South Korean media are reporting a group of players have been forced to watch high-intensity training periods at South Korea's pre-World Cup training camp in Miami after catching colds in Florida.
Hong's side have just one more pre-tournament friendly before they start their World Cup campaign against Russia, and he hinted the virus that initially struck down Swansea midfielder Ki Sung-yueng and Busan I'Park goalkeeper Lee Bum-young has affected his training plans.
"If we're white at the beginning of training camp and red at the World Cup, then right now, we are pink," Hong said at his press conference on Thursday.
While it has not been confirmed what caused the virus, Ki and Lee reportedly first got sick when they arrived in Miami.
With a number of World Cup squads training in the south of the United States to prepare for Brazil, the transition from high humidity and heat during training to cool, air-conditioned hotel rooms, seems to be having an effect on players.
Japan's Shinji Okazaki could miss his country's final pre-World Cup friendly against Zambia on Friday with an illness caused by the regular variations in heat and humidity.
South Korea will take on Ghana on Monday in a friendly in Miami before facing Russia in Group H in Cuiaba on June 17.
Hong's men will then clash with Algeria on June 22 in Porto Alegre, before a match against Belgium in Sao Paulo four days later.
