Singapore has largely been spared from astronomical Covid-19 case counts and lengthy lockdowns due to an early response and an elaborate surveillance system. Before the virus even had a name in late January 2020, Singapore had implemented travel restrictions and an efficient test, trace, and isolate system with penalties in place for those who disobeyed. Yet, Singapore is now experiencing a new surge of cases, despite having vaccinated a quarter (25.3%) of the population. Similar outbreaks in Vietnam and Taiwan who have previously controlled the virus well should serve as a warning to countries that are rolling back restrictions and opening up.  

As of 24 May 2021, the Singapore Ministry of Health has confirmed 24 new cases of locally transmitted COVID-19 infections. Of these cases, 22 are linked to previous cases, amongst which 12 have already been placed on quarantine, and 10 were detected through surveillance. The remaining 2 cases are presently unlinked to previous cases. In total 36 new cases were reported as of May 24, 2021. 

Singapore has been able to effectively trace and link the majority of new cases to 24 active clusters, involving locations such as Changi Airport, Tock Seng Hospital, Changi Prison Complex, and a tutoring center called Learning Point. There are 78 vaccinated individuals who have been infected with Covid-19 and are mostly frontline workers, compared with about 300 unvaccinated cases, according to Health Minister Ong Ye Kung. Vaccinated cases were either asymptomatic or mildly symptomatic, yet it emphasizes how we must factor breakthrough cases into our public health strategies. 

Teo Yik Ying, Dean of the National University of Singapore’s Saw Swee Hock School of Public Health, told The Washington Post the outbreak was a “stark reminder” that people who have been vaccinated can still be infected, although they are unlikely to progress to a severe disease stage where they need to go to a hospital.

The Changi Airport cluster is now linked to 100 cases and the largest of 24 active clusters in Singapore. This cluster is named after a fully vaccinated 88-year-old Singaporean man who works as a cleaner at the airport who tested positive for Covid-19 on May 5. At least 22 cases in the cluster have tested preliminarily positive for the B.1.617 India variant.  

The third-largest cluster is the Learning Point Center, which is linked to 28 cases as of Thursday May 20, 2021. 15 cases are children and 13 are adults, driving concern about the level of transmissibility of the new variants between unvaccinated children. Classmates of infected children were originally given stay-at-home orders but later shifted to hotel quarantine. Health Minister Ong Ye Kung, citing a conversation he had with the ministry’s director of medical services Kenneth Mak, said that the B.1.617 strain “appears to affect children more”.

While these case numbers may seem insignificant compared to global case counts, these cases are leaking from a tightly controlled Covid-19 response where cases are closely traced and contacts are tested and efficiently quarantined. Countries that do not have an effective testing contact tracing and quarantine system in place or who relaxes their systems would suffer from a far greater outbreak. Plunging case counts in the U.S. and the U.K. have some wrongfully assuming that the impact of the variants was overstated, but we must not get complacent. Vaccine rates in the U.S. are beginning to plateau and breakthrough cases are occurring. Quarantine rules for international travelers entering the U.S. are largely based on the honor system. As cities reopen and bars, restaurants and offices start to fill up with unmasked individuals we will find ourselves vulnerable to similar outbreaks