Blood or sexual exposure: initial tests and follow-up

• Exposure less than 48 hours ago: refer without delay to the emergency department or the referral service to discuss post-exposure prophylaxis (PEP). The tests must never delay it.

Laboratory tests of the exposed person

• HIV serology
• Hepatitis C serology
• Hepatitis B serology: HBsAg, anti-HBs, anti-HBc (unless immunity documented; anti-HBs alone in a vaccinated person whose titre is unknown)
• ALT
• Serum creatinine with eGFR (if PEP)if neededOnly if PEP is prescribed (tenofovir) ^[2,3].
• β-hCG (if PEP in a woman of childbearing potential without contraception)if neededWoman of childbearing potential without contraception, if PEP is given ^[2,3].

At 6 weeks after exposure

• HIV serology (without PEP, source of unknown HIV status or with detectable viral load; occupational accident: in all cases)if neededWithout PEP, if the source’s HIV status is unknown or the source is living with HIV with a detectable viral load ^[3]. Occupational accident: the order of 27 May 2019 provides for this test at 6 weeks with or without PEP, then a third at 12 weeks if PEP was prescribed ^[7].
• ALTif neededSource viraemic for HCV (RNA positive): early follow-up test ^[2,3]. HCV RNA is covered after a needlestick injury (sampling, injection); after a mucosal splash, it falls outside the wording of the French laboratory fee schedule (NABM) ^[4].
• HCV RNA (source HCV RNA positive)if neededSource viraemic for HCV (RNA positive): early follow-up test ^[2,3]. HCV RNA is covered after a needlestick injury (sampling, injection); after a mucosal splash, it falls outside the wording of the French laboratory fee schedule (NABM) ^[4].
• HCV RNA (if source of unknown HCV status, or anti-HCV positive without RNA available, after a needlestick injury)if needednon-French guidelineThe CDC (2020) test for HCV RNA at 3-6 weeks as soon as the source is RNA positive, anti-HCV positive with no RNA available or not testable, for example after a needlestick from a needle discarded in a bin ^[11]. The HAS (French National Authority for Health) and the GERES (French occupational blood exposure study group) provide for it only for an RNA-positive source, without explaining why in their text ^[2,3]. The NABM covers it after a needlestick injury if the source is infected or of unknown status ^[4].

At 12 weeks after exposure

• HIV serology (if PEP; possible from 10 weeks)if neededOnly after PEP (possible from the 10th week) ^[3,7].
• Hepatitis C serology (unless source known to be HCV negative)if neededHCV-positive source or source of unknown HCV status ^[3].
• Hepatitis B serology: HBsAg, anti-HBs, anti-HBc (non-immune person, source HBsAg positive or unknown)if neededExposed person not immune (anti-HBs negative, not vaccinated) and source HBsAg positive or of unknown status ^[2,3].
• ALT

At 6 months after exposure

• Hepatitis C serology (if source infected with HCV and tests negative so far)if needednon-French guidelineAfter a high-risk exposure, the United Kingdom concludes at 12 weeks with HCV RNA or antigen, or at 6 months with antibodies ^[9]; the CDC repeat the antibodies at 4-6 months, as RNA may be transiently undetectable and seroconversion occurs on average 8 to 11 weeks after exposure ^[11]. The HAS concludes at 12 weeks to simplify follow-up, while accepting additional checks if the source is HCV RNA positive ^[2].
• HBsAg (if non-immune person, source HBsAg positive and anti-HBs still < 10 IU/L at 12 weeks)if needednon-French guidelineThe United Kingdom checks HBsAg at 6 months if anti-HBs remain < 10 IU/L at 12 weeks ^[9]; the United States and Australia also follow the non-immune person up to 6 months ^[10,12]. The HAS concludes at 12 weeks to simplify follow-up, while accepting additional checks if the source is HBsAg positive ^[2]. The single marker is billed as the full serology (procedure 4500) ^[4].

• Exposure less than 48 hours ago: refer without delay to the emergency department or the referral service to discuss post-exposure prophylaxis (PEP). The tests must never delay it.

Laboratory tests of the exposed person

• HIV serology
• Hepatitis B serology: HBsAg, anti-HBs, anti-HBc (unless immunity documented or status already known)
• Hepatitis C serology
• Syphilis serology
• Chlamydia trachomatis and gonococcus NAAT (PCR), 1 site (self-collected vaginal sample or first-catch urine if penis)
• Chlamydia trachomatis and gonococcus NAAT (PCR), 2 sites (plus anal or oro-genital intercourse)if neededSites according to the exposure: pharynx if oro-genital intercourse, anus if anal intercourse ^[2]. Replaces the 1-site PCR (procedures cannot be combined) ^[4].
• Chlamydia trachomatis and gonococcus NAAT (PCR), 3 sites (genital, anal and pharyngeal)if neededGenital, anal and oro-genital exposure ^[2]. Replaces the 1-site PCR (procedures cannot be combined) ^[4].
• ALT (if PEP)if neededOnly if PEP is prescribed ^[2].
• Serum creatinine with eGFR (if PEP)if neededOnly if PEP is prescribed ^[2].
• β-hCG (woman of childbearing potential without contraception)if neededWoman of childbearing potential without contraception, at the first visit and whenever she wishes ^[2].

At 6 weeks (without PEP), 10 weeks (after PEP) or 12 weeks (risk of hepatitis)

• HIV serology
• Syphilis serology
• Chlamydia trachomatis and gonococcus NAAT (PCR) on the exposed site(s)
• Hepatitis B serology: HBsAg, anti-HBs, anti-HBc (non-immune person; at 12 weeks)if needed“Hepatitis B risk”: person not immune to HBV; check at 12 weeks ^[2].
• Hepatitis C serology (risk of hepatitis C; at 12 weeks)if needed“Hepatitis C risk”: traumatic anal practice, source who injects drugs, chemsex, source living with untreated HCV; check at 12 weeks ^[2].
• ALT (risk of hepatitis; at 12 weeks)if neededRisk of hepatitis B or C (see above) ^[2].
• Anti-HAV IgM (oro-anal intercourse)if neededExposure at risk of hepatitis A (oro-anal intercourse): IgM for acute hepatitis ^[2].
• β-hCG (woman of childbearing potential without contraception)if neededWoman of childbearing potential without contraception, whenever she wishes ^[2].

Laboratory tests of the source person, to be offered to them

• HIV serology
• Hepatitis B serology (HBsAg)
• Hepatitis C serology
• HCV RNA (if HCV serology positive)if neededPositive HCV serology: looking for viral replication is an NABM indication for HCV RNA ^[4]; a viraemic source brings forward the exposed person’s follow-up to 6 weeks ^[2,3].
• HCV RNA straight away (if injecting drug use in the last 4 months or risk that cannot be assessed)if needednon-French guidelineIn a source with recent risk, serology may still be negative. The CDC (2020) then request HCV RNA from the first test, RNA being detectable from 1 to 2 weeks ^[11]; the United Kingdom accepts HCV RNA or antigen in place of antibodies in a high-risk source ^[9]. The HAS and the GERES do not mention it: they start from the source’s status, and the NABM reserves the procedure for the situations in its wording ^[2,3,4].
• Source living with HIV: obtain their latest viral load, or do one urgently if it is more than 6 months old or if adherence is in doubt (with the referral service).