• health policy
• epidemiology
• infection control

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of the coronavirus disease 2019 (COVID-19) pandemic, is the worst challenge for a century for international health and financial systems. It was declared a global pandemic on 11 March 2020, 6 weeks after it had first been reported from China as a new respiratory virus.1 By then, 118 000 cases had been reported from 114 countries and 4291 people reported to have lost their lives.1 Only 7 weeks later, as of 5 May, 3 544 222 cases of COVID-19, including 250 977 deaths, have been reported from 187 countries and regions, and maritime quarantine.2

While severity and mortality have been highest in people with underlying morbidities,3 no age group is immune from COVID-19 nor are the rich and famous. Reasons are unclear for more severe disease in males and, at least in the UK and USA, in ethnic minority groups. Members of many governments have been affected, including the British Prime Minister Boris Johnson, now discharged from hospital after a spell in intensive care. Reported mortality varies widely between countries with apparently similar economic development.4 Influences on reported case fatality ratios—the number of deaths divided by the number of reported cases—include the number tested, who is tested, test accuracy, demographics for age and comorbidity, and capacity and standards of healthcare staff and facilities. More reliable data, reported mortality, on 5 May ranged in the worst affected countries in Europe, for example, from 80 in Germany to 423 in the UK, 481 in Italy and 684 in Belgium per million in the general population2 and in North America 102 per million in Canada but 204 per million in the USA.2 These figures may reflect considerable underestimates of actual mortality, as deaths from COVID-19 among care home …