Alarms are sounding and a map on the screen flashes red as news comes through that a city in Taiwan has recorded more than 500 confirmed cases of the novel coronavirus. Community outbreaks are developing in neighboring districts and quarantine numbers are rapidly increasing. Frantic hordes rush out to the stores, sweeping shelves clean of food and supplies. Case numbers are projected to grow exponentially.

Luckily, this was just a simulation. New Taipei City, the municipality surrounding Taiwan’s capital, today hosted an hour-long tabletop exercise to simulate government responses in the event of a widespread community outbreak. Sixteen different government offices, as well as the military, took part in the exercise, with officials practicing how they would implement measures and coordinate across departments. They simulated lockdown measures like stepped-up travel restrictions and identity checks, widespread school and business closures, and policies to ensure adequate food supplies at wholesale markets to prevent shortages on store shelves.

“Even though Taiwan had two consecutive days of zero cases, we can’t take the situation lightly. We have to remain vigilant, because the finish line in the fight against the pandemic is still far off,” said Weiwei Chiang, a spokesperson for the New Taipei City mayor.

The mayor, Hou You-yi, has emphasized the need to “make the best preparations for the worst.” If and when a full lockdown has to be enforced, it’s imperative that frontline government staff need to know exactly what measures to implement immediately, he said (link in Chinese). Today’s simulation exercise was one way to ensure that.

New Taipei City Government The simulation exercise in action.

Taiwan has so far managed to successfully control the Covid-19 pandemic, despite its proximity to China. Last week, it recorded three separate days of zero new cases, and has been lauded for its comprehensive and timely epidemic response, which has consisted of travel restrictions and screenings, excellent public communication, strict quarantine and contact tracing measures, and the use of surveillance technology like geo-fencing to monitor quarantinees.

But Taiwan is by no means out of the woods yet. Despite its low case growth last week, 21 navy sailors were reported yesterday to have tested positive following a visit to the small Pacific island state of Palau last month. The sailors reportedly travelled to dozens of locations (link in Chinese) across 10 counties in Taiwan before testing positive, prompting fears of community transmission. The government sent text messages to 200,000 people who had been to those locations, reminding them to monitor their health conditions closely, according to Taiwan’s Central News Agency.

As countries around the world begin to ease lockdown restrictions, a major challenge will be fine-tuning how and when to roll back control measures. The delicate task of calibrating the lifting will mean keeping a close eye on the real-time effective reproductive number, or Rt, ensuring that it remains below the critical threshold of one. An Rt above one means that one infected person goes on to infect more than one other person, leading to a potentially exponential growth of the disease.

Taiwan’s simulation exercise tackled this challenge, too. In the live-streamed simulation (link in Chinese), three weeks of restrictive measures have succeeded in controlling the outbreak, with multiple consecutive days of no new cases reported by the beginning of May. Officials discuss how to slowly re-open schools while stepping up disinfecting work. Public transit is also re-opened, after a thorough disinfection of facilities, as are shops. Triumphant, hopeful music plays to close out the exercise.

“Even though the epidemic situation has improved, the epidemic has not ended… we cannot slack off, lest the epidemic spreads again,” said Liou Her-ran, deputy secretary-general of the New Taipei City government, as he concluded the exercise.

Keiji Fukuda, director of the school of public health at the University of Hong Kong, said Taiwan’s simulation exercise was “an excellent idea” that would help smooth out the often haphazard process of implementing lockdowns. “My guess is that most lockdown operations have been somewhat confused and chaotic, at least at the start, and this is a sensible way to do it better.”

Still, simulations can only do so much. The US department of health and human services, for example, last year ran a simulation of an influenza pandemic that revealed how underprepared and uncoordinated the government response was. The UK similarly ran a flu pandemic simulation in 2016, in an exercise that highlighted a shortage of intensive care beds and protective equipment. The very scenarios that played out in those simulations continue to play out in real life now.