Pfizer ( PFE ) launched a pilot delivery program for its experimental Covid-19 vaccine in four U.S. states, as the drug maker seeks to address distribution challenges stemming from its ultra-cold storage requirements, Reuters notes. Rhode Island, Texas, New Mexico, and Tennessee were picked due to their differences in overall size, diversity of populations, immunization infrastructure, and urban and rural settings. The four states will not receive vaccine doses earlier than other states by virtue of the pilot, nor will they receive any differential consideration.