COVID-19: How Singapore’s ‘circuit breaker’ helps to prevent further spread

Singapore’s ‘circuit breaker’ measures aim to lower the basic reproduction number of COVID-19, also known as R0 (prounounced R-naught), and reduce the average number of people who catch the virus from a single infected person.

According to Vice Dean (Research), Associate Professor Alex Cook, data suggests that Singapore’s cumulative measures to contain the outbreak have been successful in driving down R0 to be at or below one since the start of the outbreak in January. This means that each infected person here spreads the disease to about one other person on average.

While this may seem surprising given the growing number of daily cases, many of these were likely to have been infected by people who had caught the virus overseas, where the full-blown epidemics took place, said Assoc Prof Cook.

He added that if R0 had been as high as two to three here, as it is estimated globally and in many of the worst-hit places, then Singapore would have had substantially more cases.

Overcoming this outbreak is a challenging task that requires all hands on deck. While scientists around the world race for vaccine and treatment options, individuals can play their part by following the social distancing measures that have been put in place. This will prevent the number of cases from surging to the extent that it overwhelms the healthcare system.

R0 indicates the transmissibility of the disease in the absence of control. It is not a static number and depends on a range of factors, including biological and social factors.

“It is difficult for us to control the biological factors, as it is not easy to change the dynamics of how the virus acts within a body. But we can change the social factors, such as the number of people a patient is exposed to, for example.”

— Associate Professor Alex Cook, Vice Dean (Research) and Domain Leader (Biostatistics and Modelling)

R0 can be reduced by social actions, such as implementing social distancing measures and by early isolation of cases through intensive contact tracing.

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