related_tweet: @peterofperth @jockalexander1 @esunachimba @aussieavidread @nswhealth but you miss the point, there are still plenty of people for delta to infect in australia, as only 11.5% of the population have had covid, so natural immunity is not a significant factor.
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  it is higher transmissibility of omicron and residual vaccine induced immunity to delta