UPDATE 2-Rouble hits one-week low vs dollar on COVID-19 fears, oil price

(Adds Rosneft shares, updates prices)

MOSCOW, Nov 13 (Reuters) - The Russian rouble slipped to a one-week low against the dollar on Friday as the global rise in coronavirus cases weighed on risk assets, oil prices fell and the positive impact of hopes for a COVID-19 vaccine wore off.

The rouble has had a volatile few weeks, plunging to its lowest versus the euro since late 2014 on the eve of the U.S. election and then posting its biggest one-day gain against the dollar in four years the day after the vote.

By 1402 GMT, the rouble was 0.3% weaker at 77.57 versus the dollar, after briefly touching 77.7075, its weakest since Nov. 6.

Versus the euro, the rouble fell by 0.5% to 91.67 , far from levels of around 70 seen in early 2020 before oil prices crashed and the COVID-19 pandemic spread.

Brent crude oil, a global benchmark for Russia’s main export, was down 0.7% at $43.24 a barrel.

The rouble started falling again, coinciding with a decline in oil prices and the weakening of emerging markets currencies, Sberbank CIB analysts wrote.

The rouble showed little reaction to Russia’s decision to tap the global market for the first time in 2020, raising 2 billion euros ($2.4 billion) in Eurobonds.

Russia reported a record 21,983 new coronavirus infections on Friday as Moscow prepared to close restaurants and bars overnight in an effort to contain the pandemic.

Pfizer’s announcement this week of positive trial results from a COVID-19 vaccine it has developed with Germany’s BioNTech had a brief positive impact on markets, but they generally dismissed news about the effectiveness of Russia’s vaccine.

On the stock market, the dollar-denominated RTS index was down 1% to 1,226.7 points. The rouble-based MOEX Russian index was 0.2% lower at 3,019.3 points.

Shares in oil giant Rosneft pared losses to climb after the company said it planned to extend a share buyback programme.

Shares in business conglomerate Sistema rose around 1.7%, outperforming the market on reports its online retailer Ozon planned to raise about $750 million in a U.S. initial public offering.

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$1 = 0.8468 euros Reporting by Anna Rzhevkina; additional reporting by Alexander Marrow; Editing by Barbara Lewis and Steve Orlofsky