(Updates prices)
    * Markets shrug-off Trump threat around aid bill
    * Brexit deal optimism boosts pound, weighs on dollar
    * Interactive graphic tracking global spread of coronavirus:
https://tmsnrt.rs/3mvcUoa

    By Diptendu Lahiri
    Dec 24 (Reuters) - Gold prices rose on Thursday backed by a
weaker dollar ahead of a widely expected Brexit trade deal, with
uncertainties around a new variant of the coronavirus
overshadowing vaccine optimism.
    Spot gold        was up 0.1% higher at $1,873.96 per ounce
by 1233 GMT. U.S. gold futures        were little changed at
$1,878.60.
    "A combination of a weaker dollar, negative real rates and
low yields along with uncertainties around the new strain of
coronavirus is helping gold at the moment," said UBS analyst
Giovanni Staunovo.
    Concerns about the spread of a more infectious coronavirus
variant which has led to a tightening of restrictions in Britain
lifted the safe-haven appeal of the precious metal.             
    Elsewhere, Britain and the European Union were on the verge
of striking a post-Brexit trade agreement, supporting sterling
and weighing on the dollar.                   
    "However, broadly, the outlook for gold is not bullish...
The recent vaccine optimism has smudged gold's appeal," said
Hareesh V, head of commodity research at Geojit Financial
Services, adding that neither did he expect gold to crash. 
    "Economic uncertainties still exist and the metal will keep
drawing support from ultra-low interest rates."
    Data on Wednesday showed the number of Americans filing
first-time claims for unemployment benefits remained elevated
but posted a fall last week.             
    Meanwhile, U.S. President Donald Trump's threat to not sign
a nearly $900 billion stimulus bill was largely brushed off by
market participants.
    "Investors are pretty optimistic about fiscal and monetary
supports from governments around the globe, even though a
vaccine reduces the might of the virus. The economy needs it,"
UBS' Staunovo said.
    Bullion, up around 24% this year, is set for its biggest
annual gain since 2010, with the unprecedented stimulus pumped
in by major governments to offset the economic blow of the
coronavirus crisis expected to lift inflation rates. 
    Silver        was up 0.7% at $25.71. Platinum        gained
0.3% to $1,017.62 and palladium        rose 0.4% to $2,332.55.

 (Reporting by Diptendu Lahiri in Bengaluru
Editing by Kirsten Donovan and Mark Heinrich)