Current tests for SARS-CoV-2, the virus that causes COVID-19, look for genetic material of the virus, for instance in saliva or nasal, oral, or anal swabs, using the Polymerase chain reaction (PCR). However, these tests can’t identify people who went through an infection, recovered, and cleared the virus from their bodies.1
Serology testing, on the other hand, looks for previous infection by detecting antibodies to SARS-CoV-2. This type of testing is invaluable for surveillance and investigational purposes.
In a world-first, a research team at Duke-NUS Medical School working with the government of Singapore has established a link between two COVID-19 clusters in Singapore via serological testing.
Using two different antibody testing platforms (virus neutralisation assay and ELISA assay), the Duke-NUS team proved that a couple was infected with COVID-19 in late January 2020, as they had very high levels of the virus-specific antibodies in the their blood. That couple then passed the virus on to another couple during a Chinese New Year gathering.2
The couple pinpointed with the serological assay had no symptoms at the time of the investigations, the ministry explained.
The result helped the MOH piece together a significant piece of evidence which confirmed links between church clusters and the two Wuhan travelers.
Researchers are eagerly awaiting serological testing, not just to follow the virus’s path. “It will allow us to trace in a much more population-based way who has had the infection,” says Nigel McMillan, an infectious disease specialist at Griffith University, Gold Coast. For instance, “Many cases seem to be spread from asymptomatic patients who we can’t identify easily.” Serological tests are “essential to better understand the epidemiology of COVID-19,” says Keiji Fukuda, an epidemiologist at the University of Hong Kong.1
The test was developed by a team led by Linfa Wang, an emerging disease specialist at Duke-NUS. In blood samples from recovered patients, the team identified antibodies targeting the spike protein that proved able to block the virus from killing cells in laboratory tests. In parallel, they created synthetic viral proteins that can detect those antibodies in a blood sample without having to use the live virus.1