Study authors purchased >10,000 samples of Artemisinin combination treatments in 6 malaria endemic countries and analysed them in a lab. They found that the number of falsified drugs was significantly lower than previously thought (highest was seen in equatorial Guinea at 8%). However, the prevalence of substandard drugs ranged from 6-37%.
“Whilst the numbers of falsified drugs were either none or less than 8 % but the substandard drugs were found between 6.0 and 37 % in all countries where studies were conducted”
Kaur, H., Clarke, S., Lalani, M., Phanouvong, S., Guérin, P., McLoughlin, A., … Schellenberg, D. (2016). Fake anti-malarials: start with the facts. Malaria Journal, 15(1), 86. doi:10.1186/s12936-016-1096-x