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News that at least three new variants of SARS-CoV-2 have emerged in three separate continents have sent a chill throughout the scientific community. All viruses mutate but the speed and scale of the changes and the fact they occurred independently, is seen as a wake-up call.

Genetic sequencing in South Africa first raised the alarm about the version of the virus that was racing through populations in the Eastern and then Western Cape.

Scientists at the country鈥檚 KwaZulu-Natal Research and Innovation Sequencing Platform, KRISP, were struck by the sheer number of genetic mutations, many of which were on the all-important spike protein. This is where the virus binds to human cells and where neutralising antibodies, our immune system鈥檚 defences, also mount their defence. Any changes there, researchers knew, could be bad news.

Genetic sequencers in the UK also identified a new lineage which shares just some of the mutations in the South African variant. Named B.1.1.7 this version tore through populations in the South East of England and is now the dominant strain throughout the country and beyond. Latest estimates suggest is between 30 and 50% more infectious, although exactly how it is more transmissible is still being worked out.

In Brazil too, news earlier this month of another troubling variant, the P.1. tearing through populations in Manaus, the capital of Brazil鈥檚 Amazonas state, where so many were infected in the first wave of the pandemic. Like the version identified in South Africa, this variant also has mutation called E484K on the all-important spike protein. This could make the virus better at evading antibodies, with huge implications for re-infection rates and the new vaccines.

Claudia Hammond and her expert panel consider what the new shapeshifting virus means for the global goal of herd immunity and an end to the pandemic. And they answer your questions. Please do keep your virus queries coming in to the.evidence@bbc.co.uk and your question could be included in the next programme.

Claudia鈥檚 guests include Dr Richard Lessells, infectious diseases specialist from the University of KwaZulu-Natal in South Africa and part of the team that identified the South African variant; Dr Muge Cevik, clinical lecturer in infectious diseases and medical virology at the University of St Andrews in Scotland and a member of the UK鈥檚 expert committee NERVTAG (New and Emerging Respiratory Virus Threats Advisory Group); Dr Shane Crotty, Professor for Infectious Disease and Vaccine Research at la Jolla Institute for Immunology, University of California San Diego in the USA and Dr Margaret Harris from the World Health Organisation in Geneva.

Produced by: Fiona Hill, Samara Linton and Maria Simons
Editor: Deborah Cohen
Technical Support: Donald McDonald and Tim Heffer