Antibody Test To Detect Coronavirus Developed In Singapore
Researchers at the Duke-NUS Medical School in Singapore tested the first experimental antibody test for Covid-19 to confirm if a patient among the two patients who formed a missing link between two clusters of cases that each occurred in a Singaporean church is infected with the novel coronavirus or not. The test needs to be validated before it can be used widely.
Scientists around the world are racing to develop antibody tests or serological tests to detect coronavirus which could confirm if a person was infected even after he is recovered from the disease.
Currently, the infection is detected through genetic analysis, they look for viral genome in saliva, or oral, nasal, or anal swabs using the polymerase chain reaction. These tests can give a positive result only when the virus is present. It cannot identify people who had infection before, recovered and cleared virus from the body.
The health officials at Singapore’s health ministry had been trying to trace the source of a cluster of 23 Covid-19 cases at the Grace Assembly of God church. The contact tracers were able to identify the primary case, a 28-year-old man who fell ill on 29 January but could not determine how he got infected.
Another cluster of Covid-19 cases originated from a small, independent evangelical congregation, Life Church and Missions which was probably seeded with visitors from Wuhan on 19 January. The primary case from Grace Assembly of God church had visited a Lunar Year celebration on 25th January with a couple who had attended the church service at Life Church and Missions seeded with Wuhan visitors. This could be the probable link between the two clusters of Covid-19 cases.
Even though the Life Church couple had developed symptoms and sought medical advice on 25th January, they were not diagnosed as Covid-19 cases due to their mild symptoms. When the contact tracers identified the Lunar New Year celebration link, they sent the couple to National Center for Infectious Diseases for tests on 18th February. Since the couple was recovered and time had elapsed, it was late to confirm if they had coronavirus infection through the PCR test. This is why the researchers used both PCR and antibody tests.
Surprisingly, the husband tested positive for the virus and the wife negative in the PCR test. The husband was isolated immediately. Both the husband and wife tested positive in the antibody tests.
Virologist Danielle Anderson of Duke-NUS said during a Tuesday briefing that this is the first time these particular tests are being used for contact tracing.
Researchers worldwide are waiting for serological testing to trace the virus’s path. It looks like many cases are spread from asymptomatic patients. Serological tests will help to understand the epidemiology of the novel coronavirus.
The antibodies identified from the blood samples of the couple were those that target the spike protein. The researchers also developed synthetic viral proteins to detect the antibodies in blood to avoid the use of a live virus.
Bart Haagmans of Erasmus Medical Center, who is working in collaboration with Utrecht University on serological tests itself said the serological tests need to be validated to confirm they are reliable and specific to Covid-19. One major challenge in developing serological tests would be the possible cross-reactivity due to the similarities between Covid-19 and SARS viruses. But the new test is highly efficient in distinguishing the two viruses.
According to the paper published online on 17th February in Emerging Microbes & Infections, a team at the Wuhan Institute of Virology in China used an in-house test to show that serologic testing can be used to confirm infections. A diagnostics manufacturer, EUROIMMUN has also claimed to have developed an antibody test for detecting coronavirus and its waiting for approval.
Singapore’s aggressive contact tracing efforts and quarantine strategies have possibly limited the spread of the disease compared to countries like Iran, Italy, and South Korea. As of now, 108 confirmed cases are reported in the city.