Jan 6 (Reuters) - Australian shares fell sharply on Wednesday, with investors struggling to find a solid footing ahead of U.S. Senate election results while concerns that a Sydney coronavirus cluster may have spread to regional areas also whacked risk appetite.

The S&P/ASX 200 index closed 1.1% lower at 6,607.1 points, extending losses to a second straight session.

Risk appetite took a backseat as investors kept an eye on the results of the runoff elections in Georgia, with U.S. futures declining and global stock prices slipping.

If Democrat challengers win, it would be easier for U.S. President-elect Joe Biden to pass big fiscal spending, which is generally considered a positive.

"Australian markets have taken fright on the fall of the U.S. index futures and rapidly fading hopes of more U.S. fiscal stimulus," said Jeffrey Halley, senior market analyst for Asia Pacific at OANDA.

Losses on the Australian benchmark were wide-ranging, with nearly all sectors trading in the red.

Tech stocks shed most to hit their lowest in more than three weeks, with buy-now-pay-later giant Afterpay Ltd's nearly 6% decline weighing the most.

U.S. export-reliant domestic healthcare stocks traded lower ahead of the election outcome, while a weaker U.S. dollar weighed on drugmaker CSL Ltd.

Investor jitters also prevailed over recent outbreaks in the country's two largest cities, as officials issued a new alert in Melbourne after discovering a subsequently infected man attended an international cricket match.

Analysts were wary, even though Australian health authorities said they would bring forward roll-out plans of COVID-19 vaccines by two weeks to early March.

"We've seen how quickly this can explode, so there is a concern that this could become another Victoria situation," James Tao, market analyst at CommSec said.

Bucking the trend, energy firms gained as much as 3.3%, following a 5% climb in crude prices overnight on news that Saudi Arabia will make voluntary cuts to its oil output.

In New Zealand, the benchmark S&P/NZX 50 index closed 0.3% weaker, with dairy giant A2 Milk shedding the most. (Reporting by Shruti Sonal in Bengaluru; Additional reporting by Pranav A K, Editing by Sherry Jacob-Phillips)