The players are said to harbour fears that the side effects of the vaccine could affect their performance at the tournament.
Roberto Martinez’s side is paired in Group B, alongside Denmark, Finland and Russia and will be playing their first game against the latter on June 12.
But according to a report by the Daily Mail, around half of the Belgium squad has rejected the Pfizer jab.
undefined
This is despite the country’s government and Football Association describing the vaccination as “very important”.
Among the players who refused to take the jab are Toby Alderweireld, Timothy Castagne, Thibaut Courtois and Thomas Vermaelen.
The side effects of the Pfizer jab are minimal but can cause tiredness, headaches, muscle pain, chills, joint pain and fever in more than one in ten people.
Meanwhile, the head of Belgium's Task Force COVID-19 Vaccination Strategy, says some of the players have since received the jab, while others prefer to take it after the tournament.
“A number of Red Devils had already been vaccinated abroad, a number of them have recently experienced Covid,” he is quoted as saying by the Daily Mail.
“The latter have antibodies and prefer to be vaccinated after the tournament. Of those who were not vaccinated, the vast majority had themselves vaccinated upon arrival in our country.”
Belgium are the number one ranked country in the world and will be aiming to win their first-ever trophy at Euro 2020.