Human clinical trials in Brazil for a potential coronavirus vaccine developed by Oxford University started this weekend, sponsor Lemann Foundation said in a statement late on Monday.

Trials will count on 2,000 health worker volunteers in Sao Paulo and 1,000 people in Rio de Janeiro and are being conducted by Universidade Federal de Sao Paulo and hospital chain Rede D'Or, respectively.

Brazil’s health regulator Anvisa approved human clinical trials for the potential vaccine, developed by Oxford and supported by AstraZeneca Plc, earlier in June.

Brazil, where the disease is still rife, is the first country outside the United Kingdom to start testing the Oxford vaccine.

Researchers expect to launch the vaccine by year-end.