While vaccine technology has changed greatly over time - resulting in vaccines which use attenuated or disabled viruses for more safety - some vaccinations still carry the live disease pathogen. This remains true for the smallpox vaccine.

Smallpox is generally considered eradicated. In most countries, vaccination programs against smallpox have all but disappeared. However, the September 11 terrorist attacks in 2001 renewed fears that such attacks could also involve the wide-scale release of deadly viruses or bacteria - including smallpox. Given the lack of current vaccination for smallpox (with the resulting lack of herd immunity), infection could have the same lethal consequences as when the virus was much more common.

However, eczema could pose a special problem for renewed vaccination.

Eczema, or atopic dermatitis, is an allergic condition that affects the skin. Patients have red, flaky and itchy patches of skin. The history of the vaccine shows that individuals with eczema have a higher rate of serious infection from the vaccine itself.

In the time period since active vaccination programs stopped, the eczema rate has been rapidly increasing, doubling twice over the last 30 years. This means that the rate of complication from a smallpox vaccination program could be much higher than it was in the past.

Dr Lisa Beck, associate professor of Dermatology and Medicine at the University of Rochester Medical Center said that as many as 20 per cent of children have eczema today. This contingent of patients would be at the highest risk of infection. Of children that develop a vaccine-related infection, as many as 20 per cent could die.

The threat is not simply to eczema patients who receive the vaccination. Historical records also show it is possible that individuals with eczema could acquire a life-threatening infection by coming in contact with the recently-immunized.

Recent incidents show that the historical records are accurate. In May of 2007, a US soldier who had been recently immunized for smallpox was sent home after his deployment was delayed. He then infected his two year old son, who had eczema. While the son survived, the infection was serious and highlighted the potential risk.

Source: Physorg.com