Pfizer Inc has said it was starting a pilot program for Covid-19 immunisation in four US states to help refine the plan for the delivery and deployment of its vaccine candidate.

The US drugmaker said it had selected Rhode Island, Texas, New Mexico, and Tennessee for the program because of their differences in overall size, diversity of populations and immunisation infrastructure, as well as the states’ need to reach individuals in varied urban and rural settings.

“The four states included in this pilot program will not receive vaccine doses earlier than other states by virtue of this pilot, nor will they receive any differential consideration,” Pfizer said in a statement.