The UK has seen 113 cases of definite or probable vCJD
A brand of oral vaccine made from calf foetus serum was withdrawn last year after fears that it could be contaminated with BSE.
The Department of Health said that of five people who had developed vCJD in the Southampton area in 1994, two had been given vaccine made from UK-sourced bovine calf serum.
But a meeting of the independent Spongiform Encephalopathy Advisory Committee (Seac) later found no evidence that the vaccine carried a risk of vCJD.
Wellcome produced around 30 million doses of the vaccine between the late 1980s and October last year.
It was then withdrawn after the Department of Health learned that the manufacturers' assurances over the calf foetus serum were inaccurate.
Contaminated products
Seac also stressed that any historical theoretical risk had to be balanced against the "overwhelming benefits" of the immunisation programme.
Many scientists believe that humans can contract vCJD after eating contaminated products from cows with BSE.
Current vaccines use bovine material sourced in Australia, New Zealand, the USA or Canada.
There were 113 cases of definite or probable vCJD in the UK between 1996 when doctors distinguished it as a new form of the rare brain-wasting disease CJD and 3 December.
Common factors
At that date 10 patients were still alive.
The National CJD Surveillance Unit looks for common factors, including medical and personal history, in all vCJD cases.
The Department of Health said in a statement: "Finding common factors does not mean that a cause has been identified - but we report such findings to Seac so that any implications can be assessed."