VVMs
Does VVM change colour as soon as exposed to t° >8°C?
No, vaccine can be exposed to temp. > 8°C for limited time.
If vaccine is back in fridge, does colour reverse back?
No! VVM colour change is irreversible.
Are VVMs for OPV the same as for other antigens?
No. VVM is usually specific for each vaccine.
If VVM does not reach discard point, can vaccine be used after expiry date ?
No. Expired vaccine should NEVER been used.
I kept one vial of Hepatitis B vaccine with VVM in my pocket for 20 days and VVM was still intact (colour did not change). Why?
Because the VVM of Hepatitis B vaccine will change it color in 30 days at 37C