This 19th-Century killer is making a comeback – and with protection from the whooping cough vaccine waning over time, the hunt is on for something longer-lasting.

West Nile virus is spreading across the US and Europe. This deadly disease has been around for decades, but there is still no vaccine and no cure in humans.

Scientists are turning to a controversial approach to test new vaccines and treatments by deliberately infecting volunteers with potentially deadly viruses, parasites and bacteria.

There is concern about a new strain of the disease that has been spreading in parts of Africa.

The virus that causes mpox was first discovered at the end of the 1950s, but it has undergone changes in the past four years that allow it to pass between humans more easily.

The process of making vaccines for parasites is extremely challenging – but scientists might be on the cusp of major breakthroughs.

For decades, it was thought that not vaccinating children against chickenpox would reduce the risk of adults developing shingles – but now this is being questioned.

Scientists believe mRNA vaccines – which have played a crucial role in our fight against Covid-19 – could solve a number of health issues for humans.