Saudi shares reversed course to end sharply higher on Wednesday as further positive news on COVID-19 vaccine development cheered investors, while the Abu Dhabi market posted losses on a day when most major Gulf markets logged gains.

U.S. drugmaker Pfizer Inc said final results from the late-stage trial of its COVID-19 vaccine showed it was 95% effective, adding it had the required two months of safety data and would apply for emergency U.S. authorization within days. 

Moderna Inc too came out with encouraging news earlier in the week on the effectiveness of its vaccine against the infection, boosting hopes of a faster-than-expected global economic recovery. 

By the time Pfizer's latest update was released, most Gulf markets including Dubai and Abu Dhabi had closed trading for the day.

Oil prices, a crucial factor for the region's economies, firmed as hopes that producer group OPEC and its allies will delay a planned increase in oil output offset a bigger than expected build in U.S. crude inventories. 

Saudi Arabia's benchmark index added 0.6%, with lenders National Commercial Bank and Al-Rajhi Bank gaining 2% and 0.7 respectively.

Dubai's main share index added about 0.3%, with Dubai Islamic Bank and Dubai Investments leading gains, putting on 0.9% and 1.7% respectively.

However, the Abu Dhabi index logged losses for the first time in eight sessions, finishing 0.2% lower.

Telecom major Etisalat was the top loser in the blue-chip index, shedding 0.7%, while major lender First Abu Dhabi Bank ended the session 0.3% down.

In Qatar, the index bounced back from the previous session's losses to gain about 0.4%.

Qatar National Bank gained 0.7% while another finance stock, Qatar Insurance Co, tacked on 2.5%.

Outside the Gulf, Egypt's benchmark index lost 0.7%, dragged down mainly by Commercial International Bank, which fell 0.9%.

(Reporting by Aby Jose Koilparambil in Bengaluru; Editing by Jan Harvey) ((abyjose.koilparambil@thomsonreuters.com; +91 (0)8061822683;))