Serological Evidence of Mpox Virus Infection During Peak Mpox Transmission in New York City, July to August 2022.

BACKGROUND: The extent to which infections may have been undetected in an epicenter of the 2022 mpox outbreak is unknown. METHODS: A serosurvey (July and August 2022) assessed the seroprevalence and correlates of mpox infection among a diverse sample of asymptomatic patients with no prior mpox diagnoses and no known histories of smallpox or mpox vaccination. We present seropositivity stratified by participant characteristics collected via survey. RESULTS: Two-thirds of 419 participants were cismen (281 of 419), of whom 59.1% (166 of 281) reported sex with men (MSM). The sample also included 109 ciswomen and 28 transgender/gender nonconforming/nonbinary individuals. Overall seroprevalence was 6.4% (95% confidence interval [CI], 4.1%-8.8%); 3.7% among ciswomen (95% CI, 1.0%-9.1%), 7.0% among cismen with only ciswomen partners (95% CI, 2.0%-11.9%), and 7.8% among MSM (95% CI, 3.7%-11.9%). There was little variation in seroprevalence by race/ethnicity, age group, HIV status, or number of recent sex partners. No participants who reported close contact with mpox cases were seropositive. Among participants without recent mpox-like symptoms, 6.3% were seropositive (95% CI, 3.6%-9.0%). CONCLUSIONS: Approximately 1 in 15 vaccine-naive people in our study had antibodies to mpox during the height of the NYC outbreak, indicating the presence of asymptomatic infections that could contribute to ongoing transmission.

Evidence of Mpox Virus Infection Among Persons Without Characteristic Lesions or Rash Presenting for First Dose of JYNNEOS Vaccine-District of Columbia, August 2022.

We assessed mpox virus prevalence in blood, pharyngeal, and rectal specimens among persons without characteristic rash presenting for JYNNEOS vaccine. Our data indicate that the utility of risk-based screening for mpox in persons without skin lesions or rash via pharyngeal swabs, rectal swabs, and/or blood is likely limited.

Prevalence of Undiagnosed Monkeypox Virus Infections during Global Mpox Outbreak, United States, June-September 2022.

Since May 2022, mpox has been identified in 108 countries without endemic disease; most cases have been in gay, bisexual, or other men who have sex with men. To determine number of missed cases, we conducted 2 studies during June-September 2022: a prospective serologic survey detecting orthopoxvirus antibodies among men who have sex with men in San Francisco, California, and a retrospective monkeypox virus PCR testing of swab specimens submitted for other infectious disease testing among all patients across the United States. The serosurvey of 225 participants (median age 34 years) detected 18 (8.0%) who were orthopoxvirus IgG positive and 3 (1.3%) who were also orthopoxvirus IgM positive. The retrospective PCR study of 1,196 patients (median age 30 years; 54.8% male) detected 67 (5.6%) specimens positive for monkeypox virus. There are likely few undiagnosed cases of mpox in regions where sexual healthcare is accessible and patient and clinician awareness about mpox is increased.

Possible Undetected Mpox Infection Among Persons Accessing Homeless Services and Staying in Encampments - San Francisco, California, October-November 2022.

Monkeypox (mpox) is a disease caused by an Orthopoxvirus. The 2022 multinational outbreak, which began in May 2022, has spread primarily by close skin-to-skin contact, including through sexual contact. Persons experiencing homelessness have been disproportionately affected by severe mpox (1). However, mpox prevalence and transmission pathways among persons experiencing homelessness are not known, and persons experiencing homelessness have not been specifically recommended to receive mpox vaccine during the 2022 outbreak (2,3). During October 25-November 3, 2022, a CDC field team conducted an orthopoxvirus seroprevalence survey among persons accessing homeless services or staying in encampments, shelters, or permanent supportive housing in San Francisco, California that had noted at least one case of mpox or served populations at risk. During field team visits to 16 unique sites, 209 participants completed a 15-minute survey and provided a blood specimen. Among 80 participants aged <50 years who did not report smallpox or mpox vaccination or previous mpox infection, two (2.5%) had detectable antiorthopoxvirus immunoglobulin (Ig) G antibody. Among 73 participants who did not report mpox vaccination or previous mpox infection and who were tested for IgM, one (1.4%) had detectable antiorthopoxvirus IgM. Together, these results suggest that three possible undetected mpox infections occurred among a sample of persons experiencing homelessness, highlighting the need to ensure that community outreach and prevention interventions, such as vaccination, are accessible to this population.

Minimally Invasive Blood Collection for an Mpox Serosurvey among People Experiencing Homelessness.

BACKGROUND: People experiencing homelessness (PEH) are underrepresented in public health and clinical research. Study methods that can improve participation by this group are needed. METHODS: In late 2022, the Centers for Disease Control and Prevention conducted an mpox serological survey using venipuncture among PEH in San Francisco, California. Blood collection by a minimally invasive device was offered if venipuncture was not possible or preferred. Participants who had a successful blood draw using the device were asked about device acceptability. RESULTS: Of the 209 successful blood collections, 137 (66%) were among participants who underwent venipuncture and 72 (34%) were among participants who used the device. Use of the device increased overall blood collection participation by 53%. Participants reported high acceptability and preference for the device over venipuncture. CONCLUSIONS: Minimally invasive blood collection devices may increase participation and representation of PEH in serosurveys.

Serologic responses to the MVA-based JYNNEOS mpox vaccine in a cohort of participants from the District of Columbia (D.C.).

We assessed early antibody responses after two doses of JYNNEOS (IMVANEX) mpox vaccine in the District of Columbia (D.C.) in persons at high risk for mpox without characteristic lesions or rash. Participants with PCR mpox negative specimens (oral swab, blood, and/or rectal swab) on the day of receipt of the first vaccine dose and who provided a baseline (day 0) serum sample and at least one serum sample at âˆ¼28, ∼42-56 days, or 180 days post vaccination were included in this analysis. Orthopoxvirus (OPXV)-specific IgG and IgM ELISAs and neutralizing antibody titers were performed, and longitudinal serologic responses were examined. Based on participants' IgG and IgM antibody levels at baseline, they were categorized as naïve or non-naïve. Linear mixed effects regression models were conducted to determine if IgG antibody response over time varied by age, sex, HIV status, and route of administration for both naïve and non-naïve participants. Among both naïve and non-naïve participants IgG seropositivity rates increased until day 42-56, with 89.4 % of naïve and 92.1 % of non-naïve participants having detectable IgG antibodies. The proportion of naive participants with detectable IgG antibodies declined by day 180 (67.7 %) but remained high among non-naïve participants (94.4 %). Neutralizing antibody titers displayed a similar pattern, increasing initially post vaccination but declining by day 180 among naïve participants. There were no significant serologic response differences by age, sex, or HIV status. Serologic response did vary by route of vaccine administration, with those receiving a combination of intradermal and subcutaneous doses displaying significantly higher IgG values than those receiving both doses intradermally. These analyses provide initial insights into the immunogenicity of a two-dose JYNNEOS PEP regimen in individuals at high risk of mpox exposure in the United States.

Serological responses to the MVA-based JYNNEOS monkeypox vaccine in a cohort of participants from the Democratic Republic of Congo.

The current worldwide monkepox outbreak has reaffirmed the continued threat monkeypox virus (MPXV) poses to public health. JYNNEOS, a Modified Vaccinia Ankara (MVA)-based live, non-replicating vaccine, was recently approved for monkeypox prevention for adults at high risk of MPXV infection in the United States. Although the safety and immunogenicity of JYNNEOS have been examined previously, the clinical cohorts studied largely derive from regions where MPXV does not typically circulate. In this study, we assess the quality and longevity of serological responses to two doses of JYNNEOS vaccine in a large cohort of healthcare workers from the Democratic Republic of Congo (DRC). We show that JYNNEOS elicits a strong orthopoxvirus (OPXV)-specific antibody response in participants that peaks around day 42, or 2 weeks after the second vaccine dose. Participants with no prior history of smallpox vaccination or exposure have lower baseline antibody levels, but experience a similar fold-rise in antibody titers by day 42 as those with a prior history of vaccination. Both previously naïve and vaccinated participants generate vaccinia virus and MPXV-neutralizing antibody in response to JYNNEOS vaccination. Finally, even though total OPXV-specific IgG titers and neutralizing antibody titers declined from their peak and returned close to baseline levels by the 2-year mark, most participants remain IgG seropositive at the 2-year timepoint. Taken together, our data demonstrates that JYNNEOS vaccination triggers potent OPXV neutralizing antibody responses in a cohort of healthcare workers in DRC, a monkeypox-endemic region. MPXV vaccination with JYNNEOS may help ameliorate the disease and economic burden associated with monkeypox and combat potential outbreaks in areas with active virus circulation.