This is the VOA Special English Health Report.

In recent days there have been two seemingly hopeful pieces of news about bird flu. 

One involves a study by scientists at the Centers for Disease Control and Prevention in Atlanta, Georgia.  They combined a human influenza virus with the deadly H-five-N-one form of avian influenza. 

Ferrets react to flu viruses in ways similar to humans.

The researchers wanted to see if this combination virus, or hybrid, would spread easily among laboratory animals.  They injected the virus into ferrets.  These animals easily catch and spread human flu.  But they do not easily catch the H-five-N-one virus -- which so far is also true of humans.

In the study, as expected, human flu viruses spread easily among the ferrets.  But the researchers say the hybrid virus did not spread easily.  They even passed a hybrid virus through a series of ferrets.  But that did not result in genetic changes that would make the virus more aggressive.

One way for an animal virus to become able to pass easily from person to person is to combine with a human virus.  Scientists say hybrids led to the flu pandemics of nineteen fifty-seven and sixty-eight.  But they believe the so-called Spanish flu of nineteen eighteen might have jumped directly from birds to humans after some genetic changes. 

Julie Gerberding is director of the Centers for Disease Control.  She says the new findings do not mean the H-five-N-one virus cannot change into a form easily passed between people.  She says the findings suggest only that such a process is not simple.   The research appeared this week in the Proceedings of the National Academy of Sciences. 

Since two thousand three, the World Health Organization has recorded more than two hundred thirty human cases of the H-five-N-one virus.  Almost sixty percent of those people have died.

Last week GlaxoSmithKline said it was hopeful about tests of a vaccine to protect against the virus.  The British drug maker tested it in four hundred adults in Belgium. 

GlaxoSmithKline says the vaccine requires only a very small amount of adjuvant, so the company could produce larger supplies.  An adjuvant is a substance that helps a vaccine work better in the body. 

GlaxoSmithKline says it could have the vaccine ready as early as next year.  The company would need approval from governments.  And the vaccine might be of little use if a different virus causes the next pandemic.

And that’s the Special English Health Report, written by Caty Weaver.  Read and listen to our reports at voaspecialenglish.com.  I’m Steve Ember.