TAIPEI - Just a little over a month ago, nobody in Taiwan was anticipating a fresh Covid-19 outbreak, much less one occurring a whole year after the pandemic had been dealt with.
But on Friday (May 21), Taiwan's Central Epidemic Command Centre (CECC) reported 312 new locally transmitted cases and three imported ones, the seventh consecutive day the island has had over 100 local cases.
"One of the main problems Taiwan is facing is having been too successful (in containing Covid-19), it's been missing out on all the struggles other countries have experienced, so it has a lot of catching up to do," said Professor Chi Chun-huei, a public health specialist at Oregon State University's College of Public Health and Human Sciences.
Daily numbers went from dozens to hundreds in less than a week, fuelled by clusters within Taiwan's flagship China Airlines, and a quarantine hotel near Taoyuan International Airport where airline crews were being quarantined. Then local cases began to crop up in northern Taiwan.
How was this happening on an island that had sealed itself off from the outside world a year ago?
Experts said lax regulations on air crews flying cargo planes, even while borders were closed to visitors, were partly to blame for the current surge.
Amid a global shortage of automotive chips, Taiwan's key microchip industry kept going, even during the pandemic. This prompted health authorities to design an expedited quarantine procedure that drastically shortened the time in isolation for pilots.
Crew members had to quarantine for only five days, compared with 14 required for regular travellers. On April 15, this was cut further to just three days. Crew members were asked to keep tabs on their own health for the remaining 11.
During the self-monitoring stage, crew member could meet up with family and friends, but were advised to stay away from public spaces. But not all pilots complied.
Dr Chi Chia-yu, an associate investigator at the National Institute of Infectious Diseases and Vaccinology, said three days was not enough to ensure someone was Covid-free.
"A screening after just three days cannot confirm if one has been infected or not because the viral load in their blood may still be quite low," he said.
Additionally, the quarantine hotel near the airport also violated regulations, mixing guests under quarantine with regular guests and causing another infection cluster.
Just when it looked like the CECC had the airline clusters under control, another wild card was thrown into the mix, when crews brought back the "most contagious" British Covid-19 variant, said Prof Chi.
Clusters bloomed in Yilan County, Taipei and New Taipei City, and continued to grow.
In confirmed cases, about 40 per cent show no symptoms, while others can take a week or even longer to develop symptoms.
"Both groups are most contagious in the first 10-12 days after getting infected. And they tend to go running around because they don't have symptoms," said Prof Chi.
Currently, less than 1 per cent of Taiwanese are vaccinated, as Taiwan's domestic vaccines are still in phase 2 clinical trials while imported vaccines are arriving slowly in small batches.
"We only have the AstraZeneca vaccine available, and with its reports of blood clots in European recipients and how well Taiwan was doing with Covid-19, citizens and medical staff alike opted to wait," said Dr Chi.
But Prof Chi said the first jabs should not have been reserved for front-line medical workers, given the low load of domestic cases.
"Airline crews are among the highest-risk groups. Had those pilots been vaccinated, we probably wouldn't have this outbreak now."
But the professor said the outbreak was an opportunity for the development of domestic vaccines. The island's initial success in curbing the spread made it impossible for local scientists to conduct phase 3 clinical trials - in which vaccines are tested in the "real world", an environment where confirmed cases are rampant. One "silver lining in this outbreak is how we will have a chance to do the phase 3 trials", said Prof Chi.