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Caution needed in using oral polio vaccine beyond the cold chain: vaccine vial monitors may be unreliable at high
Ashutosh Shrivastava1, Neeraj Gupta, Pramod Upadhyay
1St Stephens Hospital, Delhi, India.
Insights
Vaccine vial monitors (VVMs) may not accurately indicate spoilage in high temperatures, potentially compromising oral polio vaccine (OPV) efficacy. This study highlights the need for caution with VVMs in hot climates.
Area of Science:
- Immunology
- Vaccinology
- Public Health
Background:
- Oral polio vaccine (OPV) is crucial for preventing poliomyelitis in children under five.
- Maintaining the cold chain for OPV is vital for its potency.
- Vaccine Vial Monitors (VVMs) are assumed reliable across all temperatures, with testing at 37°C.
Purpose of the Study:
- To evaluate the reliability of VVMs when exposed to high temperatures encountered in field conditions.
- To determine if VVMs accurately reflect vaccine potency loss at elevated temperatures.
Main Methods:
- Vaccine vials equipped with VVMs were incubated at 37°C, 41°C, 45°C, and 49.5°C.
- Time-lapse photography captured VVM changes hourly to identify their discard point.
Main Results:
- VVMs functioned correctly at 37°C and 41°C.
- At 45°C, VVMs reached the discard point at 16 hours, while vaccine potency dropped by 14 hours.
- At 49.5°C, VVMs indicated discard at 9 hours, significantly later than the expected 3 hours.
Conclusions:
- VVMs cannot be solely relied upon in high-temperature environments.
- Careful consideration is required when implementing 'outside the cold chain' (OCC) protocols for vaccine storage and administration.
Background & Objectives:
Stabilized live attenuated oral polio vaccine (OPV) is used to immunize children up to the age of five years to prevent poliomyelitis. It is strongly advised that the cold-chain should be maintained until the vaccine is administered. It is assumed, that vaccine vial monitors (VVMs) are reliable at all temperatures. VVMs are tested at 37°C and it is assumed that the labels reach discard point before vaccine potency drops to >0.6 log10. This study was undertaken to see if VVMs were reliable when exposed to high temperatures as can occur in field conditions in India.
Methods:
Vaccine vials with VVMs were incubated (10 vials for each temperature) in an incubator at different temperatures at 37, 41, 45 and 49.5°C. Time-lapse photographs of the VVMs on vials were taken hourly to look for their discard-point.
Results:
At 37 and 41°C the VVMs worked well. At 45°C, vaccine potency is known to drop to the discard level within 14 h whereas the VVM discard point was reached at 16 h. At 49.5°C the VVMs reached discard point at 9 h when these should have reached it at 3 h.
Conclusion:
Absolute reliance cannot be placed on VVM in situation where environmental temperatures are high. Caution is needed when using 'outside the cold chain' (OCC) protocols.
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