"The recent steady if not earth-shattering increases in global capacity are very welcome and reflect as much optimism rather than confidence in the recovery process through the next few months," OAG said.
"There remain far too many variables for anyone to be really confident about the shape of a recovery, but vaccine passports and other initiatives are all helping to build some momentum."
Experts have suggested that Vietnam test "vaccine passports" on certain groups of entrants before adopting an official policy for the holders.
Vietnam has recorded 904 cases in its latest Covid-19 outbreak since Jan. 28, but most of the 13 affected localities have gone through many days without any domestic transmission of the novel coronavirus.
With the pandemic more or less contained, air travel demand has returned to normal, with many cities and provinces, including Hai Phong, Hanoi, Ho Chi Minh City, and Quang Ninh, allowing tourism services to resume.