The illness swept through the squad on Tuesday and almost led to the cancellation of last night's 2-0 friendly defeat against Turkey but team spokesman Oleksander Glyvinsky said the affected players were now on the road to recovery.
"They were out running this morning, so we would expect that they will all be fine for the opening game against Sweden," he told Reuters in a telephone interview on Wednesday.
Ukraine's team doctor Leonid Myronov told the Sport Express newspaper that the first symptoms occurred on Monday afternoon when the team masseur felt ill.
"He could barely finish his work with the team. At 4am [on Tuesday] Denys Garmash came to me with the same trouble.
"A bit later Taras Mykhalyk, Andriy Voronin, Artem Milevsky, Andriy Shevchenko and Anatoliy Tymoshchuk (pictured) all complained of feeling indisposed," he said.
Midfielder Garmash was included in the starting lineup against Turkey despite his illness, desperate to prove himself after being dropped from friendlies against Estonia and Austria.
"He was in the roughest condition, he was vomiting violently and we had to try to clean his stomach using all available methods of detox. He was extremely eager to play and said before the game he felt OK," added Myronov.
Ukraine, who are co-hosting the finals with Poland, suffered a second successive friendly defeat in the loss to Turkey after a 3-2 reverse against Austria last Friday.
After kicking off their campaign against the Swedes at the Olympic Stadium in Kiev, they face France and England in Group D.
