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Efforts to contain coronavirus have, for the most part, failed – COVID-19 is now a global pandemic, and the strategy of many badly affected countries is now one of damage control: to delay the spread of the virus so that health systems will not be overwhelmed.
The stability of the virus may help explain how it was able to spread so quickly, and why it is so difficult to contain. A preprint study detected viable viruses in aerosols up to 3 hours after aerosolisation. On harder surfaces, the virus persisted for longer: 24 hours on cardboard and 2-3 days on plastic and stainless steel.
Another major factor could be the infectiousness of asymptomatic carriers. According to an analysis of infections in Singapore and Tianjin, the majority of transmissions were probably from people who were symptom-free at the time. This confirms one of researchers’ main concerns at the start of the outbreak, and means that isolating confirmed cases may not be as effective as was originally hoped.
With widespread infection now inevitable in many countries, the primary aim of governments is shifting towards ‘flattening the curve’ – slowing down the rate of infection so that health systems won’t have to deal with a huge spike in cases over a short period. However, there are also risks to bringing the number of cases down too quickly. If a sufficiently large proportion of the population remain unexposed, there will be enough people lacking immune memory that a second wave of infections could spread later in the year.