Smallpox vaccine 'infects' baby

The baby caught the virus through breastfeeding

A baby showed signs of smallpox vaccine virus exposure after being breastfed by the wife of a US soldier given the jab.

The unusual case - which happened in May 2003 - was confirmed in a report by the US Centers for Disease Control.

The unnamed soldier had a "major reaction" to the vaccine - but continued to sleep with his wife, who carried on breastfeeding their baby.

The US launched a vaccination programme despite fears over side effects.

The smallpox vaccine contains a live virus, which means there is the potential for it to spread to others.

It is not the smallpox virus itself, but another related virus called vaccinia, which causes a much milder version of the illness.

Although it is not contagious in the same way as influenza or a cold, normally the sore that forms at the vaccination site is covered and those given the vaccine warned about the potential for the virus to spread by contact with it.

Tongue sores

The solider's wife developed sores near her nipples approximately a week after her husband was vaccinated.

Two weeks later, sores appeared on the infant's face and tongue. No information about its recovery was released by the CDC.

The CDC report urged breast-feeding mothers living with people vaccinated against smallpox to be aware of the potential risk to their babies.

There have been 18 reported cases of the accidental transmission of vaccinia since December 2002 - although this is the first reported "third hand" passing of the virus.

Vaccinated patients are told to wash their hands regularly and limit contact with babies.

The US smallpox vaccination programme is the most extensive in the world, and was set up in response to the threat that the virus - eradicated in its wild form in the 1970s - could be used in biological warfare or terrorism.

Approximately 500,000 key workers were to be offered the jab initially - with plans to expand the programme later in 2003.

However, a relatively high proportion of those given smallpox vaccine will have severe reactions to the jab - and many experts predicted that vaccinating so many people would inevitably lead to dozens of deaths.