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NEW YORK, Dec 8 (Reuters) - Wall Street closed slightly higher on Wednesday, as investors cheered encouraging news about COVID-19 vaccines from Pfizer and BioNTech.

Pfizer and BioNTech said their three-shot course of the vaccine was able to neutralize the new Omicron variant in a laboratory test and they could deliver an upgraded vaccine in March 2022 if needed.

All three indexes closed higher. The S&P 1500 Airlines index touched its highest point since Nov. 24, which was just before news of the variant emerged.

Investors had been worried Omicron could force new restrictions in countries and hurt the global recovery. In a bid to slow its spread, Britain said it could implement tougher measures, including advice to work from home, as early as Thursday.

While Pfizer said Omicron protection was reduced among people who took just two doses of the vaccine, investors were still somewhat reassured.

With Nasdaq outperforming the Dow Paul Nolte, portfolio manager at Kingsview Investment Management in Chicago described the session as a "perfect risk-on kind of day."

"A lot is revolving around virus news. It's a reopening trade more than anything else," said Nolte.

Investors were also keeping their eye on interest rates.

"Equity investors are buying into thesis that rates won't have to go up very much to tame inflation. It makes them more comfortable buying stocks although more inclined to buy quality growth stocks than cyclicals," said Jack Ablin, chief investment officer at Cresset Capital Management in Chicago.

According to preliminary data, the S&P 500 gained 14.56 points, or 0.31%, to end at 4,701.31 points, while the Nasdaq Composite gained 99.33 points, or 0.63%, to 15,786.25. The Dow Jones Industrial Average rose 33.74 points, or 0.09%, to 35,753.17.

WHO director-general Tedros Adhanom Ghebreyesus said governments should urgently reassess their national responses to COVID-19 and accelerate their vaccination programs.

So-called reopening stocks, most affected by the pandemic's lockdowns, were among the S&P's top gainers on Wednesday. These included Norwegian Cruise Line, Carnival Corp and Royal Carribean.

Goodyear Tire & Rubber Co rose after Deutsche Bank upgraded the stock to "buy" from "hold".

Stanley Black & Decker advanced after Sweden's Securitas agreed to buy its electronic security solutions business for $3.2 billion. (Additional reporting by Devik Jain and Shreyashi Sanyal in Bengaluru; Editing by Maju Samuel)