Chapter 1 12 1.1 A CORONAVIRUS PANDEMIC Historical accounts demonstrate that pandemics have long affected humankind[1]. Perhaps surprisingly, it was only in 2015 that experts met at the World Health Organization (WHO) headquarters in Geneva to generate a list of priority diseases with pandemic potential, for which research and development (R&D) of vaccines and therapeutics were urgently needed. In this R&D priority list, emphasis was placed on pathogens for which no or limited diagnostic tools and treatment options existed, including two coronaviruses that had recently demonstrated their pandemic potential: severe acute respiratory syndrome coronavirus (SARS-CoV, hereafter “SARS-CoV-1”) and Middle Eastern respiratory syndrome coronavirus (MERS-CoV)[2]. Despite the steps taken in 2015, gaps in our pandemic preparedness framework remained, allowing for the emergence and subsequent global spread of SARS-CoV-2 in 2020. At the time of writing, more than half a billion cases of SARS-CoV-2 infection and almost 7 million COVID-19 deaths have been reported worldwide[3] – both expected to be gross underestimations. In the general introduction, I present the epidemiological, clinical and virological features of COVID-19 in the Netherlands and worldwide, our current understanding of ‘long COVID’, and the aims of this thesis. 1.2 COVID-19 WORLDWIDE AND IN THE NETHERLANDS Initial spread of SARS-CoV-2 globally On 31 December 2019, the WHO’s outbreak surveillance system first noticed an unofficial report that raised concern. This report described a cluster of patients who had been hospitalised with atypical pneumonia and shared an epidemiological link to the Huanan Seafood Wholesale Market in Wuhan, China[4]. Following verification of the statement, further investigation quickly identified that human-to-human transmission had taken place[5], sparking urgent questions regarding the transmissibility and virulence of the causal agent. In subsequent weeks, the full genetic sequence of SARS-CoV-2 was shared online[6], enabling the development of diagnostic polymerase chain reaction (PCR) tests. As more countries began testing symptomatic individuals travelling from areas where transmission had been confirmed, exponential global spread of the virus was revealed. The WHO declared a Public Health Emergency of International Concern (PHEIC) on 30 January 2020[7], at which stage the total confirmed case numbers had already risen to almost 10,000 and the novel coronavirus had spread to more than 18 countries[8] (Figure 1.1).
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