The National Institute for Communicable Diseases has warned the public about a second wave of the H1N1 virus, commonly known as swine flu, hitting the country.

It says people should not let their guard down against the deadly virus, which has claimed the lives of several South Africans.

The most recent casualty is a KwaZulu-Natal doctor.

The institute's Adrian Puren says the viruses mutate and often launch fresh attacks.

"We're already seeing the so-called 'second wave' in the northern hemisphere. We need to make sure that we're prepared for the second wave and keep an eye out for what's happening in the northern hemisphere in terms of what the virus will do. In other words, will it continue to be mild or will it be the dominant virus?"

Swine Flu Special Report...