MADRID, Jan 18 (Reuters) - The world tourism industry barely improved last year compared to 2020, with all indicators staying way below pre-pandemic levels and industry professionals not expecting a full recovery before 2024, the World Tourism Organization (UNWTO) said on Tuesday. The tourism industry suffered a huge blow in 2020 as a result of lockdowns and travel restrictions aimed at curbing the spread of COVID-19, which made people around the world limit their activity and lose their livelihoods. Rising vaccination rates and the easing of travel restrictions did allow a small rebound in the second half of 2021, Madrid-based UNWTO said in a report, though the spread of the Omicron variant in December triggered another dip in both travel bookings and industry optimism. "The pace of recovery remains slow and uneven across world regions due to varying degrees of mobility restrictions, vaccination rates and traveller confidence," the report said. Southern Mediterranean Europe, Central America and the Caribbean saw the biggest increases in tourist arrivals compared with 2020, but were still respectively 54%, 56% and 37% below the 2019 numbers. Meanwhile the number of tourists in the Middle East and the Asia Pacific kept falling in 2021, tumbling to 79% and 94% below pre-pandemic levels respectively as many destinations remained closed to non-essential travel. Global tourism"s direct gross product rose 19% in 2021 from 2020 to $1.9 trillion, the report said, as each tourist spent more and stayed longer than in 2020. But the tourism industry"s revenue still barely surpassed half its 2019 levels. Around 64% of tourism professionals polled by the UNWTO in December do not expect a full recovery before 2024 or later - up from the 45% polled in September, when perspectives for travel revival had not yet been marred by Omicron. "The recent rise in COVID-19 cases and the Omicron variant are set to disrupt the recovery and affect confidence through early 2022 as some countries reintroduce travel bans and restrictions for certain markets," the report said.