On November 14, 2022, a 33-year-old healthy female HCW was exposed to monkeypox virus through a needlestick (26G needle) injury on the left index finger during aspiration of an infected patient’s vesicle. The HCW wore personal protective equipment consisting of a disposable gown, double gloves, and powered air-purifying respirator. Bleeding occurred after the injury, and povidone-iodine was applied to the puncture site ≈20 min after the incident. Within 20 hours after injury, the HCW received a third-generation smallpox vaccine (single-dose, subcutaneous injection of JYNNEOS; Bavarian Nordic A/S, https://www.bavarian-nordic.com) as postexposure prophylaxis. The HCW had no history of smallpox vaccination, exposure to monkeypox virus, or recent sexual contact and had not traveled abroad.

Figure

Figure. Progression of skin lesion caused by occupational transmission of monkeypox virus to a healthcare worker in South Korea. The healthcare worker was infected in the left index finger with monkeypox...

On November 17 (day 1), the HCW noticed a small papule at the needlestick site (Figure, panel A). On day 2, the papule increased in size; the HCW was admitted to the hospital isolation ward, according to Korea Disease Control and Prevention Agency policy for mpox. We performed monkeypox virus-specific PCR on blood samples and oropharynx and nasopharynx swab samples collected from the HCW. All samples were PCR-negative for monkeypox virus.

On day 6, the lesion was slightly larger and had a central umbilication (Figure, panel B). We aspirated the lesion, and PCR results for the aspirate were positive for monkeypox virus. We repeated testing of blood samples and oropharyngeal and nasopharyngeal swab samples, and PCR results for those samples were negative. Monkeypox virus transmission was presumed to be occupational because no other risk factors were identified.

On day 8, a new lesion appeared immediately above the initial lesion and began to progress (Figure, panel C). Pain at the lesion site was severe; the numeric rating scale (12) score was 8 because of neuralgia. The HCW described a sharp pain as “the feeling of being cut with a knife” that disrupted sleep. Although no disseminated lesions were present, because of the pain intensity and local spread of infection around the initial lesion, the attending infectious disease specialist prescribed tecovirimat starting on day 9 (10 days after smallpox vaccination), which substantially alleviated the pain. By day 16, the pain was almost completely gone.

On day 18, the lesions formed a crust (Figure, panel D) and were partially debrided 4 days later (Figure, panel E). PCR of the debrided skin specimen was positive for monkeypox virus. On day 25, the crust was completely debrided. and a necrotic scab remained underneath the devitalized tissue at the puncture site (Figure, panel F). Because mpox lesions developed after postexposure vaccination, the HCW did not receive a second dose of smallpox vaccine, which was scheduled for 28 days after the first dose. PCR of a lesion site sample yielded positive results for monkeypox virus, but the possibility of virus transmission was low, and clinical progress was stable. Consequently, we discharged the HCW under the guidance of an infectious disease specialist. After the patient was discharged, the tissue around the puncture site recovered completely by day 34 (Figure, panel G), and the scab was completely eliminated by day 40 (Figure, panel H).

We conducted a literature review to evaluate the status of and response to monkeypox virus infections among HCWs during the 2022 outbreak (Table). Transmission of monkeypox virus occurred through needlestick injuries in 5/8 cases; initial lesions developed at the puncture sites in each of those cases. The median incubation period was 5 (range 3–10) days, which was slightly shorter than the previously reported 7- (range 3–20-) day incubation period (3). The patient we report did not have disseminated or severe mpox. However, after administration of tecovirimat, symptoms (especially pain intensity) improved substantially and rapidly.

As recommended by WHO (1), 3 HCWs with needlestick injuries, 2 from the literature (5,8) and the HCW in the case we report, received a third-generation smallpox vaccine promptly after needlestick injury, and only local skin lesions developed at the site of inoculation without generalized illness. However, additional reports from the literature showed that HCWs without postexposure vaccination had substantially disseminated lesions; among those, 2 HCWs (6,7) were infected by needlestick injuries. Lesions developed on the hands and wrists of the other 2 HCWs, and the mode of transmission was likely fomite contact with bare skin. The HCW from California (10) was immunocompromised and worked in a clinic where patients with mpox regularly visited; unrecognized exposure and spread might have occurred through respiratory droplets.

On the basis of our case report and literature review, we recommend the following procedures for HCWs who treat patients with mpox. First, the literature review revealed differences in clinical manifestations depending on the infection route and vaccination status, similar to findings from previous reports from the prairie dog–associated mpox outbreak in the United States (13). Therefore, prompt vaccination after exposure might prevent disease progression and should be considered for HCWs in environments requiring contact with monkeypox virus-infected patients; preexposure vaccination should also be considered. Second, precautions should be exercised when collecting specimens from patients with suspected mpox. For the safety of HCWs, instead of unroofing or aspirating the lesion with a sharp tool, the sample should be obtained by rubbing the surface of the lesion with a swab or collecting a scab with forceps (14). Because PCR is highly sensitive, a positive result can be obtained when samples are collected by using this method. Third, although tecovirimat is generally recommended for patients with severe mpox or high risk of dissemination (10), the drug was administered to our patient, who had localized infection, to prevent disease progression; prompt administration of tecovirimat might be necessary to maximize effectiveness. Most patients with mpox report extreme pain in the affected area. Thus, although the isolation period or the time until the virus is undetectable might not be shortened, antiviral treatment should be considered if skin lesions progress or pain is severe and no shortage of drugs exists.

In summary, we report a case of monkeypox virus infection in a HCW after a needlestick injury and a literature review of similar cases during the 2022 mpox outbreak. Although larger studies are needed to determine efficacy of postexposure vaccination prophylaxis, this case series indicates postexposure vaccination might have prevented dissemination of virus lesions. Therefore, clinicians should consider postexposure vaccination and tecovirimat or other antiviral drugs to inhibit local monkeypox virus spread and alleviate lesion pain.