They were at a loss to know whether he had been scalped in battle, or enjoyed a natural immunity
from that belligerent infliction.
Nearly all had close contact with poultry, but scientists worry bird flu could mutate to a form easily spread among people, who have no natural immunity
. Many experts believe a pandemic will eventually occur.
Three years after a retrovirus to cure cancer becomes airborne, infecting the six billion people on Earth and producing rabies-like symptoms in almost every patient, military vir-ologist Robert Neville (Smith) - one of the lucky few with natural immunity
to the bug - continues his tireless work to engineer a cure.
It said the best policy was to leave badgers alone and allow them to develop natural immunity
These weak birds, forced to grow at artificially rapid rates and live in their own filth, have little natural immunity
against avian flu.
"But if we had a pandemic, the problem would be that our existing vaccines don't work against it, we would have to develop a new vaccine, and people don't have natural immunity
because it hasn't be around before," he said.
However today this means that 18 to 22-year-olds have not been able to build up a natural immunity
to the disease.
They point out that it encourages greater mother-infant bonding than does bottle feeding, while imparting some natural immunity
The treatment regime, called intermittent preventive treatment (IPT), protected the infants against malaria for at least six weeks after the end of treatment, showing that it had an ongoing protective effect and did not hinder the development of natural immunity
He added: "If we had a pandemic, the problem would be that our existing vaccine wouldn't work against it, we would have to develop a new vaccine, and people don't have natural immunity
because it hasn't been around before.
Sir Liam said there was a 'natural cycle' in which every 10 to 40 years the flu virus mutated into something for which there was no natural immunity
and it was a question of 'when, not if'.