A medical officer suspects that a batch of pentavalent vaccine vials may have been accidentally frozen during transport. Which test is performed to detect freeze damage in such adsorbed vaccines?
- A Visual inspection for turbidity and particulate matter
- B Reading the vaccine vial monitor stage
- C Shake test comparing sedimentation rate against a control vial ✓
- D Potency assay by enzyme immunoassay at the reference laboratory
Correct answer: C. Shake test comparing sedimentation rate against a control vial
Explanation
The shake test detects irreversible damage from freezing in aluminium adsorbed vaccines such as DPT, TT, hepatitis B and pentavalent. The suspect vial and a known frozen control vial are shaken vigorously; if the test vial sediments faster than the control, with coarse granular deposit appearing within 10 to 30 minutes, it has been freeze damaged and must be discarded. The VVM measures cumulative heat exposure, not freezing.
Reference: WHO Immunization in Practice: A Practical Guide for Health Staff, 2015 update ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.