Still, some concerns have been raised about the drug, not least among them the potential for mutation of the virus--there are theories that the preventative drug will encourage the virus to become stronger. To help curb that possibility, the FDA says "Truvada's manufacturer, Gilead Sciences, Inc., is required to collect viral isolates from individuals who acquire HIV while taking Truvada and to evaluate these isolates for the presence of resistance." In other words, Truvada will, you know, watch the situation closely.