UNTIL 2020, many experts thought it was impossible to halt the spread of a respiratory virus once it started to spread out of control. During the course of the year, many countries have shown it is possible to contain the coronavirus even without the help of a vaccine 鈥� but only a few have managed to keep it contained.
By late January, the crowded metropolis of Wuhan in China was reporting thousands of new covid-19 cases every day. It seemed inevitable that the outbreak would spread throughout the country of 1.4 billion people, especially as it was becoming clear that the virus can be infectious even when a person shows no symptoms.
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Instead, China took decisive action. It halted all movement into and out of the city, closed public transport and most shops and quarantined those who tested positive. In February, a agile and aggressive disease containment effort in history鈥�.
It worked. 鈥淐hina did something that many people thought鈥� impossible,鈥� Aylward told New Scientist in March.
At the time, many researchers still doubted that the same could be achieved in Western countries. But by late March, with death rates soaring, many nations in Europe were forced to introduce lockdowns too, which did greatly reduce case numbers.
The harder part is preventing a resurgence. New Zealand, which has a population of around 5 million, managed to eliminate the virus for a while by quickly imposing a tough lockdown and shutting its borders, but has had a small number of cases since, after another outbreak began in August. Other places to eliminate the virus are isolated islands with small populations.
Only a few countries with large numbers of people have successfully prevented major outbreaks, including Thailand, Vietnam, Taiwan and South Korea. In fact, South Korea has done so well that its economy
Testing, tracing and isolation has been central to South Korea鈥檚 strategy as well as 鈥渧ery stringent lockdown-type measures鈥�, says Amy Dighe at Imperial College London.
China, meanwhile, has prevented another major outbreak. Its strategy has included mass testing of entire cities, including 11 million people in Wuhan.
