Trump campaign says none of the "made-up stories" in Watergate journalist Bob Woodward's book are true.

Two China-based tour operators say tourists will soon be allowed to visit Samjiyon city in the north.

Covid-19 doesn't follow normal seasonal patterns, like other respiratory viruses – waves of infection can happen at any time of year.

There are striking parallels between the two syndromes – and scientists hope the link could help to unravel the mysteries of both.

With a new variant of the Sars-CoV-2 virus causing a spike in cases, it is showing just how much symptoms of the disease have changed since the pandemic began.

Studying the pathogens in sewage is helping scientists to track outbreaks of infectious diseases – and intervene before they escalate.

Like in many countries, misinformation about Covid-19 has circulated widely in Morocco during the pandemic, but much of it came from the US and Europe.

This winter's "tripledemic" is one of several recent odd trends among respiratory virus infections. Viruses, it turns out, can block one another and take turns to dominate.