Mohamad Al Hamad

Dear Colleagues,

Greetings!

I am writing to raise a question regarding the recent WHO-prequalified Hexavalent vaccine (HEXASIIL) manufactured by SII. There has been growing interest in switching from Penta to Hexa due to its potential advantages, such as a reduction in the number of injections needed, potential cost savings, fewer cold chain requirements, waste reduction, and additional opportunities to administer IPV doses. However, upon reviewing the available information from WHO, UNICEF, and the product's package insert, I have noticed some critical data points are missing. Specifically, there is no indication of the Vaccine Vial Monitor (VVM) type or the reliability of the shake test in case of freezing exposure.

This information is essential as it can help us advocate more effectively for the switch. Having the Inactivated Polio Vaccine (IPV) as a combined antigen in a more stable formulation adds significant value to the Hexavalent vaccine, especially in fragile contexts. It increases resilience against cold chain failures, which is a crucial consideration in a challenging operational environment.

From the data available, it is understood that the Hexavalent vaccine is an aluminium-based adjuvant vaccine. Given this, is the applicability of the shake test in case of freezing exposure still relevant? Additionally, my understanding is that for combined, multi-antigen vaccines, the VVM corresponds to the most heat-sensitive antigen. In the case of Hexa, is it VVM 7 (as standalone IPV) or do we have a more stable vaccine with VVM Type 14?

Your insights and any additional information on these matters would be highly appreciated.

Thank you