HONG KONG, Feb 24 (Reuters) - Hong Kong's home prices snapped three months of decline in January, official data showed on Wednesday, starting 2021 with a modest gain amid a jump in launches and optimism that new vaccines will speed up the economic recovery.

Private home prices in one of world's most expensive markets climbed 0.13% last month, according to the data, compared with a revised 0.3% drop in December.

Prices still rose 0.08% in the full year of 2020 amid the coronavirus pandemic, barely extending a run of increases dating back to 2009 when prices were only a third of the current level.

Home transactions accelerated in February, as the financial centre stabilises from a new wave of coronavirus infections that started in November.

According to realtor data, developers have launched over 2,000 new flats so far this year, over 60% more than a year ago.

Property developers have also cast their vote of confidence in the property market by participating more actively in land auctions and offering higher bids this year.

A consortium led by Wharf Holdings won a premium land parcel at the Peak for a record floor price of $7,000 per square foot earlier this month, while CK Asset won a mass residential site in Kowloon for $1.33 billion last week.

Realtors generally expect home prices to stay sluggish in 2021 until vaccines are made widely available in the second half, with the full year seeing up to a 5% gain.

One million doses of the Sinovac vaccine arrived from Beijing in the former British colony last week, while Pfizer/BioNTech vaccine is set to arrive in the city before the end of February. Hong Kong's 7.5 million residents can get vaccinated from Feb 26.

($1 = 7.7532 Hong Kong dollars) (Reporting by Clare Jim; Editing by Sam Holmes)