HCQ
Current recommendations for treatment of chronic Q fever are 100 mg doxycycline twice per day combined with hydroxychloroquine three times per day at 200 mg per dose for at least 18 months [23,33]. Two daily 100 mg doses of doxycycline have been shown to result in serum concentrations of 2-5 mg/L [34,35]. There is evidence that doses resulting in serum concentrations higher than 5 mg/L can lead to faster decline in anti-C. burnetii antibodies [36], but controlled studies evaluating doxycycline dosage have not been reported.
The usage of doxycycline plus hydroxychloroquine has reduced the time of treatment in chronic Q fever patients to 18 months for those with native heart valves and 24 months for patients with prosthetic valves. Although still a very long treatment period for a bacterial disease, the use of hydroxychloroquine has reduced treatment times that were previously as long as five years [29]. Long-term treatment with doxycycline and hydroxychloroquine are not without potential complications. Both of these drugs can cause photosensitivity [37], and long term use of hydroxychloroquine can lead to retinopathy [38]. A baseline ophthalmic evaluation is recommended for patients beginning long term hydroxychloroquine with follow-up examinations every six months while on therapy [23,38]. Allergic reactions to both drugs have been reported [28].
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For these reasons, the US biological weapons program tested C. burnetii on human subjects in the 1950’s and 1960’s as part of “Project Whitecoat” [6,44]. In these studies, C. burnetii was found to be able to infect humans at a very low dose of less than 10 organisms, and aerosol dispersal was effective for human infection [6]. Although use of C. burnetii as a weapon would not be expected to cause widespread fatalities, it is thought that significant impairment of physical activity could be achieved, along with associated alarm in the population and significant long-term morbidity for a subset of victims [43]. Recent advances in microbiological techniques make it conceivable that C. burnetii could be modified for greater virulence or made to have antibiotic resistance [45].
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4608426/