Professor Leitch spoke to BBC Radio Scotland’s Good Morning Scotland programme on Friday where he discussed the possibility of international travel this year.
He said: “I think international leisure travel in the summer will be challenging.
“I think there will be time and countries that we bring back gradually because it’s crucial both for individuals and society, but it’s also crucial for the industries that rely on that travel, the airlines, the travel industry more broadly.”
He also discussed the possibility of a Coronavirus certificate that could include vaccination details saying: “That kind of Covid certification I think will become something that the world needs and the WHO [World Health Organisation] are looking at that even as we speak.”
Edinburgh Airport retweeted these comments on their official account saying: “Prof Leitch is right when he says it's "crucial for the industries that rely on that travel, the airlines, the travel industry more broadly."
“We thought ScoGov's aviation group was set-up to talk to those industries but again we learn more in media comments than those meetings.”
An Aviation Group was set up to help the industry prepare and cope throughout the pandemic as travel has been banned with the exception for essential reasons during lockdown.
Many airlines, including Easy Jet, were forced to cut hundreds of jobs due to the pandemic and the drop in international travel.
A spokesperson for the Scottish Government said: “As we have said previously globally, as well as here in Scotland, the aviation industry faces one of the longest recovery periods from the pandemic.
"Scotland is offering the most comprehensive non-domestic rates relief for the aviation sector in the UK and was the first country in the UK to extend the 100% non-domestic rates relief for the sector for the whole of next year.
“We’re also working with airports on route recovery, to help rebuild connectivity for business and tourism once we are able to safely lift travel restrictions.”