SARs-CoV-2 | Two Tokyo returnees tested positive for antibodies

Two local residents who returned to Macau on a flight from Tokyo have tested positive for SARs-CoV-2 antibodies, according to a statement released yesterday by the Novel Coronavirus Response and Coordination Center.
The serology test results came out on Wednesday (February 3). The two individuals, who are men aged 30 and 43 years old, respectively, were on the same Tokyo flight, which landed at Macau International Airport on January 21.
In the case of the 30-year-old man, since his return, the center has carried out three viral tests, with all three tests returning negative results. On Wednesday, the center carried out an antibody check, which tested positive for antibody IgG and negative for antibody IgM.
The 43-year-old man, meanwhile, tested positive for IgM but negative for IgG. He also received three viral tests, with all results negative.
The center is not categorizing these two cases as confirmed Covid-19 infections.
A 20-year-old woman also tested positive for antibody IgM but, when re-tested, results came back negative for the same antibody. The center will arrange a second antibody test and another viral test for this woman.
Antibodies are proteins that develop when the immune system responds to a pathogen, such as a virus.
IgM is the first antibody that develops after someone has an acute viral infection. This is followed by the development of IgG antibodies. Once IgG antibodies have been developed, if a person comes into contact with the same virus again, the IgG antibodies help the immune system respond faster and more effectively than it did the first time, and may also prevent illness.
With the emergence of new variants of coronavirus with high transmissibility, and the epidemic situation in the regions in which the returnees resided before returning to the city, the risk of infection is high.
Therefore, the center is carrying out two Covid-19 antibody blood tests for the 109 returnees, in addition to the four nucleic acid tests that are being conducted within the quarantine period.
The first blood test was carried out by the Health Bureau (SSM) personnel in the medical observation hotel at 3 p.m. on Wednesday, while the next one will be on February 10 at 9:30 a.m. Failure to complete the blood tests on time will result in a delay in the completion date of medical observations.
In a note to the returnees, authorities remind them to prepare a chair from the hotel room and place it in the doorway for the SSM personnel to conduct the blood test.