* Tech sub-index set for best day in over two weeks
* RBA governor to speak on COVID-19 later in the day
* BHP misses quarterly estimates, flags waning demand
By Arundhati Dutta
July 21 (Reuters) - Australian shares rose on Tuesday, as promising trial results from potential COVID-19 vaccines buoyed sentiment ahead of a speech by the country's central bank governor on the pandemic.
The S&P/ASX 200 index rose as much as 0.9% in early trade, rebounding from Monday's 0.6% fall.
Trial data from three potential vaccines released on Monday raised hopes that a vaccine can train the immune system to recognise and fight the novel coronavirus without serious side effects, lifting sentiment across the globe.
All eyes are now on the minutes of the Reserve Bank of Australia's last policy meeting and a speech by Governor Philip Lowe on 'COVID-19, the labour market and public-sector balance sheets' later in the day.
The coronavirus outbreak has flared up in Victoria this month, with the country's acting chief medical officer saying it could take weeks to tame despite lockdown measures.
All major sub-indexes on the benchmark opened higher, with tech stocks leading the rebound after a surge in U.S. peers.
The tech index was on track for its best day in more than two weeks with a 3.6% jump. Buy-now-pay-later firm Afterpay climbed 5% and was one of the top percentage gainers on the index.
The gold sub-index gained as much as 2.5% after bullion prices jumped overnight to their highest level since September 2011.
Top gainers on the index were Oceanagold Corp and Ramelius Resources, adding 6.8% and 5%, respectively.
The mining index hit its highest in nearly nine years and was set for a third straight session of gains, despite a 0.2% slip in BHP Group after the index heavyweight missed quarterly estimates and flagged waning demand.
In New Zealand, the benchmark S&P/NZX 50 index rose 1.14% to 11,684.7 by 1236 GMT. (Reporting by Arundhati Dutta in Bengaluru; Editing by Subhranshu Sahu)