Asian stock markets declined Friday as questions about the effectiveness of one possible coronavirus vaccine weighed on investor optimism.

Benchmarks in Tokyo, Hong Kong, Seoul and Sydney retreated while Shanghai gained.

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A currency trader watches monitors at the foreign exchange dealing room of the KEB Hana Bank headquarters in Seoul, South Korea, Friday, Nov. 27, 2020. Asian stock markets declined Friday as questions about the effectiveness of one possible coronavirus vaccine weighed on investor optimism. (AP PhotoAhn Young-joon)

Asian stock markets declined Friday as questions about the effectiveness of one possible coronavirus vaccine weighed on investor optimism.

A currency trader passes by screens showing the Korea Composite Stock Price Index, right, and the foreign exchange rate at the foreign exchange dealing room of the KEB Hana Bank headquarters in Seoul, South Korea, Friday, Nov. 27, 2020. Asian stock markets declined Friday as questions about the effectiveness of one possible coronavirus vaccine weighed on investor optimism. (AP PhotoAhn Young-joon)

“Market participants showed increasing signs of nervousness as data errors were revealed,” said Mizuho Bank in a report.

A woman wearing a protective face mask to help curb the spread of the coronavirus stands near an electronic stock board showing Japan's Nikkei 225 index at a securities firm as a car passing by Friday, Nov. 27, 2020, in Tokyo. Asian stock markets declined Friday as questions about the effectiveness of one possible coronavirus vaccine weighed on investor optimism. (AP PhotoEugene Hoshiko)

U.S. markets were closed Thursday for a holiday.

A man wearing a protective face mask to help curb the spread of the coronavirus walks past an electronic stock board showing Japan's Nikkei 225 index at a securities firm Friday, Nov. 27, 2020, in Tokyo. Asian stock markets declined Friday as questions about the effectiveness of one possible coronavirus vaccine weighed on investor optimism. (AP PhotoEugene Hoshiko)

Investors also are dismayed that U.S. states and European governments are reimposing controls on business and travel as infection rates surge.

A man wearing a protective face mask to help curb the spread of the coronavirus walks past an electronic stock board showing Japan's Nikkei 225 index at a securities firm Friday, Nov. 27, 2020, in Tokyo. Asian stock markets declined Friday as questions about the effectiveness of one possible coronavirus vaccine weighed on investor optimism. (AP PhotoEugene Hoshiko)

Supplemental unemployment benefits that supported consumer spending, the engine of the U.S. economy, have expired. Congress is deadlocked on a possible new aid plan.

A man wearing a protective face mask to help curb the spread of the coronavirus stands near an electronic stock board showing Japan's Nikkei 225 index at a securities firm as a car passing by Friday, Nov. 27, 2020, in Tokyo. Asian stock markets declined Friday as questions about the effectiveness of one possible coronavirus vaccine weighed on investor optimism. (AP PhotoEugene Hoshiko)

A man wearing a protective face mask to help curb the spread of the coronavirus stands near an electronic stock board showing Japan's Nikkei 225 index at a securities firm as a car passing by Friday, Nov. 27, 2020, in Tokyo. Asian stock markets declined Friday as questions about the effectiveness of one possible coronavirus vaccine weighed on investor optimism. (AP PhotoEugene Hoshiko)

Investors have been encouraged by reports of progress toward a possible vaccine. But they were uneasy after researchers questioned data that showed a candidate from the University of Oxford and AstraZeneca was 70% effective.

A currency trader watches monitors at the foreign exchange dealing room of the KEB Hana Bank headquarters in Seoul, South Korea, Friday, Nov. 27, 2020. Asian stock markets declined Friday as questions about the effectiveness of one possible coronavirus vaccine weighed on investor optimism. (AP PhotoAhn Young-joon)

A currency trader watches monitors at the foreign exchange dealing room of the KEB Hana Bank headquarters in Seoul, South Korea, Friday, Nov. 27, 2020. Asian stock markets declined Friday as questions about the effectiveness of one possible coronavirus vaccine weighed on investor optimism. (AP PhotoAhn Young-joon)

“Market participants showed increasing signs of nervousness as data errors were revealed,” said Mizuho Bank in a report.

The Nikkei 225 in Tokyo lost 0.1% to 26,506.97 and Hong Kong’s Hang Seng sank 0.2% to 26,761.22. The Shanghai Composite Index added 0.4% to 3,383.06.

The Kospi in Seoul lost less than 0.1% to 2,625.84 and Sydney’s S&P-ASX 200 fell 0.7% to 6,592.50. New Zealand and Jakarta gained while Singapore retreated.

A currency trader passes by screens showing the Korea Composite Stock Price Index, right, and the foreign exchange rate at the foreign exchange dealing room of the KEB Hana Bank headquarters in Seoul, South Korea, Friday, Nov. 27, 2020. Asian stock markets declined Friday as questions about the effectiveness of one possible coronavirus vaccine weighed on investor optimism. (AP PhotoAhn Young-joon)

A currency trader passes by screens showing the Korea Composite Stock Price Index, right, and the foreign exchange rate at the foreign exchange dealing room of the KEB Hana Bank headquarters in Seoul, South Korea, Friday, Nov. 27, 2020. Asian stock markets declined Friday as questions about the effectiveness of one possible coronavirus vaccine weighed on investor optimism. (AP PhotoAhn Young-joon)

U.S. markets were closed Thursday for a holiday.

Investors are looking forward to a possible vaccine to control the coronavirus following the deepest economic slump since the 1930s, though forecasters warn the stock market rebound might be too early to be sustained.

Those hopes were dented this week when researchers questioned how Oxford and AstraZeneca calculated the effectiveness of their vaccine. That alliance is among researchers who have reported the most progress toward a possible vaccine. The AstraZeneca CEO told Bloomberg News the company might conduct another trial.

A woman wearing a protective face mask to help curb the spread of the coronavirus stands near an electronic stock board showing Japan's Nikkei 225 index at a securities firm as a car passing by Friday, Nov. 27, 2020, in Tokyo. Asian stock markets declined Friday as questions about the effectiveness of one possible coronavirus vaccine weighed on investor optimism. (AP PhotoEugene Hoshiko)

A woman wearing a protective face mask to help curb the spread of the coronavirus stands near an electronic stock board showing Japan's Nikkei 225 index at a securities firm as a car passing by Friday, Nov. 27, 2020, in Tokyo. Asian stock markets declined Friday as questions about the effectiveness of one possible coronavirus vaccine weighed on investor optimism. (AP PhotoEugene Hoshiko)

Investors also are dismayed that U.S. states and European governments are reimposing controls on business and travel as infection rates surge.

The disease has killed more than 1.4 million people worldwide and there are 61 million confirmed cases, according to data gathered by Johns Hopkins University.

Markets are uneasy about U.S. data showing consumer spending weakening and job losses rising.

A man wearing a protective face mask to help curb the spread of the coronavirus walks past an electronic stock board showing Japan's Nikkei 225 index at a securities firm Friday, Nov. 27, 2020, in Tokyo. Asian stock markets declined Friday as questions about the effectiveness of one possible coronavirus vaccine weighed on investor optimism. (AP PhotoEugene Hoshiko)

A man wearing a protective face mask to help curb the spread of the coronavirus walks past an electronic stock board showing Japan's Nikkei 225 index at a securities firm Friday, Nov. 27, 2020, in Tokyo. Asian stock markets declined Friday as questions about the effectiveness of one possible coronavirus vaccine weighed on investor optimism. (AP PhotoEugene Hoshiko)

Supplemental unemployment benefits that supported consumer spending, the engine of the U.S. economy, have expired. Congress is deadlocked on a possible new aid plan.

In energy markets, benchmark U.S. crude lost 67 cents to $45.04 per barrel in electronic trading on the New York Mercantile Exchange. Brent crude, used to price international oils, lost 11 cents to $47.90 per barrel in London.

The dollar fell to 104.07 yen from Thursday’s 104.25 yen. The euro rose to $1.1920 from $1.1906.

A man wearing a protective face mask to help curb the spread of the coronavirus walks past an electronic stock board showing Japan's Nikkei 225 index at a securities firm Friday, Nov. 27, 2020, in Tokyo. Asian stock markets declined Friday as questions about the effectiveness of one possible coronavirus vaccine weighed on investor optimism. (AP PhotoEugene Hoshiko)

A man wearing a protective face mask to help curb the spread of the coronavirus walks past an electronic stock board showing Japan's Nikkei 225 index at a securities firm Friday, Nov. 27, 2020, in Tokyo. Asian stock markets declined Friday as questions about the effectiveness of one possible coronavirus vaccine weighed on investor optimism. (AP PhotoEugene Hoshiko)

A man wearing a protective face mask to help curb the spread of the coronavirus stands near an electronic stock board showing Japan's Nikkei 225 index at a securities firm as a car passing by Friday, Nov. 27, 2020, in Tokyo. Asian stock markets declined Friday as questions about the effectiveness of one possible coronavirus vaccine weighed on investor optimism. (AP PhotoEugene Hoshiko)

A man wearing a protective face mask to help curb the spread of the coronavirus stands near an electronic stock board showing Japan's Nikkei 225 index at a securities firm as a car passing by Friday, Nov. 27, 2020, in Tokyo. Asian stock markets declined Friday as questions about the effectiveness of one possible coronavirus vaccine weighed on investor optimism. (AP PhotoEugene Hoshiko)