More or Less

As some countries rapidly roll out vaccination programmes, there have been concerns that increases in infection rates amongst vaccinated groups mean vaccines are less effective than we hoped, especially in the face of the feared Delta variant. Epidemiologist Dr Katelyn Jetelina from the University of Texas Health Science Centre School of Public Health explains why this isn’t what the numbers show – rather than decreasing vaccine effectiveness, increasing rates can be explained by a statistical phenomenon known as ‘base rate fallacy’. Presenter: Charlotte McDonaldProducer: Nathan Gower

June saw a brutal heatwave shatter a number of all-time temperature records in Canada and the Northwest of the USA. But when can we attribute new records to man-made climate change, rather than natural variation? Peter Stott, an expert in climate attribution at the UK’s Met Office, explains how climate change has dramatically increased the probability of seeing such extremes.Presenter: Tim HarfordProducer: Nathan Gower

The Delta Variant was first identified in India, fuelling a huge wave of cases and deaths. It is now spreading around the world, becoming the most dominant variant in many countries. This week we take a look at the numbers - where’s it spreading, how is this different to previous waves and what can be done to stop it?Tim Harford speaks to Professor Azra Ghani, Chair in Infectious Disease Epidemiology at Imperial College, London and John Burn-Murdoch, the chief data reporter at The Financial Times.

On the day the Government plans to drop the remaining Covid restirictions, Tim Harford and the More or Less team try to work out how long cases will continue to rise and whether we can be sure the link with deaths and hospitalisations has been broken. Is this “freedom day" or an unnecessary gamble with people’s lives?

In recent months, Twitter has rarely been out of the headlines in Nigeria. After it deleted a tweet by the country’s president, the Nigerian government responded by banning it altogether. In the media coverage of the story it has been commonly claimed that Nigeria has 40 million Twitter users – but could this really be true? We spoke to Allwell Okpi of the fact-checking organisation AfricaCheck.Also, which places have the best full vaccination rates in the world? Turns out, its some of the smallest. We run through the top five.Producer: Nathan Gower

To some on the internet, the cheap anti-parasitic drug Ivermectin is a potential wonder drug that could dramatically change the global fight against Covid-19. It has passionate proponents, from a small group of scientists to the more conspiratorially-minded. But with a scattered evidence base of varying quality, what - if anything - do we know for sure about Ivermectin? And is uncovering the truth a more complex process than some appreciate?With Gideon Meyerowitz-Katz from the University of Wollongong, Australia.Producer: Nathan Gower

The UK’s Covid cases are still rising and Scotland is being hit particularly hard - so are we speeding up our vaccination programme in response?Will many of the UK’s coastal towns, not to mention central London, be underwater in the next few years?Do the country’s poorest households really pay more than half their income in tax?What are the top five places with the best vaccination rates in the world? The answers may surprise you.We speak to Tom Chivers, a science journalist who has written a book called “How to Read numbers” with his cousin the economist David Chivers.

The podcast dives into the 400th anniversary of the Mayflower voyage, a pivotal event in U.S. history. It reveals how millions today can trace their lineage to the original 102 passengers. The discussion includes the harsh realities faced during the voyage and the surprising mathematics behind descendant relationships. The concept of pedigree collapse is explored, showing how interconnected modern families are to historical figures. A lighthearted twist concludes with a quirky estimate linking Mayflower descendants to the number pi.

The Delta variant is behind the big increase in the number of new Covid 19 cases in the UK since April. We take a look at what impact vaccines have had on infections, hospitalisations and deaths.Chris Packham told viewers on the BBC’s Springwatch that blue tits eat 35 billion caterpillars a year. We get him onto the programme to explain.How much does Type 2 diabetes cost the NHS a year? While exploring a dubious claim we find out why its hard to work that out.Is it true that on in two people will get cancer? We’ve looked at this statistic before but listeners keep spotting it on TV.We also ask: if the SarsCov2 RNA is 96% similar to the RNA of a virus found in bats - is that similar, or not?

To find out where a virus comes from, researchers compare it to other viruses to try to trace its origin. This leads to claims like SARS-CoV-2 is 91 or even 96% similar to other known viruses. But what does that really mean? Tim Harford talks to the virus ecologist Marilyn J Roossinck.