An open-label, non-randomized study investigating the safety and efficacy of smallpox vaccine, LC16, as post-exposure prophylaxis for mpox.

Mpox is an acute exanthematous disease caused by the monkeypox virus. Since May 2022, it has spread as a community-acquired infection, mainly in Europe and the United States, and urgent measures to prevent this infection were also required in Japan. In this study, we investigated the post-exposure prophylaxis of mpox and safety after inoculating the smallpox vaccine. Participants in close contact with patients with mpox were inoculated with "Freeze-dried cell culture Smallpox Vaccine LC16," within 14 days after close contact. Six cases were registered, and all the participants were inoculated. No mpox symptoms or related complications were observed in the participants for 21 days after the close contact. Adverse events due to inoculation, such as rash, fever, lymphadenopathy, and local reaction at the inoculation site (comprising erythema, swelling, induration, and pain) were observed in the participants; however, all inoculation-related events were non-severe and non-serious, and the participants recovered during the 28-day observation period. The findings of this study suggest that inoculation with LC16 is an effective post-exposure prophylaxis in individuals who had close contact with patients with mpox. Further large-scale studies are warranted to validate these findings.

Efficacy and Safety of the Smallpox Vaccine for Postexposure Prophylaxis in Monkeypox: Protocol for an Open-Labeled, Single-Armed Study.

BACKGROUND: In May 2022, a case of monkeypox (currently known as "mpox") with no history of overseas travel was reported in the United Kingdom, followed by reports of infections reported in Europe, the United States, and other countries worldwide. Due to the significant overlap in immune responses among viruses of the genus Orthopoxvirus (including smallpox virus, mpox virus, and vaccinia virus), it is believed that cross-immunity can be achieved by administering the smallpox virus vaccine. In Japan, a smallpox vaccine (LC16m8 strain vaccine) has been approved; however, there was no regulatory approval for the mpox vaccine during the design of this study. Although it is believed that individuals exposed to the mpox virus may receive smallpox vaccination as mpox prophylaxis, the existing evidence is not clear. OBJECTIVE: The primary objective was to evaluate the efficacy of the LC16m8 strain vaccine, approved for smallpox in Japan, for postexposure prophylaxis against mpox when administered to close contacts of individuals with mpox. The secondary objective was to investigate the safety of the vaccine for postexposure prophylaxis against mpox. METHODS: The study aimed to enroll 100 vaccinated participants who had been identified as close contacts of individuals with mpox. Consent was obtained, and the participants are inoculated with the vaccine. Daily recordings of symptoms (body temperature, headache, rash, and side effects) were made until day 21 and then again on day 28. Furthermore, additional evaluations of adverse events were performed by the investigators on days 7, 14, 21, and 28. Considering that the maximum incubation period for mpox is 21 days, the primary end point is the presence or absence of the disease 21 days after close contact. The primary analysis focused on cases within 4 days of intense contact as it has been reported that vaccination within this timeframe can reduce the incidence of the disease. RESULTS: The first trial participant was enrolled on July 28, 2022, and the research period concluded in March 2023. The study results will be published in a peer-reviewed scientific journal. CONCLUSIONS: This study allowed us to investigate the efficacy and safety of the LC16m8 strain vaccine in postexposure prophylaxis against mpox. TRIAL REGISTRATION: Japan Registry of Clinical Trials jRCTs031220137; https://jrct.niph.go.jp/en-latest-detail/jRCTs031220137. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/46955.

Hemolysis Is Responsible for Elevation of Serum Iron Concentration After Regular Exercises in Judo Athletes.

Serum iron concentration increases in marathon athletes after running due to mechanical destruction of red blood cells (hemolysis). This study was performed to examine whether serum iron concentration increases after regular Judo exercise, and if so, whether such post-exercise iron increase is caused by hemolysis. We examined biochemical parameters related to red blood cell and iron metabolism in 16 male competitive Judo athletes before and after traditional exercise training composed of basic movements and freestyle matchup. The parameters were adjusted for changes in plasma volume based on simultaneously measured albumin concentration. The red blood cell count, hemoglobin concentration, and hematocrit levels decreased significantly, by 6.0-8.4%, after Judo exercise. The serum iron concentration and transferrin saturation increased significantly, from 87 ± 34 µg/dL to 98 ± 29 µg/dL and from 27.1 ± 9.7% to 31.2 ± 9.0%, respectively. Furthermore, the serum free hemoglobin level increased by 33.9% (p < 0.05), and haptoglobin concentration decreased by 19.2% (p < 0.001). A significant negative correlation was observed between Δ haptoglobin concentration and Δ serum iron concentration (r = - 0.551, p = 0.027). The results of this study indicate that serum iron concentration increases significantly after Judo exercise due to hemolysis.