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New Flu Vaccine Outperforms Shots

Immunizations: Nasal spray protects against common strains, plus the puzzling A/Sydney variety. It's proving more effective than conventional inoculations.

October 05, 1998|THOMAS H. MAUGH II | TIMES MEDICAL WRITER

A new influenza vaccine that is administered through the nose rather than by a needle is more effective than the conventional flu shots, researchers reported late September in San Diego.

The new vaccine not only provided 100% protection against the flu varieties included in it, but also provided significant protection against the flu variety called A/Sydney that sprang up suddenly, confounding flu experts, Dr. Robert Belshe of St. Louis University in Missouri told a meeting of the Interscience Conference on Antimicrobial Agents and Chemotherapy.

Belshe speculated that the nasal vaccine, called FluMist, worked better than conventional vaccines because it incorporates a weakened influenza virus rather than dead ones. When sprayed up the nose, the weakened virus causes a harmless infection and produces new copies of itself, increasing its stimulation of the immune system.

Designing a flu vaccine is something of a crapshoot because the influenza virus mutates rapidly. Each year, government scientists choose the three strains of influenza virus that they believe will predominate in the upcoming flu season, and these are used in preparing a vaccine.

Last year, the experts failed to choose A/Sydney, and many people who received the conventional shots developed flu anyway.

Belshe vaccinated 917 children with FluMist, developed by Aviron of Mountain View, and 414 with a placebo. He reported that the nasal vaccine provided 100% protection against the three strains included in the preparation and 86% protection against A/Sydney.

"What happened last year with A/Sydney is very exciting," said Dr. Dominick Iacuzio of the National Institute of Allergy and Infectious Diseases, which sponsored the test. "This was a true test, and the vaccine passed with flying colors. Right now, it looks like the spray has advantages."

Aviron hopes FluMist will be widely available for the 1999-2000 flu season.

In other studies presented at the meeting:

* Infants who die from sudden infant death syndrome (SIDS) are more likely to have been infected by cytomegalovirus than those who do not, German researchers reported.

Having children sleep on their stomachs has previously been linked to causing the disease, but campaigns to have parents place them on their sides or backs have not eliminated the problem, suggesting there are other causes as well. Some reports have hinted that respiratory infections in the period before death are common in SIDS victims.

Dr. Ulrich Heininger and his colleagues at the University of Erlangen studied SIDS victims to look for traces of viral infections, comparing them with carefully matched healthy children. They found traces of most common respiratory viruses in the same percentage of SIDS victims as in healthy children.

The only exception was cytomegalovirus, which was present in 7.1% of the control group, but in 17.7% of the SIDS victims.

Cytomegalovirus is transmitted from mother to child during childbirth in about 1% of pregnancies. About 1% of children and adolescents also contract it from other sources each year. It is known to cause liver damage and hearing impairment, and Heininger speculates that it may also cause SIDS through some as-yet unknown mechanism.

*

* Government scientists have found that the prevalence of herpes simplex virus type 1 (HSV-1), which causes painful cold sores, has remained constant over the last 13 years, with more than 135 million Americans older than 12 carrying the virus.

HSV-1 can be sexually transmitted to cause genital herpes infections and can result in life-threatening infections when transmitted to infants, but it also seems to protect its carriers against infection by the more serious HSV-2, which causes most genital infections.

Last year, researchers from the U.S. Centers for Disease Control and Prevention reported that the prevalence of HSV-2 had increased 30% in 13 years. Some scientists had speculated that decreased HSV-1 infections had allowed the increase in HSV-2, but that is clearly not the case, said Dr. Julia Schillinger of the CDC.

Schillinger and her colleagues took blood samples from more than 13,000 people and assayed them for types 1 and 2 herpes viruses. She found that more than 50% of Americans had been infected by HSV-1 by their mid-20s. By the time they reached their 70s, more than 90% of Americans had been infected.

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