Patients are contacting their GPs about smallpox vaccinations only to be told the vaccine is not stored at surgeries.
Health bosses say there has been confusion about the availability of the vaccine, giving the impression people can call their local doctors to get immunised.
GP surgeries in Brighton and Hove and other parts of Sussex have been approached by dozens of concerned patients wanting to get themselves protected.
The Department of Health has not introduced a mass vaccination programme and is instead targeting key workers who will be in the front line in the event of a terrorist incident.
This involves setting up regional core groups across the UK made up of doctors, nurses, public health workers and microbiologists, who will form regional core groups across the UK.
A spokesman for Brighton and Hove City Primary Care Trust said: "There have been calls made to the surgeries as a result but there are no vaccinations taking place there.
"There are stocks available nationally so we will have access to them if it becomes necessary but there is no general access to vaccinations. This is a national policy.
"We have contacted all GPs and health centres giving them this information so they can let patients know what is happening."
The Department of Health said there was no evidence of a specific threat of a smallpox attack on the UK but it was sensible to ensure the NHS could deal effectively with any potential threat.
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