Singapore charges ahead with antibody-based test for COVID-19

Researchers, biotech and pharmaceutical companies are scrambling to put an end to the coronavirus disease (COVID-19) outbreak’s continued global escalation. As of last week, the World Health Organization reported over 85,000 confirmed cases around the world. Antibody-based therapeutics and vaccines are in the works, but in the wake of a potential pandemic, a rapid and accurate means to positively diagnose infections is paramount for tracking and limiting the virus’ spread.

Scientists at Singapore’s Duke-NUS Medical School, led by emerging disease expert Linfa Wang, were challenged with charting the spread of infections from two local COVID-19 clusters. To this end, the team raced to develop an alternative to the current diagnostic standard: a polymerase chain reaction (PCR) which reveals the presence of viral genetic material in a given biological sample.

The caveat here is that PCR-based tests are only suitable in the active phase of the infection when the virus is still present in circulation, and a positive result doesn’t necessarily indicate the presence of “live” virus. On top of this, the PCR test cannot identify individuals who had previously been infected - making contact tracing an uphill battle.

Establishing COVID-19 patients in Singapore is exceptionally complicated, due to lingering population immunity from the 2003 severe acute respiratory syndrome (SARS) outbreak. With the SARS and COVID-19 coronaviruses sharing 80 percent homology, the test had to be exceptionally accurate and able to differentiate between the two.

The scientists were able to generate two separate serological tests for identifying antibodies against SARS-CoV-2, the virus responsible for COVID-19, in blood samples. The first was designed for rapid deployment, with an estimated 90 percent accuracy, while the other gold-standard protocol required specialized laboratory facilities and several days for a conclusive result.

The hope is that the test can complement currently-used techniques to map the dynamics of how COVID-19 is transmitted throughout the community. Additionally, this new method could help pinpoint individuals with “persistent infection”, or those that continue to spread the virus long after the initial symptoms have subsided. 

According to Nigel McMillan, an infectious disease specialist at Griffith University, such antibody-based diagnostics are critical to better understanding the epidemiology of COVID-19. “It will allow us to trace in a much more population-based way who has had the infection. Many cases seem to be spread from asymptomatic patients who we can’t identify easily.”

Sources: Science, The Straits Times.