Emergence of SARS-CoV-2 and the COVID-19 pandemic

On 31 December 2019 the Wuhan Municipal Health Commission in Hubei Province, China, reported a cluster of pneumonia cases of unknown cause. The cluster was linked to a seafood wholesale market. Three of the patients, a 49-year-old woman and men aged 61 and 32, had been admitted to a Wuhan hospital on 27 December, and lung-lavage samples collected at Wuhan Jinyintan Hospital on 30 December went to the Chinese Center for Disease Control and Prevention in Beijing.

Tests for the four common human coronaviruses were negative. A China CDC team, with Na Zhu as first author and Wenjie Tan, George Gao and Guizhen Wu as corresponding authors, sequenced the samples on Illumina and nanopore machines and found a betacoronavirus no one had described. They grew it in human airway epithelial cells and photographed particles 60 to 140 nanometers across, ringed with spikes like a solar corona. They called it 2019-nCoV. Its genome was 86.9 percent identical to a bat SARS-like coronavirus, and it was the seventh coronavirus known to infect people. China shared the sequence publicly on 12 January 2020. The 61-year-old, a frequent visitor to the market, died on 9 January; the other two patients went home on 16 January.

Thailand confirmed the first case outside China on 13 January. On 30 January WHO Director-General Tedros Adhanom Ghebreyesus accepted his Emergency Committee's advice and declared a Public Health Emergency of International Concern, the sixth since the International Health Regulations of 2005 came into force. WHO counted 7,818 confirmed cases that day, 82 of them in 18 countries outside China. On 11 February the International Committee on Taxonomy of Viruses named the virus SARS-CoV-2, for its kinship with the SARS virus of 2003, and WHO named the disease COVID-19. By 11 March cases outside China had risen 13-fold in two weeks. With more than 118,000 cases in 114 countries and 4,291 deaths, WHO called COVID-19 a pandemic, the first caused by a coronavirus.

Reported deaths understated the toll. In May 2022 WHO estimated about 14.9 million excess deaths (range 13.3 to 16.6 million) in 2020 and 2021, counting people killed by the disease and by overwhelmed health services; 57 percent were men, and middle-income countries accounted for 81 percent. On 5 May 2023, after the Emergency Committee's 15th meeting, Tedros ended the emergency. Almost 7 million deaths had been reported to WHO by then, and he put the true figure at 20 million or more.