A director of public heath said care home residents may not get the newly-approved Pfizer coronavirus vaccine.
Care home residents and staff are top of the government's provisional priority list for any vaccine.
But Northamptonshire's health chief, Lucy Wightman, said the Pfizer vaccine's storage and transportation requirements made that a "challenge".
She said care home residents may have to wait for the Oxford University/AstraZeneca vaccine.
The UK became the first country in the world to approve the Pfizer/BioNTech coronavirus vaccine for widespread use and the Medicines and Healthcare products Regulatory Agency (MHRA) said it was safe for roll-out next week.
The vaccine is made in Belgium, must be stored at around -70C (-94F) and, once delivered, can be kept for up to five days in a fridge.
However, speaking during a BBC East live stream on Tuesday, Ms Wightman said: "It can only be transported four times and once it's been delivered to a local area that is its fourth transportation, so it then can't be sent out to anywhere else."
She said this meant its delivery would have to be straight to mass vaccination centres or hospitals.
"But obviously what the government wanted to do was vaccinate care home residents first, and the challenge is you can't do that as you can't break up that delivery to a county," she said.
Ms Wightman said she would wait for the Oxford University/AstraZeneca vaccine for care home residents.
That vaccine, which is yet to be approved, can be kept at regular fridge temperature making distribution easier.
Prof Wei Shen Lim, chairman of the government's Joint Committee on Vaccination and Immunisation, said whether vaccines could be delivered to care homes was "dependent on deployment and implementation."
Prof Lim said there would be "flexibility" in roll-out of the Pfizer/BioNTech coronavirus vaccine and more than one type of vaccine would be needed to reach all vulnerable groups.
Health Secretary Matt Hancock said the first load of the Pfizer vaccine would be delivered next week and then "several millions" throughout December.