26 Aug addendum to Episode 165 on inactivated vaccines

Dear colleagues,

Science goes fast.  To my overview of this morning, this important preprint should be added:  Thiago Cerqueira-Silva Effectiveness of Vaxzevria (= Astra-Zeneca) and CoronaVac vaccines in Brazil medRxiv 25 Aug 2021.  As you can read, this is a nationwide retrospective comparison on tens of millions.  I summarize the main findings in the table.

During the study period (Jan-June), the gamma variant was most prevalent in Brazil

• As expected, both vaccines are active, but clearly Vaxzevria > CoronaVac.
• In elderly over 90 (not at lower ages) both vaccines lose a lot of activity

Since Vaxzevria = Covishield, Ep 165-30 suggest that a heterologous combination may be superior.