Why is there such a range in the number of deaths from Covid -19 between countries? A study of the data across 21 industrialised countries reveals a wide discrepancy. Preparedness and the point at which countries went into lockdown were key factors says Epidemiologist Jonny Pearson- Stuttard

Recurring illnesses which show up sometimes months after a Covid -19 infections are being more commonly reported. The Uk’s National Institute for Health research has launched a major initiative to better understand this long term effect of the disease, Candace Imison tells us more.

And another reported case of Covid 19 reinfection raises questions about widely held beliefs on immunity Microbiologist Sarah Pitt helps us separate the science from the fiction.

We also take a look at a black hole as it swallows up a star or at least at what’s detectable. Katy Alexander has trained radio telescopes at this distant event.

Curious CrowdScience listeners have suddenly been struck by the oddity of their behaviours. Elise ponders why she blushes. Thankfully, listener David is a vascular surgeon and knows a thing or two about blushing, as he performs operations on people debilitated by constant red-dening. He has some answers for us, but asks why did blushing evolve?

In the past, red cheeks have been linked to necrophilia, repressed cannibalism, and even a de-sire for men to experience menstruation! Thankfully, research has come a long way since then, as blushing experts Peter de Jong and Corine Dijk explain.

Scientists believe that it evolved as a nonverbal signal to show someone you’re sorry or that you care about what they think. This would have important for our survival in the group, en-suring we didn’t get into a fight or get kicked out the group.

Anand Jagatia gets to grips with blushing and other bodily behaviours – including a question from Thai listener Nitcha who wonders why we yawn as well as a question from Mohamed in Ghana and Biana in Trinidad and Tobago who both asked why people scratch their heads when they think. To answer these questions, Anand’s joined by yawning researcher Andrew Gallup and Sophie Scott as well as body language expert Blanca Cobb.

[Images: Getty Images]