An update on the Pfizer vaccine for Covid-19, the lotto likelihood of sequential winning numbers, why swallows congregate around motorway bridges, the logistics of keeping the Covid-19 vaccine cold, and why is it dark in space? Also, why is there a Covid-19 vaccine in 10 months but no HIV vaccine after 4 decades, would we still have tides without the Moon, and why is the Moon white since the sky is blue? Join Dr Chris and 567 CapeTalk's Kieno Kammies for the answers... Like this podcast? Please help us by supporting the Naked Scientists