"The World Health Organisation has recorded 184 human cases of the H5N1 strain of bird flu, all of them caused by contact with infected birds. That 103 of these have resulted in death indicates how dangerous this virus is, and no vaccine has yet been developed. For there to be a worldwide epidemic of H5N1 amongst humans, it would have to be possible for the virus to be passed easily from one person to another. Unlike normal influenza, H5N1 can only bind to receptors deep in the lungs. As a result, it cannot multiply in the upper respiratory system and thereby be transmitted by sneezing and coughing. So it cannot be transmitted easily between people. Influenza viruses can mutate, and thus possibly change the way in which they infect victims." Which of the following can be drawn as a conclusion from the passage above?

Correct answer: B. If H5N1 mutates, there is likely to be a worldwide epidemic amongst humans of this strain of bird flu.

• A. Unless a vaccine is developed, many more people will catch the H5N1 strain of bird flu.
• B. If H5N1 mutates, there is likely to be a worldwide epidemic amongst humans of this strain of bird flu.
• C. Unless H5N1 mutates, a worldwide epidemic amongst humans of this strain of bird flu is unlikely.
• D. If a person has no contact with birds, they are unlikely ever to catch the H5N1 strain of bird flu.
• E. None of the above

Last updated 3 September 2026