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» The prevalence of the disease in the population has been the subject of several studies. One study found 3.8 per cent of Hong Kong residents returning from Hubei in February/March 2020 were asymptomatic carriers of the virus. Another estimated that the early spread of the pandemic in Wuhan and Seattle was far more extensive than initially reported, based on a comparison between influenza cases and confirmed COVID-19 cases. » Asymptomatic cases were also found among passengers quarantined on a cruise ship, based on seroprevalence and virus shedding there, adding more evidence to the challenge of infection control. » In the environment around hospitalised patients with SARS-CoV-2, patients’ phones were found to be the most contaminated with the virus, followed by their bed rails and toilet door handles. » A new wave of infections in Hong Kong in summer 2020 was shown to be caused by two unique clusters of SARS-CoV-2 that were both closely related to imported strains. This suggested the outbreak was likely not precipitated by silent carriers from previous waves. » Superspreading events, in which a few infected patients infect many people, were identified in a study of 1,038 SARS-CoV-2 cases who were confirmed between January 23 and April 28. HKUMed researchers estimated 19 per cent of the cases seeded 80 per cent of local transmission. » Proof of in-flight transmission aboard aircraft was provided in September when an international team of researchers, including HKUMed, showed that four patients confirmed with the virus after a 15-hour flight had identical viral genomes and were not all likely to have encountered each other before the flight. 01 The SARS-CoV-2 virus was shown to infect human airways and eyes more efficiently than SARS-CoV, implying that the eyes may be an important route of SARS-CoV-2 infection. 02 Over the past 15 years, researchers in the School of Public Health have developed methods for culturing human tissues in the laboratory and applying them to study a range of respiratory viruses, such as avian flu H5N1, H5N6, H7N9, H1N1 and MERS-CoV, as well as SARS-CoV-2. 02 01 Bronchus Mock SARS-CoV-2 SARS-CoV MERS-CoV H1N1pdm Lung Conjunctiva 15