> I agree this is about quality control and it is extremely unlikely to affect vaccine efficacy. (If anything, it would improve vaccine efficacy.)

I don’t think you can say this with much certainty, if the viruses either regained or never lost E1, it’s also possible that the same is true with E3 which modulates immune response.

Also, either of these genes could’ve replaced the Coronavirus spike protein.

I will try to find the source again, however I would read todos os lotes as saying that there are detectable replicant viruses.

Replicant viruses do not carry the spike protein, they don't contribute to antigen protection.

> Replicant viruses do not carry the spike protein, they don't contribute to antigen protection.

Are you sure? Do you mean that all of them must have had recombination that added the E1 gene and dropped the spike protein?

Indeed. So if a virus is able to replicate it must have a replication-competent E1 gene which normally encodes for the spike