Australian shares have held on to gains by midday, buoyed by strength in mining, healthcare and technology shares, as investors looked past worries about a resurgence in coronavirus cases.

The S&P/ASX200 benchmark index was higher by 79.6 points, or 1.34 per cent, at 6020.70 points by 1200 AEST on Wednesday.

The All Ordinaries index was 83.1 points, or 1.37 per cent higher, at 6128.60.

Overnight, US markets ended higher as investors bought energy and materials stocks and looked beyond a recent surge in coronavirus cases.

The three major US indices ended between 1.0 to 2.1 per cent higher.

In the local market, energy and financial shares had given up some early gains by noon, but this was offset by a rebound in the healthcare and technology sectors.

Gold miners recorded hefty gains after prices of the precious metal firmed above the key $US1,800 level overnight. Newcrest, Evolution and Regis Resources were each trading between 1.5 and 2.0 per cent higher.

The big miners BHP, Rio Tinto and Fortescue were also trading between 2.0-3.0 per cent higher as iron ore prices continued to climb with demand returning in China.

Energy shares pared gains after an early rise.

Woodside Petroleum was down 2.0 per cent at $20.99 after flagging a $6.3 billion writedown and recording weak quarterly output amid a coronavirus-induced slump in oil prices.

Origin Energy also pared gains to be up 0.9 per cent at $5.80 after it outlined impairments of $1.2 billion.

However, Oil Search shares were up more than 4.0 per cent at $3.12.

In the financial sector, tow of the four major banks were trading slightly lower.

Among healthcare, ResMed, CSL and Ramsay Healthcare were each trading more than two per cent higher.

Technology shares were also higher led by Afterpay, which jumped 5.0 per cent to $69.64 after the buy now, pay later leader struck deals with Apple and Google that will allow more people to use its payment service online and in retail stores, particularly in the key US market.

Market sentiment, however, continued to be capped by the overhang of the spread of the COVID-19 cluster in Sydney. The outbreak, first detected at a pub in Sydney’s south-west, has been found to have infected more than 30 people so far and tracing continues.

Australia’s second-biggest city, Melbourne, reported 238 new cases and is already in a six-week lockdown following a resurgence of the virus.

The Australian dollar was higher at 70.09 US cents by 1200 AEST amid overall weakness by the US dollar against major currencies. It had closed at 69.54 US cents on Tuesday.