But if race is a social construct, how would this work?

The Independent warns that "World must prepare for biological weapons that target ethnic groups based on genetics, says Cambridge University." From the article:

     Biological weapons could be built which target individuals in a specific ethnic group based on their DNA, a report by the University of Cambridge has warned.

     Researchers from Cambridge’s Centre for the Study of Existential Risk (CSER) said the government was failing to prepare for ‘human-driven catastrophic risks’ that could lead to mass harm and societal collapse.

     In recent years advances in science such as genetic engineering, and artificial intelligence (AI) and autonomous vehicles have opened the door to a host of new threats.

* * *

     “In a particularly bad case, a bio-weapon could be built to target a specific ethnic group based on its genomic profile”