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* GlaxoSmithKline slumps on COVID-19 vaccine development

* Vodafone gains after earnings beat estimates

* Glencore rises after maintaining 2021 output targets

* FTSE 100 down 0.1%, FTSE 250 adds 0.3%

Feb 3 (Reuters) - The FTSE 100 slipped on Wednesday, as falls in healthcare stocks offset gains elsewhere driven by investors' hopes that mass vaccinations would accelerate an economic revival, while Vodafone jumped after its earnings beat estimates.

GlaxoSmithKline Plc lost 6.3% and was the biggest drag on the index, after warning of a bigger than expected fall in 2021 earnings as the COVID-19 pandemic continues to disrupt other areas of healthcare.

"GSK's expected new dividend policy will mean lower payouts, and thus the stock, a noted income stream for investors, has taken a knock, with fears that AstraZeneca might have to follow suit, leading to a small decline for that company’s shares too," said Chris Beauchamp, chief market analyst at IG.

The blue-chip FTSE 100 index slid 0.1%, with AstraZeneca Plc, Smith & Nephew plc and Hikma Pharmaceuticals also weighing on the index, while the mid-cap index added 0.3%.

The export-oriented and commodity stocks-heavy FTSE 100 has rebounded from early-2021 losses to trade 1.3% higher for the year, as vaccinations pick up pace, corporate earnings improve and commodity prices increase.

A survey indicated that Britain's third national coronavirus lockdown has put the economy on course for a sharp contraction in early 2021, but services companies - buoyed by progress on vaccinations - are confident about recovery.

Britain's health minister on Wednesday defended his decision to give a shot developed by Oxford University and AstraZeneca to all age groups including over-65s, saying this was supported by scientific evidence.

Vodafone, the world's second-largest mobile operator, rose 5.9% and was the top boost to the FTSE 100 after saying its organic service revenue returned to growth in its third quarter, beating analysts' expectations.

Glencore, which mines coal, nickel, silver, zinc and copper, added 0.9% after affirming all of its production targets for 2021. (Reporting by Shashank Nayar and Shivani Kumaresan in Bengaluru; editing by Uttaresh.V and Kevin Liffey)