- The Vaccine Vial Monitor (VVM) is a time and temperature
sensitive colored label that provides an indication of the
cumulative heat to which the vial has been exposed. VVMs were
first introduced on OPV vials supplied to UNICEF and WHO in
1996. The VVM warns the end user when exposure to heat is likely
to have degraded the vaccine beyond an acceptable level. It is used
especially for temperature monitoring of OPV, which is the most
thermo labile of all vaccines. The VVM is applied to the outside of a
vaccine vial, and it applies only to that vial. It cannot be taken as a
surrogate marker for the potency of the vaccine in other vials of the
(3) same lot or in the same storage facility.
VVMs consist of a temperature sensitive material, which changes
color gradually on being exposed to heat. This change of color is
irreversible, and thus corresponds to the heat induced damage to
the vaccine inside the vial. VVM’s do not give any information on
cold injury to vaccines. There are different types of VVMs available,
to be used according to the heat stability characteristics of different
vaccines.
Interpretation of the color change of VVM is as follows:
1. Inner square is white, or lighter than outer circle: If the expiry
date has not passed, vaccine can be used - 2. Inner square matches color of outer circle or is darker than
outer circle: Vaccine should be discarded, regardless of the
expiry date.
The vaccines can be used as long as the VVM has not changed color
to the “discard” level. This is of tremendous help in outreach
programs, where vaccine has to be carried to far away places, orgiven door to door. Now VVMs are available for all vaccines and
should be demanded from all manufacturers. VVMs are thus a low
cost tool for assessing the adequacy and finding the weak links in
the cold chain. They save children from receiving impotent,
ineffective vaccines and avoid vaccine wastage
Dr. Jayaprakash
Superintendent, ICH.
Institute of Child Health.
Gov. Medical College Kottayam.
Kerala, India.