Reuters - Asia share prices fell Wednesday after COVID-19 vaccine trials were halted and an impasse in U.S. fiscal-aid talks hurt risk appetite. The dollar held on to gains on demand for safer assets.

Johnson & Johnson on Tuesday said it was pausing a COVID-19 vaccine trial owing to a study participant's unexplained illness. Eli Lilly and Co. later said it, too, had paused the clinical trial of its COVID-19 antibody treatment because of safety concerns. J&J shares lost 2.3% while Eli Lilly shares closed down nearly 3%.

"That just spoke to the fact that a vaccine could take longer to be delivered than what the market's expectations are calibrated toward," said CommSec market analyst Tom Piotrowski in Sydney.

MSCI's broadest index of Asia-Pacific shares outside of Japan fell 0.2%. Japan's Nikkei dipped 0.2% while Australia's benchmark index was off a touch and South Korea stumbled 0.7%.

China share indexes opened down with the blue chip CSI300 off 0.3%.

Overnight on Wall Street, the Dow Jones Industrial Average fell 0.5%, the S&P 500 lost 0.63% and the Nasdaq composite eased 0.1%.

Hopes for the passage of a new coronavirus relief package faded as U.S. House Speaker Nancy Pelosi rejected a $1.8 trillion relief proposal from the White House. This weighed on sentiment.

"U.S. stimulus talks are still going nowhere, dimming the prospect of a new round of support this side of the election," said Sydney-based NAB strategist Rodrigo Catril.

"So, for now it is hard to see a deal being agreed before Nov. 3, the market is still traveling with the notion that a new round of stimulus is coming, but at this stage this looks more likely after the election."

E-mini futures for the S&P 500 were up slightly in early Asian trading.

In currencies, the U.S. dollar boasted its best daily performance in three weeks Tuesday with its index against a basket of six comparative currencies rising 0.5%. The index was last even at 93.533. The euro was barely changed at $1.1742.

The Australian dollar has been slugged by news that China has stopped taking shipments of Australian coal, dragging the Aussie to one-week lows. It was last treading water at $0.7163. The yen gained versus the greenback to 105.32 per dollar, while sterling was last trading at $1.2932.

Bank of England Gov. Andrew Bailey on Tuesday said he didn't think the economy was undergoing a V-shaped recovery, because of headwind from a second wave of COVID-19 and underlying public caution about spending and socializing after the pandemic.

Market participants are also watching tension between the European Union and Britain after the EU demanded "substantive" movement Tuesday on fisheries, dispute settlement and guarantees of fair competition in their talks on a post-Brexit trade deal.

EU leaders will hold a summit in Brussels on Thursday and Friday to assess progress.

In commodities, the spot gold price was off 0.2% $1,887.33 an ounce. Oil slipped too, with Brent and U.S. crude off 8 cents each at $42.37 and $40.1 a barrel, respectively.