Going global – Travel and the 2019 novel coronavirus

Abstract

Since 2009, the World Health Organization (WHO) has made five declarations of disease outbreaks considered Public Health Emergencies of International Concern (PHEIC): the 2009H1N1 (or swine flu) pandemic, the 2014 polio declaration, the 2014 outbreak of Ebola in Western Africa, the 2015–16 Zika virus epidemic and, as of 17 July 2019, the Kivu Ebola epidemic which began in 2018 [1,2]. Now, on January 30, 2020, after two meetings (the first on January 22 and 23) and a careful assessment of the situation, the Emergency Committee (EC) declared the outbreak of novel coronavirus 2019 (2019-nCoV) in the People's Republic of China a PHEIC [1]. Convened by the WHO Director-General under the International Health Regulations (IHR) (2005), the EC considered exportations to other countries and gave evidenced-based advice to the Director-General to support the final decision. The EC provided public health advice and recommendations in the midst of this outbreak [1]. The zoonotic spillover seen during this outbreak [3] has been previously witnessed with other coronaviruses pathogenic for human beings, four of them causing mild respiratory and intestinal disease, but two previously causing major concerns. The first, is the coronavirus causing the Severe Acute Respiratory Syndrome (SARS-CoV), that emerged as a global outbreak from China between November 2002 and July 2003. That epidemic, resulted in 8098 cases, with 774 deaths (9.6%) reported in 17 countries [4]. In fact, the PHEIC designation was created following an update to the International Health Regulations (2005) after that outbreak. Only a decade later, in April 2012, in Saudi Arabia, the outbreak of the Middle East Respiratory Syndrome Coronavirus (MERS-CoV) affected 24 countries, primarily in the Middle East. The MERS-CoV resulted in over 1200 cases of the virus and over 400 deaths [5]. Both viruses, primarily infect bronchial epithelial cells and type II pneumocytes [6]. However, SARS-CoV uses angiotensin-converting enzyme 2 (ACE2) as a receptor and primarily infects also ciliated bronchial epithelial cells (Fig. 1) [6–10], whereas MERS-CoV uses dipeptidyl peptidase 4 (DPP4; also known as CD26) as a receptor and infects unciliated bronchial epithelial cells (Fig. 1) [6,11–13]. Structural analyses apparently predict that 2019-nCoV uses also the ACE2 as its host receptor (Fig. 1) [9,10,14]. Recent studies suggest that the 2019-nCoV does not use other coronavirus receptors, aminopeptidase N and DPP4/CD26 [10]. Now, once again, the world faces the emergence of a new pathogen, another coronavirus, with a more important outbreak in terms of number of cases and deaths, compared to SARS-CoV and MERS-CoV [15]. Certainly, the 2019-nCoV represents a big threat to global health, with a growing number of cases, as reported by WHO (https://www. who.int/emergencies/diseases/novel-coronavirus-2019/situationreports/), requiring coordinated efforts, research and development in counter measures, sharing scientific knowledge and information to mitigate the impact of such situation [16]. After the first cases in Wuhan, Hubei province, the growth of the outbreak was predictable nationally and internationally. Recent data analyses showed that domestic train transportation significantly correlated with the number of imported cases to other provinces in China [17]. But, with Wuhan Airport having non-stop passenger flights scheduled to 113 destinations in 22 countries, in addition to the 78 domestic flights, international imported cases began to occur especially in Asia, but also abroad [18,19]. Furthermore, Beijing Capital International Airport, the largest airport in China, has non-stop passenger flights scheduled to 233 destinations in 54 countries and 127 domestic flights, including four direct routes, just two hours away, in addition to 20 routes with 1 stop, via Jinan, Changzhi, Dongying, and other major cities in China, including the largest city of Shanghai. Travelers have played a significant role in bringing new cases to other countries, with confirmed ongoing human-to-human transmission [14,20–22], and also transmission from asymptomatic individuals, as has occurred recently in Germany [22,23].