There are a few comments / questions about yeast in the cooments. According to this [1], quoting:

    Abdala, basado en la formulación de la proteína RBD (Dominio de Unión al Receptor) recombinante adyuvado en hidróxido de aluminio, emplea la proteína que se expresa en la levadura Pichia pastori, con un diseño que utiliza el RBD ACE 2, es decir, es el motivo que une al receptor y a través del cual el virus penetra a la célula e infecta al individuo.

Abdala, based in the formulation of the RDB protein (receptor binding domain) adjuvanted* recombinant* in aluminum hydroxide, employs / uses the protein that expresses in Pichia Pastori yeast, with a design that uses the RDB AC 2, meaning, is the motiv that unites the receptor and thru wich the virus penetrates the cell and infects the subject.

* & * I don't even know what these words mean in Spanish. I used G Translate for these 2 (I'm obviously way out of my pay grade here)

[1] https://instituciones.sld.cu/hospmiguelenriquez/2021/04/22/i...