South Africa’s rand strengthened modestly on Tuesday, extending a rally from the previous session sparked by growing hopes of a COVID-19 vaccine, while investors looked ahead to local mining and manufacturing data.

At 0630 GMT the rand was 0.17% firmer at 18.3450 per dollar, holding at a four-session best reached on Monday in a strong day for emerging currencies after encouraging results from the trial of a vaccine for COVID-19.

“Growing optimism around a COVID-19 vaccine that is showing promising results helped to restore some positive market sentiment, while the Federal Reserve’s unwavering support for the U.S. economy was also perceived as risk-on by the market,” said Bianca Botes of Peregrine Treasury Solutions.

“The rand continues to be driven by sentiment, which is essentially a balancing act as it switches between risk-on and risk-off as the pandemic unfolds,” Botes added in a note.

U.S. biotech firm Moderna has produced protective antibodies in a small group of healthy volunteers during a safety trial launched in March.

Locally, releases of mining and manufacturing figures for February, albeit for the period before the nationwide coronavirus triggered lockdown, will be eyed for the likely extent of the economic slowdown already reflected in high frequency data.

Bonds extended their healthy rally, with the yield on the government issue due in 2030 down 9 basis points at 9.050% after falling 46.5 bps in the previous session.