related_tweet: @woodyuk69 @petemorristwit flu antigenically drifts/shifts, covid-19 does not &amp; it has a proof reader in its polymerase chain! hence, all covid-19 variants are still &gt;99% same as wuhan sequence, flu mutates 4x faster &amp; drifts so far it can "reassign" with another variant, creating new "strain" v dangerous