases were infected on the way: A conjecture derived from analysis on Hong Kong monthly exported COVID-19 casesDuring this COVID-19 pandemic, imported cases have played the role of triggering outbreaks in their arrival city and exported cases are used to infer the infection risk in their departure city (Imai et al., 2020; Menkir et al., 2021). Hong Kong, as a hub of international travel, faced this situation in particular. However, we argue that in the current phase of the pandemic, the role of exported cases in inferring the infection risk in their departure city loses its power; we use Hong Kong, an international travel hub, as an example.
COVID-19 and Lassa fever in Nigeria: A deadly alliance?COVID-19 has become one of the most dangerous pandemics to cause severe problems for humanity in the past decades. SARS-CoV-2, a virus that causes COVID-19, emanated from China in December 2019, when public health officials alerted the World Health Organization (WHO) about pneumonia of an unknown etiology (WHO, 2021; Li et al., 2020). Subsequently, the disease rapidly spread worldwide. Nigeria faces a potential public health crisis owing to the synergistic epidemic of COVID-19 and other infectious diseases (Sherrard-Smith et al., 2020; Bouba et al., 2021).
Infection fatality ratio and case fatality ratio of COVID-19The infection fatality ratio (IFR) and case fatality ratio (CFR) define the risk of death per infection and per case, respectively. The difference between IFR and CFR depends on the definition of the case. If infection is defined as case, then CFR equals IFR. It is very important to determine the IFR because it influences the control policy and individual risk perception. It would be straightforward to determine the IFR in a closed, small population, such as the Diamond Princess Cruise, where the CFR was 1.3% without age standardization (Russell et al. 2020) and 0.5% after age standardization (Faust and Del Rio 2020).
Influenza versus COVID-19 cases among influenza-like illness patients in travelers from Wuhan to Hong Kong in January 2020The coronavirus 2019 (COVID-19) pandemic has dominated the world for well over half a year since the early outbreak in Wuhan, China. The pandemic hit Wuhan, Hubei, China hard, and the city had been in lockdown for more than 70 days. Much attention has been focused on estimating the accurate prevalence of COVID-19 cases in Wuhan in January 2020. Even though large-scale serological studies have been conducted, the initial spread of the virus in Wuhan still remains unclear. It seems clear, though, that the COVID-19 outbreak followed the seasonal influenza epidemic.
Comparing COVID-19 and the 1918–19 influenza pandemics in the United KingdomThe fast spread and high fatality rate of coronavirus disease 2019 (COVID-19) remind us of the first pandemic in the last century — the 1918–19 influenza pandemic. Indeed, the SARS-CoV-2 and the 1918 A/H1N1 influenza virus share some common properties:
Quantifying the improvement in confirmation efficiency of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during the early phase of the outbreak in Hong Kong in 2020The deadly coronavirus disease (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, formerly 2019-nCoV), has emerged in Wuhan, China, in December 2019 (WHO, 2020). COVID-19 cases were soon exported to other Chinese cities and overseas, mainly owing to the traffic surge near the Chinese Lunar New Year (Bogoch et al., 2020; Wu et al., 2020). The first imported cases in Hong Kong were confirmed and reported on January 23, 2020, see Fig. 1(a). Since then, the government of Hong Kong has implemented a series of control and prevention measures for COVID-19, including enhanced border screening and traffic restrictions (summary, in press; CHP, in press).
Preliminary estimation of the novel coronavirus disease (COVID-19) cases in Iran: A reply to SharifiThe worldwide outbreak of the novel coronavirus (SARS-Cov-2) pneumonia remains a major public health concern. We thank Sharifi et al.’s comments to our recent study (Zhuang et al., 2020). In that paper we adopted the similar method as Imai's (Imai et al., 2020), which was used to estimate the number of COVID-19 cases in the early stages of the COVID-19 outbreak in Wuhan, Hubei, China. The model provided a rough range estimation about the epidemic size and has been recognized by peers as a valid method in the early stage of an epidemic (Kucharski et al., 2020; Boldog et al., 2020; Ng et al., 2020).
Preliminary estimates of the reproduction number of the coronavirus disease (COVID-19) outbreak in Republic of Korea and Italy by 5 March 2020The novel coronavirus disease 2019 (COVID-19) outbreak has caused 6088 cases and 41 deaths in Republic of Korea, and 3144 cases and 107 death in Italy by 5 March 2020, respectively. We modelled the transmission process in the Republic of Korea and Italy with a stochastic model, and estimated the basic reproduction number R0 as 2.6 (95% CI: 2.3–2.9) or 3.2 (95% CI: 2.9–3.5) in the Republic of Korea, under the assumption that the exponential growth starting on 31 January or 5 February 2020, and 2.6 (95% CI: 2.3–2.9) or 3.3 (95% CI: 3.0–3.6) in Italy, under the assumption that the exponential growth starting on 5 February or 10 February 2020, respectively.
The relative transmissibility of asymptomatic COVID-19 infections among close contactsNishiura et al. (2020) estimated the asymptomatic ratio of COVID-19 was 41.6% (5 out of 12 confirmed cases) among 565 Japanese individuals evacuated from Wuhan, China. Mao et al. (2020) reported that 2 out of 78 confirmed cases are asymptomatic. One of the two cases showed RT-PCT positivity 15th days after first diagnosis. Mizumoto et al. (2020) estimated that the 17.9% of cases on the Diamond Princess Cruise Ship were asymptomatic case during the outbreak in February 2020. However, the transmissibility of asymptomatic case is unclear, and the positive RT-PCT results only imply the potential infectivity.
Preliminary estimation of the novel coronavirus disease (COVID-19) cases in Iran: A modelling analysis based on overseas cases and air travel dataThe coronavirus disease 2019 (COVID-19) was first reported in Wuhan, Hubei Province, China at the end of 2019, and soon spread to the rest of China and overseas (Bogoch et al., 2020). At the time of writing, 78 630 cases had been reported in China and 3664 cases had been confirmed in 46 other countries (World Health Organization, 2020). Iran has recently become an epicenter in the Middle East region and has seen the largest cumulative number of deaths outside China (Wikipedia, 2020). As of March 1, 2020, Iran had confirmed 987 COVID-19 cases, including 54 associated deaths (Wikipedia, 2020).
A conceptual model for the coronavirus disease 2019 (COVID-19) outbreak in Wuhan, China with individual reaction and governmental actionThe ongoing outbreak of coronavirus disease 2019 (COVID-19), has claimed 2663 lives, along with 77,658 confirmed cases and 2824 suspected cases in China, as of 24 February 2020 (24:00 GMT+8), according to the National Health Commission of the People's Republic of China (NHCPRC, 2020). The number of deaths associated with COVID-19 greatly exceeds the other two coronaviruses (severe acure respiratory syndrome coronavirus, SARS-CoV, and Middle East respiratory syndrome coronavirus, MERS-CoV), and the outbreak is still ongoing, which posed a huge threat to the global public health and economics (Bogoch et al., 2020; J.T.
The basic reproduction number of novel coronavirus (2019-nCoV) estimation based on exponential growth in the early outbreak in China from 2019 to 2020: A reply to DhunganaThe ongoing outbreak of the novel coronavirus (2019-nCoV) pneumonia in Wuhan, China and other regions remains a major public health concern. We thank Dhungana for comments to our study, Zhao et al. (2020), recently published in the International Journal of Infectious Diseases. The estimates on the basic reproduction number, R0, were carried out early in the outbreak as of January 22, 2020, when the surveillance data and the knowledge of the key epidemiological features of 2019-nCoV were limited.
Preliminary estimation of the basic reproduction number of novel coronavirus (2019-nCoV) in China, from 2019 to 2020: A data-driven analysis in the early phase of the outbreakThe atypical pneumonia case, caused by a novel coronavirus (2019-nCoV), was first reported and confirmed in Wuhan, China on December 31, 2019 (World Health Organization, 2020a). As of January 26 (17:00 GMT), 2020, there have been 2033 confirmed cases of 2019-nCoV infections in mainland China, including 56 deaths (National Health Commission of the People’s Republic of China, 2020). The 2019-nCoV cases were also reported in Thailand, Japan, Republic of Korea, Hong Kong, Taiwan and the US, and all of these cases were exported from Wuhan; see the World Health Organization (WHO) news release https://www.who.int/csr/don/en/ from January 14–21.