Post-exposure Prophylaxis

The main purpose of the study is to evaluate the efficacy of a single dose of baloxavir marboxil compared with placebo in the PEP of influenza virus infection with respect to symptomatic, laboratory-confirmed influenza in participants who are household contacts (HHCs) of participants with influenza (index participants).

Occupational exposure to blood-borne pathogens, such as human immune-deficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV) for healthcare workers through contact with human blood and body fluids has become a major health concern as it poses a risk of transmission of these infectious agents. According to the World Health Organization (WHO) report, about three million HCWs are exposed to blood-borne pathogens each year, of which 170,000 are exposed to HIV infections, 2 million to HBV infections, and 0.9 million to HCV infections. Most of the time, healthcare providers get exposure through the splash of blood or other body fluids into the eyes, nose, or mouth or nonintact skin exposure, and percutaneous injury occurs as a result of a break in the skin caused by a needlestick or sharps contaminated with blood or body fluids

Post-exposure prophylaxis (PEP) using doxycycline 200 mg within 24 hours of unprotected sexual intercourse to prevent sexually transmitted infections has demonstrated a reduction in the incidence of chlamydial and syphilis infections and syphilis infection by 70% and 73% in men who have sex with men (MSM) undergoing pre-exposure prophylaxis prophylaxis (PrEP) for HIV. Other studies are underway or in development on doxycycline prophylaxis for bacterial STIs, which are particularly common in this population. Monitoring adherence to PEP is of great interest in guaranteeing the effectiveness of this strategy and to be able to assess the uptake of PEP among PrEP users. Among the many methods for assessing adherence, measuring drug concentrations is a more accurate measure of adherence than self-reporting. The therapeutic monitoring of doxycycline and the assessment of adherence have been described using plasma and hair samples, allowing estimation of intake over the last 3-4 days and 4 months, respectively. Nevertheless, these biological matrices present several limitations for application in clinical practice: reflecting the duration of exposure should be more in line with the frequency of visits (2 months), and the collection of hair samples may be difficult due to refusal or short hair. On the other hand, interpretation of the hair assay is limited by the degradation of doxycycline in this matrix, which could lead to underestimation of drug intake. By Therefore, new biological matrices are needed for more accurate assessment of doxycycline adherence in post-exposure prevention monitoring. The objective is to evaluate the pharmacokinetics of doxycycline in plasma, whole blood, dried blood spots (DBS), urine and hair after a single dose of doxycycline in men using oral doxycycline for post-exposure prophylaxis of sexually transmitted infections (syphilis or Chlamydia trachomatis) and having sex with men.