Despite recent studies and case reports, the relevance of exposure to a resistant virus is still not well understood.

These tests may not be accurate if the resistant virus is less than 20% of the circulating virus.

You may be tested for infection with a resistant virus when:

They found that 9 children, or 18 percent, began producing viruses resistant to the drug within four days of starting treatment.

Kiso et al. suggest "a higher prevalence of resistant viruses should be expected" during a pandemic.

Other cases result when someone infected with a resistant virus transmits it to another person.

The woman had not previously taken Tamiflu, so concern has been expressed that she may have contracted an already resistant virus from someone else.

Transmission of resistant virus from one patient to another is suspected in both outbreaks.

Of the two isolates a subject from the placebo group had a resistant virus in cell culture to pleconaril.

Efforts to find effective drug combinations for people with highly resistant viruses are called salvage therapy.