DNA measles vaccine breakthrough

Measles vaccination ineffective for infants

A measles vaccine which could save the lives of millions of infants has come a step closer, scientists say.

The vaccine involves injecting DNA into the body of the child, unlike traditional immunisations which use a weakened or killed version of the disease-causing organism.

A new measles vaccine candidate for immunisation of infants in developing countries ideally should be simple, inexpensive and heat-stable

Diane Griffin, Johns Hopkins University

Conventional vaccines are not effective in very young children because of their undeveloped immune systems. DNA vaccines do not have a threat of infection.

Though effective immunisation for children has existed since 1963, there are still a million deaths from measles each year because of the difficulty of vaccinating infants.

Attempts to immunise infants in the past have been disastrous - a formalin-inactivated prototype developed in the late 1960s led to a severe infection known as atypical measles.

But the scientists at Johns Hopkins University, in the US, say they have found a safe and effective alternative thanks to DNA vaccination, which is a recent advance.

Monkey model

They tested two DNA plasmid vaccines, encoding glycoproteins from the measles virus in a monkey model.

Antibody production resulted from the vaccination, protecting the animals from the measles virus.

There was no evidence of atypical measles in the monkeys.

Diane Griffin at the university's molecular microbiology and immunology department said in the journal Nature Medicine: "A new measles vaccine candidate for immunisation of infants in developing countries ideally should be simple, inexpensive and heat-stable.

"DNA vaccines meet these requirements and can induce immunity against a variety of infectious agents in animal models."

Dr Ann Arvin at Stanford University School of Medicine's department of paediatric infectious diseases said: "Although they hold much promise, DNA vaccines will rival the available live attenuated vaccines only when inoculation procedures are simplified and theoretical advantages for enhancing immunogenicity in early infancy are translated into practice."

Dr Elizabeth Miller, head of the immunisation division at the Public Health Laboratory Service, said the advance was an "interesting principle" but it would be years before it came into effect.

She added that if use of current vaccines in older children was maximised, there would be no risk of infection in infants as they would not be exposed to the illness.