Origins tracing and research work of COVID-19 should be carried out based on laboratory samples collected around the world prior to its outbreak in 2019, said a Mozambican health expert.

"It is important to carry out investigations on samples stored for the last three or four years in laboratories in various parts of the world," said Eduardo Samo Gudo, deputy director of Mozambique's National Health Institute, in a recent interview with Xinhua, adding that samples extracted from animals should be included.