The recovery of international airline travel continues to be "stymied by extensive government travel restrictions", according to Iata.
While both international and domestic travel demand showed "marginal" improvements in May 2021 compared to April 2021, traffic remained "well below" pre-pandemic levels.
Total demand for air travel in May 2021 was down 62.7% compared to May 2019 and there was a 65.2% decline recorded in April 2021 versus April 2019.
International passenger demand in May was 85.1% below May 2019.
Willie Walsh, Iata’s director general, said it was "disappointing" that more governments are not moving "more rapidly" to use data to drive border reopening.
"We are starting to see positive developments, with some international markets opening to vaccinated travelers," he added. "The Northern Hemisphere summer travel season is now fully arrived."
"To paraphrase an old saying, when you think that all you have is a hammer, every problem looks like a nail."
Walsh said "too many governments" have continued to act "as if the only tool in their anti-Covid-19 arsenal is a blanket border closure or an arrival quarantine".
He claimed that research from "leading medical organisations" confirms that vaccinated travelers pose "very little risk" to local populations.
"It is long past time for governments to start responding to this information with more nuanced data-driven risk-based strategies," he continued.
"These will minimize the chance of importing Covid while allowing the world to reopen to travel and all the opportunities it brings to reconnect with loved ones, to realize business opportunities, to explore the world or take a well-deserved vacation."