Claims of a causal link between two cases of vCJD and a batch of polio vaccine distributed in the UK in 1994 are highly unlikely to be true, say UK scientists. They also stress that there should be no risk at all of contracting vCJD from current batches of polio vaccine.
The UK CJD Surveillance Unit in Edinburgh examined the cases of five people living in the Southampton area who developed vCJD, the human form of BSE. They found that two had been given oral polio vaccine from the same batch when they were teenagers. At the time, oral polio vaccine was produced using material from British calf foetuses.
vCJD can be caused by eating material from cattle infected with BSE. And there is a theoretical risk that the vaccine could have been contaminated with BSE. However, Liam Donaldson, the government’s chief medical officer, has estimated it is “very unlikely” that infection would be transmitted through the oral polio vaccine. The government’s Spongiform Encephalopathy Advisory Committee (SEAC), which has reviewed the data on the five Southampton cases, agrees.
“All geographically associated cases are routinely investigated,” said the Department of Health in a statement. “No other vCJD cases received this batch of vaccine. This vaccine was identical to the other batches manufactured at the same time, making up 5.3 million doses.”
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Vaccine ban
Since the two victims lived in the same area and were vaccinated at about the same time, it is not surprising they received doses from the same batch, say members of SEAC.
What’s more, about one third of all British people vaccinated against polio since the first cases of BSE in 1986 received doses made from material that could theoretically have been contaminated. So an estimated 30 to 40 of the 113 vCJD patients identified to date would have received a potentially contaminated dose.
SEAC also stresses that polio vaccine distributed in the UK today is made using bovine material from Australia, New Zealand, the US or Canada – countries free of BSE. This means there should be no risk at all of contracting vCJD from current batches of oral polio vaccine.
In 1989, the government introduced legislation banning the use of British bovine material in the production of vaccines for the UK. But this covered only injectable vaccines. In 2000, the ban was extended to oral vaccines.
Groups that represent the families of vCJD patients say a full investigation into whether the vaccine could have caused infection in the two Southampton patients must be carried out.
