Current understanding is that the practice isn't
harmful (safety) and
may benefit (efficacy), the two key concerns of drugs trials. See (from August 12, 2021):
https://www.msn.com/en-us/news/world/what-we-know-so-far-abo...
WHO was recommending against as of July, 2021, though based on a lack of evidence rather than evidence of harm or lack of efficacy.
https://www.msn.com/en-us/health/medical/who-warns-against-m...
The question is being investigated currently:
https://www.nih.gov/news-events/news-releases/nih-clinical-t...
"We don't know" alone is not a valid reason for discouraging a practice where there's no clear indication of harm and where understanding is being actively developed. There's an absolutely valid basis for taking a probablistic risk-based approach based on likely benefits vs. costs.
