you are understanding it correctly, if they are well matched (if lucky) they have at best 40-60% efficacy, if they are NOT well matched (if not lucky) their eff

you are understanding it correctly, if they are well matched (if lucky) they have at best 40-60% efficacy, if they are NOT well matched (if not lucky) their efficacy is somewhere between 0-40%, simple as that, but these pro-vaxxers will ignore science if it doesn't suit their interest