With an expert flick of the wrist, South African nurse Bhelekazi Mdlalose collected throat swabs from young men lining up for coronavirus testing at a run-down hostel in downtown Johannesburg.

Health workers were sent to the overcrowded block of single-room flats — mainly occupied by men from rural areas doing odd jobs in the city — as part of a mass community screening and testing (CST) campaign launched by the government last month.

Mdlalose, who is employed by Doctors Without Borders (MSF), left her family and usual job in the northwestern town of Rustenberg in March to support community work in Johannesburg.

Aged 51, she trains government health workers to handle suspected coronavirus patients correctly, checking in on CST teams deployed to townships, offices and shopping malls.

“We identify those that are COVID-19 positive and those that have symptoms,” said Mdlalose.

“These are vulnerable people,” she added, pointing out that most would not even think to visit a clinic when sick. “By being here we actually target the right group.”