BEIJING, Feb. 25 (Xinhua) -- The National Medical Products Administration (NMPA) has approved two antibody test kits for the rapid detection of novel coronavirus infections.

According to the NMPA official website, it has fast-tracked three test kits for novel coronavirus infections, including two antibody test kits and one nucleic acid kit.

Zhong Nanshan, a renowned Chinese respiratory specialist, told reporters at a recent remote consultation that the two antibody test kits apply the colloidal gold-based method to detect IgM, an antibody to the virus, on the seventh day of infection or the third day of onset.

It will be helpful for further diagnosis, said Zhong.

According to developers of the test kits, the colloidal gold-based test kits enable easy conjugation of gold nanoparticles to COVID-19 IgM/IgG antibodies in human serum, plasma and whole blood samples. The kits are easy to use and results can be observed with the naked eye within 15 minutes.

IgM antibodies are made when one is first infected with new pathogens and they are the body's first line of defense against infections. When the body senses an invader, the level of IgM will rise for a short time and then begin to drop. IgG antibodies will then kick in and increase for long-term protection.