Paceman Jofra Archer's breach of bio-secure protocols could have been a "disaster" and ended up costing the board tens of millions of pounds, England and Wales Cricket Board (ECB) director of cricket Ashley Giles has said.
England dropped Archer from the second test against the West Indies following the breach, announcing the decision only hours before the start of the match on Thursday.
The ECB did not state the nature of the violation but media reports said the Barbados-born 25-year-old exited the bio-secure bubble to go to his flat in Brighton after the series opener in Southampton.
"This could have been a disaster. The ripple effect this could have had through the whole summer could have cost us tens of millions of pounds," Giles told British media.
"The potential knock-on effect I don't think he could have understood. He's a young man, young men make mistakes. He has to learn from them."
Archer, who has apologised, will commence five days of isolation and have two COVID-19 tests. England coach Chris Silverwood said the player would receive plenty of support.
"He knows he has done that and we will support him the best we can," Silverwood said.
"He's got five days stuck in a hotel room, so we've got to make sure he's alright from a well-being point of view, that we look after him."