Nasal flu spray offers best protection for babes and toddlers

May 2 2006

According to one of the largest comparisons of flu vaccines ever carried out, spraying a flu vaccine into the noses of babies and preschoolers is a far more effective method of protecting them than injections.

When 8,000 children under the age of 5 were given the spray flu vaccine (FluMist) it was found to be 55% more effective than an injection.

FluMist is a flu vaccine in the form of a spray and contains a live but weakened virus; it is currently only used in children over 5.

Manufacturer MedImmune Inc., which funded the new research, plans to seek government approval to sell FluMist for younger children as well.

Flu vaccines in injection forms use dead viruses and have never been as effective among under 5s as they have been with adults and children over 5.

Each winter, flu kills as many 36,000 Americans, most of them elderly and health experts say that children are the prime transmitters of the flu virus.

Vaccine specialist Dr. Robert Belshe of St. Louis University who led the new study believes children must be immunized in order to protect the elderly and frail from flu deaths.

For the study Belshe and an international team from 16 countries enrolled children aged 6 months to 5 years during the 2004 flu season.

Each child received a nasal spray and an injection shot, but only one was the real vaccine which allowed an unbiased comparison.

There was a safety concern when a small number of the youngest patients, age 6 months to 2 years, had an incident of asthma-like wheezing in the weeks following the first FluMist dose.

The risk was nevertheless slight with only 1 percent more children wheezing after FluMist than after the flu shot, and the reaction was temporary.

This could mean however that regulators may suggest that FluMist should be used only after age 2.

By the end of winter only 3.9 percent of nasal-spray recipients had become ill with influenza, compared to 8.6 percent of those who were given an injection.

What is more the nasal spray appeared to offer more protection as a slightly different strain than that which was present in the vaccine began circulating, and the nasal spray also offered protection against the new strain.

Scientists say the live-virus nasal spray is more effective than injection because it stimulates immunity in the nose and then the rest of the body.

Vaccine injections, which use dead viruses, do not stimulate this extra reaction in the nose.

The government is reportedly said to be examining whether FluMist could be effective against bird flu, as the extra nasal reaction may offer more protection against it.