Evaluation of precipitation time of the aluminum salts adsorbed potentially frozen vaccines used in the Polish National Immunization Schedule for their pre-qualification before the administration.

Purpose: Vaccines adsorbed on aluminum adjuvants irreversibly lose potency after freezing and their safety is affected. To prevent the administration of such vaccines, the World Health Organization developed the Shake Test designed to determine whether adsorbed vaccines have been frozen or not. However, the Shake Test is difficult and time-consuming when routinely conducted at the place of vaccination. In this study, a modified shake test for prequalification of potentially frozen vaccines was elaborated.

Materials and methods: Vaccines used in the Polish Immunization Schedule were investigated and the analysis includes an assessment of precipitation time and the influence of the container type, amount and type of aluminum compound, and a volume of vaccine dose on the precipitation time.

Results: Significant differences between the precipitation time of frozen and non-frozen vaccines routinely used in the Polish Immunization Schedule were observed. The precipitation time of all non-frozen vaccines was above 30 minutes. The longest precipitation time of frozen vaccines was 10 minutes.

Conclusion: The finding of the study can be used in practice by the personnel administering vaccines to patients. Step-by-step recommendations for the preparation of the test have been proposed in the article.