Flags of the European Union fly outside the EU headquarters in Brussels, Belgium, May 21, 2021. The European Union (EU) recommended on Thursday to open its external borders to non-essential travel into the bloc if travellers have been fully vaccinated against COVID-19. (Photos: Xinhua/Zheng Huansong)

A Qatar Airways flight prepares for landing at the Brussels Airport in Zaventem, Belgium, May 21, 2021. The European Union (EU) recommended on Thursday to open its external borders to non-essential travel into the bloc if travellers have been fully vaccinated against COVID-19.

A Japan Airlines flight approaches the Brussels Airport in Zaventem, Belgium, May 21, 2021. The European Union (EU) recommended on Thursday to open its external borders to non-essential travel into the bloc if travellers have been fully vaccinated against COVID-19.

Flags of the European Union fly outside the EU headquarters in Brussels, Belgium, May 21, 2021. The European Union (EU) recommended on Thursday to open its external borders to non-essential travel into the bloc if travellers have been fully vaccinated against COVID-19.

A Qatar Airways flight prepares for landing at the Brussels Airport in Zaventem, Belgium, May 21, 2021. The European Union (EU) recommended on Thursday to open its external borders to non-essential travel into the bloc if travellers have been fully vaccinated against COVID-19.

Flags of the European Union fly outside the EU headquarters in Brussels, Belgium, May 21, 2021. The European Union (EU) recommended on Thursday to open its external borders to non-essential travel into the bloc if travellers have been fully vaccinated against COVID-19.

European Commissioner for Justice Didier Reynders makes a statement on the provisional political agreement on the EU Digital COVID-19 Certificate during a press conference in Brussels, Belgium, May 21, 2021. The European Union (EU)'s COVID-19 certificate will be up and running from July 1, Didier Reynders said Friday.