Here are several good articles on the topic. All of these take quite a bit of effort to digest, but are informative:
- January 2021:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7790223/ - January 2020:
https://www.thelancet.com/journals/langlo/article/PIIS2214-109X(19)30490-5/fulltext - January 2020:
https://www.thelancet.com/journals/langlo/article/PIIS2214-109X(19)30453-X/fulltext - December 2003:
https://pubmed.ncbi.nlm.nih.gov/14641844/