United have decided on the policy because of the risk - albeit extremely slight - posed by coronavirus.
They decided against taking the striker on their winter break training camp in Spain because of concerns he may have difficulty getting back into the UK.
Ighalo, 30, is expected to travel with the squad for Monday's game at Chelsea.
BBC Sport understands Ighalo has been training with support from the club using a personalised fitness programme to get him ready for the Chelsea Premier League game.
This has been done at the National Taekwondo Centre, close to the Etihad Stadium and where he has been staying since his arrival in England 11 days ago.
Ighalo joined United on loan for the rest of the season from Chinese Super League club Shanghai Shenhua.
The death toll in China from the virus is now more than 1,350, with almost 60,000 infections in total.
Numerous sporting events have been cancelled in China and the Far East, including the Formula 1 Chinese Grand Prix.