It's possible to overdose, so I don't think they would do that. I suppose using incredibly small amounts might be effective without fear of harming people, but that would be very risky, especially to the young. It would be next to impossible to know how much would be ingested.
"Commonly used on holidays in malaria prone destinations, chloroquine and hydroxychloroquine will not be over familiar to the emergency physician. However, it is one of the leading causes of drug overdose in malaria prone countries and also the occasional toddler has managed to consume the grandparents lupus or rheumatoid arthritis medication leading to lethal consequences."
litfl.com/chloroquine-hydroxychloroquine-toxicity/