Celtic manager Ronny Deila insists Virgil van Dijk does not want to leave the Scottish Premiership leaders in January.
Celtic boss Ronny Deila says keeping his best players will take priority over acquisitions in the transfer window.
Kiernan had a temporary spell at Griffin Park in November, making seven appearances for Uwe Rosler's side before returning to the Latics.
The Republic of Ireland Under-21 international featured in both central defence and midfield and played a key role in Brentford's win over Sheffield United in late November, helping to set up the first goal.
He is available for selection for the Bees' League One game at Oldham on Saturday.