‘Doxy PEP’, or doxycycline post-exposure prophylaxis, is where a common antibiotic is given to someone shortly after having unprotected sex to avoid the chance of them getting an STI like chlamydia, gonorrhea, or syphilis. It’s an idea being put forward by the Centers for Disease Control and Prevention in the USA to cut STI rates. If their proposal is rolled out across the country, it would be the first national guideline recommending Doxy PEP for certain individuals, anywhere in the world. Claudia Hammond speaks to Professor Annie Luetkemeyer about the evidence for Doxy PEP, and hears from a Canadian man who had syphilis. BBC Health and Science Correspondent James Gallagher brings Claudia new research on the most effective COVID-19 disease trackers. And a study from Sweden which could help us understand why people live beyond 100, by analysing their blood. And they hear from people around the world who have come together to talk about grief. The New Normal is a charity that has its roots in a barber shop in the UK when Ben (the barber) and Jack (his client) realised they shared the experience of losing their fathers. They set up a support group where people could share honest stories about grief. Now the charity have members across the globe who meet online and share stories about losing the people they love. Presenter: Claudia Hammond Producer: Clare Salisbury Editor: Erika Wright