Mutated Covid-19 strain confirmed in Japan as case tally hits record high
As discussed on TWiV yesterday, B.1.1.7 isn&#x27;t a &quot;strain,&quot; which has demonstrably different biological properties, but is still considered a &quot;variant.&quot;<p><a href="https:&#x2F;&#x2F;www.microbe.tv&#x2F;twiv&#x2F;twiv-697&#x2F;" rel="nofollow">https:&#x2F;&#x2F;www.microbe.tv&#x2F;twiv&#x2F;twiv-697&#x2F;</a><p>Any biological differences are theorized solely from the genome at this point. In the episode, Racaniello is at pains to point out that genomic differences alone don&#x27;t imply biological differences in say transmission, and things like founder effects might also explain the variant&#x27;s prevalance. We simply don&#x27;t know yet.<p>There&#x27;s a neat cautionary example at 35:10 which I&#x27;ll try to summarize here. Polio was endemic, with low incidence, for thousands of years. Around 1900 it went from endemic to epidemic. Why? Did it suddenly mutate into a deadlier or more transmissable strain? While we don&#x27;t have polio sequences from before and after 1900 to compare, we do know that rapid improvements in sanitation delayed exposure to the polio virus. Babies were now encountering the virus after maternal antibodies to it had waned! And it turns out this adequately explains the spike in polio a century ago.<p>Goes to show how complex the dynamics of these systems can be!