Step by step how to conduct the shake test

Summary

This video explains the step-by-step process of performing a shake test to evaluate the effect of freezing on vaccines. It emphasizes the importance of the test for liquid vaccines containing specific antigens, like diphtheria, tetanus, and hepatitis B. The video outlines the test's effectiveness in determining whether vaccines have been damaged by freezing, with 100% sensitivity and specificity. It also highlights how to properly prepare and conduct the test using a control vial and explains the outcomes: passing or failing the test based on sedimentation rates, ensuring the safe use of vaccines.

Takeaways

• 😀 The shake test is a standard and validated method to determine if vaccines have been affected by freezing.
• 😀 Freezing can compromise the potency of vaccines, especially aluminum-based adjuvant vaccines, which should not be frozen.
• 😀 Freezing of vaccines can lead to loss of potency and reduced immunogenicity, making the vaccines ineffective.
• 😀 The shake test should only be conducted when freezing is suspected, based on temperature monitoring devices or alarms.
• 😀 If a vaccine is already frozen solid, it should be discarded and not subjected to a shake test.
• 😀 The shake test should not be conducted if the vaccine develops white lumps or sediments that cannot be dissolved after shaking.
• 😀 The mechanism behind the shake test involves observing the sedimentation rate of particles in the vaccine after it is shaken.
• 😀 A frozen vaccine tends to form heavier granules that settle faster, which is key in identifying frozen vials through the shake test.
• 😀 A control vial, which has been purposely frozen, is used to compare sedimentation rates and validate the test results.
• 😀 If the test vial sediments slower than the control vial, it is safe to use; if sedimentation is faster or similar, the vaccine is compromised and must be discarded.
• 😀 The shake test is a patient-based test; the result may vary depending on the time taken for sedimentation observation, but it will always be accurate when properly conducted.

Q & A

What is the purpose of the shake test?

The shake test is used to determine whether vaccines have been affected by freezing, which can compromise their potency. It helps evaluate whether a vaccine can still be used safely.

When should the shake test be conducted?

The shake test should be conducted when freezing is suspected. This can be identified through temperature monitoring devices or alarms, or when there is visible indication of freezing in the vaccine storage.

What should be done if a vaccine is already frozen solid?

If a vaccine is already frozen solid, the shake test should not be performed. Instead, the vaccine should be discarded following standard disposal procedures.

How does freezing affect vaccines?

Freezing causes the bond between the absorbent and the antigen in the vaccine to break, leading to the formation of granules that settle at the bottom of the vial. This damages the vaccine's potency and immunogenicity.

What are the effects of freezing on aluminum-based adjuvant vaccines?

Freezing aluminum-based adjuvant vaccines, such as those containing diphtheria, pertussis, tetanus, hepatitis B, and hemophilus influenzae type b, can result in the loss of potency and compromised protective immunogenicity.

What role does phase contrast microscopy play in the shake test?

Phase contrast microscopy is used to visually confirm the presence of granules in the vaccine vial that has been frozen. It helps in identifying the structural differences between a frozen and non-frozen vaccine.

What is the procedure for preparing a frozen control vial?

To prepare a frozen control vial, take a vaccine of the same type, batch number, and manufacturer as the test vaccine. Place it in the freezer overnight until it is completely frozen, then thaw it without applying heat.

How long should the vials be shaken during the test?

The vials should be shaken vigorously for 10 to 15 seconds to ensure the contents are thoroughly mixed before observing the sedimentation rates.

What happens if the sedimentation rates of the test vial and the frozen control vial are similar?

If the sedimentation rates are similar or if the test vial sediments faster than the control vial, it means the vaccine has been affected by freezing and should be discarded.

Why is patience important when conducting the shake test?

Patience is important because the sedimentation process can take time. Health workers must wait and carefully observe the sedimentation rates to ensure accurate results. The decision time for determining pass or fail may vary among workers.