In an effort to create IPV at a lower cost, researchers are working on adding adjuvants to the vaccine. This same method was utilized to make a greater number of H5N1 vaccines at a low cost. Adjuvants are materials that can enhance the immune response so that a lower dose of the inactivated trivalent polio vaccine will be needed. The researchers used multiple groups of rats for testing, one group was given the full dose of IPV and the other groups were given the vaccine with the various adjuvants. The vaccine with adjuvants tested similarly to the vaccine alone on virus-neutralization titers. The next step is to figure out the most effective adjuvant, based on the results and those commonly used in practice.