New versions of the H5N1 virus are increasingly adept at spreading. Suggestions to either let it rip in poultry or vaccinate the birds could backfire.

The document notes that the delta variant, which was first detected in India, causes infections that are more contagious than the common cold, flu, smallpox and Ebola virus.

Read current news and medical research on influenza A, influenza B, including symptoms, vaccines and treatments for flu viruses.

Your guide to the most essential developments in life sciences.