Vaccinia-Virus-Based Vaccines Are Expected to Elicit Highly Cross-Reactive Immunity to the 2022 Monkeypox Virus

Polyvalent mpox mRNA vaccines elicit robust immune responses and confer potent protection against vaccinia virus

The 2022 mpox outbreak led the World Health Organization (WHO) to declare it a public health emergency of international concern (PHEIC). There is a need to develop more effective and safer mpox virus (MPXV)-specific vaccines in response to the mpox epidemic. The mRNA vaccine is a promising platform to protect against MPXV infection. In this study, we construct two bivalent MPXV mRNA vaccines, designated LBA (B6R-A29L) and LAM (A35R-M1R), and a quadrivalent mRNA vaccine, LBAAM (B6R-A35R-A29L-M1R). The immunogenicity and protective efficacy of these vaccines alone or in combination were evaluated in a lethal mouse model. All mRNA vaccine candidates could elicit potential antigen-specific humoral and cellular immune responses and provide protection against vaccinia virus (VACV) infection. The protective effect of the combination of two bivalent mRNA vaccines and the quadrivalent vaccine was superior to that of the individual bivalent mRNA vaccine. Our study provides valuable insights for the development of more efficient and safer mRNA vaccines against mpox.

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 ∼28, ∼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.

Paediatric, maternal, and congenital mpox: a systematic review and meta-analysis

BACKGROUND

Although mpox has been detected in paediatric populations in central and west Africa for decades, evidence synthesis on paediatric, maternal, and congenital mpox, and the use of vaccines and therapeutics in these groups, is lacking. A systematic review is therefore indicated to set the research agenda.

METHODS

We conducted a systematic review and meta-analysis, searching articles in Embase, Global Health, MEDLINE, CINAHL, Web of Science, Scopus, SciELO, and WHO databases from inception to April 17, 2023. We included studies reporting primary data on at least one case of confirmed, suspected, or probable paediatric, maternal, or congenital mpox in humans or the use of third-generation smallpox or mpox vaccines, targeted antivirals, or immune therapies in at least one case in our population of interest. We included clinical trials and observational studies in humans and excluded reviews, commentaries, and grey literature. A pooled estimate of the paediatric case fatality ratio was obtained using random-effects meta-analysis. This study is registered with PROSPERO (CRD420223336648).

FINDINGS

Of the 61 studies, 53 reported paediatric outcomes (n=2123 cases), seven reported maternal or congenital outcomes (n=32 cases), two reported vaccine safety (n=28 recipients), and three reported transmission during breastfeeding (n=4 cases). While a subset of seven observational studies (21 children and 12 pregnant individuals) reported uneventful treatment with tecovirimat, there were no randomised trials reporting safety or efficacy for any therapeutic agent. Among children, the commonest clinical features included rash (86 [100%] of 86), fever (63 [73%] of 86), and lymphadenopathy (40 [47%] of 86). Among pregnant individuals, rash was reported in 23 (100%) of 23; fever and lymphadenopathy were less common (six [26%] and three [13%] of 23, respectively). Most paediatric complications (12 [60%] of 20) arose from secondary bacterial infections. The pooled paediatric case fatality ratio was 11% (95% CI 4-20), I2=75%. Data from 12 pregnancies showed half resulted in fetal death. Research on vaccine and immune globulin safety remains scarce for children and absent for pregnant individuals.

INTERPRETATION

Our review highlights critical knowledge gaps in the epidemiology, prevention, and treatment of mpox in children and pregnant individuals, especially those residing in endemic countries. Increased funding, international collaboration, and equitable research is needed to inform mpox control strategies tailored for at-risk communities in endemic countries.

FUNDING

None.

TRANSLATIONS

For the French, Spanish and Portuguese translations of the abstract see Supplementary Materials section.

Cross-Reactivity Assessment of Vaccine-Derived SARS-CoV-2 T Cell Responses against BA.2.86 and JN.1

The SARS-CoV-2 Omicron sub-variants BA.2.86 and JN.1 contain multiple mutations in the spike protein that were not present in previous variants of concern and Omicron sub-variants. Preliminary research suggests that these variants reduce the neutralizing capability of antibodies induced by vaccines, which is particularly significant for JN.1. This raises concern as many widely deployed COVID-19 vaccines are based on the spike protein of the ancestral Wuhan strain of SARS-CoV-2. While T cell responses have been shown to be robust against previous SARS-CoV-2 variants, less is known about the impact of mutations in BA.2.86 and JN.1 on T cell responses. We evaluate the effect of mutations specific to BA.2.86 and JN.1 on experimentally determined T cell epitopes derived from the spike protein of the ancestral Wuhan strain and the spike protein of the XBB.1.5 strain that has been recommended as a booster vaccine. Our data suggest that BA.2.86 and JN.1 affect numerous T cell epitopes in spike compared to previous variants; however, the widespread loss of T cell recognition against these variants is unlikely.

Mpox Neutralizing Antibody Response to LC16m8 Vaccine in Healthy Adults

BACKGROUND: Vaccination against mpox (formerly known as monkeypox), an infectious disease caused by the monkeypox virus (MPXV), is needed to prevent outbreaks and consequent public health concerns. The LC16m8 vaccine, a dried cell-cultured proliferative live attenuated vaccinia virus–based vaccine, was approved in Japan against smallpox and mpox. However, its immunogenicity and efficacy against MPXV have not been fully assessed. We assessed the safety and immunogenicity of LC16m8 against MPXV in healthy adults. METHODS: We conducted a single-arm study that included 50 participants who were followed up for 168 days postvaccination. The primary end point was the neutralizing antibody seroconversion rate against MPXVs, including the Zr599 and Liberia strains, on day 28. The secondary end points included the vaccine “take” (major cutaneous reaction) rate, neutralizing titer kinetics against MPXV and vaccinia virus (LC16m8) strains, and safety outcomes. RESULTS: Seroconversion rates on day 28 were 72% (36 of 50), 70% (35 of 50), and 88% (44 of 50) against the Zr599 strain, the Liberia strain, and LC16m8, respectively. On day 168, seroconversion rates decreased to 30% (15 of 50) against the Zr599 and Liberia strains and to 76% (38 of 50) against LC16m8. The vaccine “take” (broad definition) rate on day 14 was 94% (46 of 49). Adverse events (AEs), including common solicited cutaneous reactions, occurred in 98% (45 of 48) of participants; grade 3 severity AEs occurred in 16% (8 of 50). No deaths, serious AEs, or mpox onset incidences were observed up to day 168. CONCLUSIONS: The LC16m8 vaccine generated neutralizing antibody responses against MPXV in healthy adults. No serious safety concerns occurred with LC16m8 use. (Funded by the Ministry of Health, Labour and Welfare of Japan; Japan Registry of Clinical Trials number, jRCTs031220171.)

Synthetic modified vaccinia Ankara vaccines confer cross-reactive and protective immunity against mpox virus

BACKGROUND

Although the mpox global health emergency caused by mpox virus (MPXV) clade IIb.1 has ended, mpox cases are still reported due to low vaccination coverage and waning immunity. COH04S1 is a clinically evaluated, multiantigen COVID-19 vaccine candidate built on a fully synthetic platform of the highly attenuated modified vaccinia Ankara (MVA) vector, representing the only FDA-approved smallpox/mpox vaccine JYNNEOS. Given the potential threat of MPXV resurgence and need for vaccine alternatives, we aimed to assess the capacity COH04S1 and its synthetic MVA (sMVA) backbone to confer MPXV-specific immunity.

METHODS

We evaluated orthopoxvirus-specific and MPXV cross-reactive immune responses in samples collected during a Phase 1 clinical trial of COH04S1 and in non-human primates (NHP) vaccinated with COH04S1 or its sMVA backbone. MPXV cross-reactive immune responses in COH04S1-vaccinated healthy adults were compared to responses measured in healthy subjects vaccinated with JYNNEOS. Additionally, we evaluated the protective efficacy of COH04S1 and sMVA against mpox in mpox-susceptible CAST/EiJ mice.

RESULTS

COH04S1-vaccinated individuals develop robust orthopoxvirus-specific humoral and cellular responses, including cross-reactive antibodies to MPXV-specific virion proteins as well as MPXV cross-neutralizing antibodies in 45% of the subjects. In addition, NHP vaccinated with COH04S1 or sMVA show similar MPXV cross-reactive antibody responses. Moreover, MPXV cross-reactive humoral responses elicited by COH04S1 are comparable to those measured in JYNNEOS-vaccinated subjects. Finally, we show that mice vaccinated with COH04S1 or sMVA are protected from lung infection following challenge with MPXV clade IIb.1.

CONCLUSIONS

These results demonstrate the capacity of sMVA vaccines to elicit cross-reactive and protective orthopox-specific immunity against MPXV, suggesting that COH04S1 and sMVA could be developed as bivalent or monovalent mpox vaccine alternatives against MPXV.

Human mpox: global trends, molecular epidemiology and options for vaccination

The eradication of smallpox and the cessation of vaccination have led to the growth of the susceptible human population to poxviruses. This has led to the increasing detection of zoonotic orthopoxviruses. Among those viruses, monkeypox virus (MPV) is the most commonly detected in Western and Central African regions. Since 2022, MPV is causing local transmission in newly affected countries all over the world. While the virus causing the current outbreak remains part of clade II (historically referred to as West African clade), it has a significant number of mutations as compared to other clade II sequences and is therefore referred to as clade IIb. It remains unclear whether those mutations may have caused a change in the virus phenotype. Vaccine effectiveness data show evidence of a high cross-protection of vaccines designed to prevent smallpox against mpox. These vaccines therefore represent a great opportunity to control human-to-human transmission, provided that their availability has short time-frames and that mistakes from the recent past (vaccine inequity) will not be reiterated.

Mpox in people living with HIV

PURPOSE OF REVIEW

The 2022 global outbreak of mpox disproportionally affected people with HIV (PWH). We review the data on the presentation, treatment, and prevention of mpox in PWH.

RECENT FINDINGS

Most PWH with mpox had a mild and self-limiting illness, no different to people without HIV. A higher rate of rectal symptoms has been reported among PWH and those with advanced HIV disease were at higher risk of severe disease, hospitalization, and death. Treatment with antivirals was widely used in hospitalized patients without any randomized control trial data to support its use and without any data specifically in PWH. Use of smallpox vaccines to prevent mpox is safe in PWH regardless of CD4+ cell count. There is limited data on efficacy in those with lower CD4+ cell count and on long-term protective efficacy.

SUMMARY

PWH should be offered vaccination against mpox in line with national guidelines. PWH should be individually risk-assessed for severe mpox, based on their CD4+ cell count and co-morbidities and ideally recruited into treatment trials to build an evidence base on efficacy. HIV and other sexually transmitted infection testing should be offered to all people diagnosed with mpox.

Characterizing the acute antibody response of monkeypox and MVA-BN vaccine following an Australian outbreak

In response to the emergence of the monkeypox virus (MPXV) in Australia in May 2022, we developed and evaluated indirect immunofluorescence assays (IFA) for MPXV and Vaccinia virus (VACV) IgG and IgM antibodies using serum samples from patients with nucleic acid amplification test (NAAT)-confirmed mpox and uninfected unvaccinated controls. Additionally, 47 healthcare workers receiving two doses of the third-generation smallpox vaccine Modified Vaccinia Ankara-Bavarian Nordic (MVA-BN) undertook serial serum collection to describe the serological response to vaccination. MPXV antibodies were detected in 16/18 individuals with NAAT-confirmed mpox (sensitivity 0.89, specificity 1.00), and VACV antibodies were detected in 28/29 individuals who received two doses of MVA-BN vaccine (sensitivity 0.97, specificity 1.00). Detectable antibody in subjects historically vaccinated with early-generation vaccines against smallpox was found in 7/7 subjects, at a median of 48 years following vaccination. MPXV NAAT-positive patients with serum samples collected within the first 14 days after rash onset had detectable IgG and IgM in 9/12 and 5/12 of patients, respectively, with maintenance of IgG and disappearance of IgM titers after 60 days. While specificity was high when testing unvaccinated and uninfected subjects, significant cross-reactivity between MPXV and VACV antibodies was observed.

Screening, Expression and Identification of Nanobody Against Monkeypox Virus A35R

Introduction

The monkeypox (Mpox) virus epidemic presents a significant risk to global public health security. A35R, a crucial constituent of EEV, plays a pivotal role in virus transmission, serves as a vital target for vaccine development, and has potential for serological detection. Currently, there is a dearth of research on nanobodies targeting A35R. The purpose of this study is to identify specific nanobodies target A35R, so as to provide new antibody candidates for Mpox vaccine development and diagnostic kit development.

Methods

Three nanobodies specific to the monkeypox virus protein A35R were screened from a naïve phage display library. After four rounds of panning, positive phage clones were identified by enzyme-linked immunosorbent assay (ELISA). Further, the nanobody fusion protein was constructed in pNFCG1-IgG1-Fc vector and expressed in HEK293F cells and purified by affinity chromatography. The specificity and affinity of the nanobodies were identified by ELISA. The binding kinetics of the VHH antibody to A35R were assessed via employment of a bio-layer interferometry (BLI) apparatus, thereby determining the nanobodies affinity.

Results

The three purified nanobodies showed specific high-affinity binding MPXV A35R, of them, VHH-1 had the best antigen binding affinity (EC50 = 0.010 ug/mL). In addition, VHH-1 on Protein A biosensor can bind Mpox virus A35R, with an affinity constant of 54 nM as determined in BLI assay.

Conclusion

In sum, we has obtained three nanobody strains against Mpox virus A35R with significant affinity and specificity, therefore laying an essential foundation for further research as well as the applications of diagnostic and therapeutic tools of Mpox virus.

Comprehensive overview of 2022 human monkeypox outbreak and its pathology, prevention, and treatment: A strategy for disease control

The 2022 Monkeypox virus, an evolved DNA strain originating in Africa, exhibits heightened human-to-human transmissibility and potential animal transmission. Its host remains unidentified. While its initial slow transmission rate restrained global impact, 2022 saw a surge in cases, causing widespread concern in over 103 countries by September. This virus's distinctive human-to-human transmission marks a crucial shift, demanding a prompt revaluation of containment strategies. However, the host source for this shift requires urgent research attention. Regrettably, no universal preventive or curative methods have emerged for this evolved virus. Repurposed from smallpox vaccines, only some vaccinations offer a partial defense. Solely one therapeutic drug is available. The article's essence is to provide a comprehensive grasp of the virus's epidemiology, morphology, immune invasion mechanisms, and existing preventive and treatment measures. This knowledge equips researchers to devise strategies against its spread and potential public health implications.

Mpox vaccine and infection-driven human immune signatures: an immunological analysis of an observational study

BACKGROUND

Monkeypox virus has recently infected more than 88 000 people, raising concerns about our preparedness against this emerging viral pathogen. Licensed and approved for mpox, the JYNNEOS vaccine has fewer side-effects than previous smallpox vaccines and has shown immunogenicity against monkeypox in animal models. This study aims to elucidate human immune responses to JYNNEOS vaccination compared with mpox-induced immunity.

METHODS

Peripheral blood mononuclear cells and sera were obtained from ten individuals vaccinated with one or two doses of JYNNEOS and six individuals diagnosed with monkeypox virus infection. Samples were obtained from seven individuals before vaccination to serve as a baseline. We examined the polyclonal serum (ELISA) and single B-cell (heavy chain gene and transcriptome data) antibody repertoires and T-cell responses (activation-induced marker and intracellular cytokine staining assays) induced by the JYNNEOS vaccine versus monkeypox virus infection.

FINDINGS

All participants were men between the ages of 21 and 60 years, except for one woman in the group of mpox-convalescent individuals, and none had previous orthopoxvirus exposure. All mpox cases were mild. Vaccinee samples were collected 6-33 days after the first dose and 5-40 days after the second dose. Mpox-convalescent samples were collected 20-102 days after infection. In vaccine recipients, gene-level plasmablast and antibody responses were negligible and sera displayed moderate binding to recombinant orthopoxviral proteins (A29L, A35R, E8L, A30L, A27L, A33R, B18R, and L1R) and native proteins from the 2022 monkeypox outbreak strain. By contrast, recent monkeypox virus infection (within 20-102 days) induced robust serum antibody responses to monkeypox virus proteins and to native monkeypox virus proteins from a viral isolate obtained during the 2022 outbreak. JYNNEOS vaccine recipients presented robust orthopoxviral CD4+ and CD8+ T-cell responses.

INTERPRETATION

Infection with monkeypox virus resulted in robust B-cell and T-cell responses, whereas immunisation with JYNNEOS elicited more robust T-cell responses. These data can help to inform vaccine design and policies for preventing mpox in humans.

FUNDING

National Cancer Institute (National Institutes of Health), National Institute of Allergy and Infectious Diseases (National Institutes of Health), and Icahn School of Medicine.

Examination of the cross-reactivity between vaccinia virus Tiantan strain and monkeypox virus

AIM

To investigate the cross-reactivity between the sera collected from Vaccinia Virus Tiantan Strain vaccinated rabbits and viral antigens of monkeypox virus.

METHODS

Vaccinia viruses were prepared on chicken embryo fibroblasts (CEF) and Vero cells respectively named as CEF-VTT NVSI-1 and Vero-VTT NVSI-1. Rabbits were inoculated with a total of three doses of adjuvanted 1.3 × 108 PFU CEF-VTT NVSI-1 each dose or adjuvanted 3.9 × 107 PFU Vero-VTT NVSI-1 (Freunds complete adjuvant) via the subcutaneous route. We then performed the enzyme-linked immunosorbent assay (ELISA) and bio-layer interferometry (BLI) for determination of the binding activity and affinity of immune sera to five crucial surface antigens on monkeypox virus including A35, B6R, H3 and to corresponding homologous antigens A33R, B5 and L1R of vaccinia virus. For comparison, plaque reduction neutralizing tests were used to evaluate the neutralization of immune sera against vaccinia virus.

RESULTS

Both CEF-VTT NVSI-1 and Vero-VTT NVSI-1 vaccinations following planned schedule could induce neutralizing antibody titers greater than 1:2048 in rabbit sera. Binding antibodies targeting monkeypox viral antigens were confirmed by both indirect ELISA and BLI methods. Indirect ELISA for rabbit sera revealed 1:51200 binding antibody titers to A35/B6R/H3 monkeypox virus antigens while BLI tests yielded affinities at 2 × 10-6 to 8 × 10-7 between the sera and the three antigens. Similarly, such sera showed binding strength to vaccinia virus antigens A33R/B5/L1R consistent with that to three preceding monkeypox virus antigens. These results demonstrated the cross-reactivity between the sera of vaccinia virus vaccinated animals and monkeypox virus antigens. Traditional ELISA test and BLI method displayed a high consistency in antigen screening and they were further proved to correlate to the results of plaque reduction neutralizing test, which indicates that BLI could be utilized as an indirect alternative for assessment of neutralizing activity of samples in response to live virus.

CONCLUSIONS

Sera of vaccinia virus-vaccinated rabbits exhibited cross-reactivity with viral antigens of monkeypox virus. Potential in improving the accuracy of antigen discovery while reducing the lengthy work needed for the screening as BLI method possesses, it contributes greatly to the rapid preliminary evaluation of immune response generated by vaccines.

Generation of recombinant mAbs to vaccinia virus displaying high affinity and potent neutralization

Members of the Orthopoxvirus genus can cause severe infections in humans. Global vaccination against smallpox, caused by the variola virus, resulted in the eradication of the disease in 1980. Shortly thereafter, vaccination was discontinued, and as a result, a large proportion of the current population is not protected against orthopoxviruses. The concerns that the variola virus or other engineered forms of poxviruses may re-emerge as bioweapons and the sporadic outbreaks of zoonotic members of the family, such as Mpox, which are becoming more frequent and prevalent, also emphasize the need for an effective treatment against orthopoxviruses. To date, the most effective way to prevent or control an orthopoxvirus outbreak is through vaccination. However, the traditional vaccinia-based vaccine may cause severe side effects. Vaccinia immune globulin was approved by the U.S. Food and Drug Administration (FDA) for the treatment of vaccine adverse reactions and was also used occasionally for the treatment of severe orthopoxvirus infections. However, this treatment carries many disadvantages and is also in short supply. Thus, a recombinant alternative is highly needed. In this study, two non-human primates were immunized with live vaccinia virus, producing a robust and diverse antibody response. A phage-display library was constructed based on the animal's lymphatic organs, and a panel of neutralizing monoclonal antibodies (mAbs), recognizing diverse proteins of the vaccinia virus, was selected and characterized. These antibodies recognized both mature virion and enveloped virion forms of the virus and exhibited high affinity and potent in vitro neutralization capabilities. Furthermore, these monoclonal antibodies were able to neutralize Mpox 2018 and 2022 strains, suggesting a potential for cross-species protection. We suggest that a combination of these mAbs has the potential to serve as recombinant therapy both for vaccinia vaccine adverse reactions and for orthopoxvirus infections. IMPORTANCE In this manuscript, we report the isolation and characterization of several recombinant neutralizing monoclonal antibodies (mAbs) identified by screening a phage-display library constructed from lymphatic cells collected from immunized non-human primates. The antibodies target several different antigens of the vaccinia virus, covering both mature virion and extracellular enveloped virion forms of the virus. We document strong evidence indicating that they exhibit excellent affinity to their respective antigens and, most importantly, optimal in vitro neutralization of the virus, which exceeded that of vaccinia immune globulin. Furthermore, we present the ability of these novel isolated mAbs (as well as the sera collected from vaccinia-immunized animals) to neutralize two Mpox strains from the 2018 to 2022 outbreaks. We believe that these antibodies have the potential to be used for the treatment of vaccinia vaccine adverse reactions, for other orthopoxvirus infections, and in cases of unexpected bioterror scenarios.

HMMPolish: a coding region polishing tool for TGS-sequenced RNA viruses

Access to accurate viral genomes is important to downstream data analysis. Third-generation sequencing (TGS) has recently become a popular platform for virus sequencing because of its long read length. However, its per-base error rate, which is higher than next-generation sequencing, can lead to genomes with errors. Polishing tools are thus needed to correct errors either before or after sequence assembly. Despite promising results of available polishing tools, there is still room to improve the error correction performance to perform more accurate genome assembly. The errors, particularly those in coding regions, can hamper analysis such as linage identification and variant monitoring. In this work, we developed a novel pipeline, HMMPolish, for correcting (polishing) errors in protein-coding regions of known RNA viruses. This tool can be applied to either raw TGS reads or the assembled sequences of the target virus. By utilizing profile Hidden Markov Models of protein families/domains in known viruses, HMMPolish can correct errors that are ignored by available polishers. We extensively validated HMMPolish on 34 datasets that covered four clinically important viruses, including HIV-1, influenza-A, norovirus, and severe acute respiratory syndrome coronavirus 2. These datasets contain reads with different properties, such as sequencing depth and platforms (PacBio or Nanopore). The benchmark results against popular/representative polishers show that HMMPolish competes favorably on error correction in coding regions of known RNA viruses.

Current Status of Epidemiology, Diagnosis, Therapeutics, and Vaccines for the Re-Emerging Human Monkeypox Virus

Monkeypox (Mpox) virus, a member of the Poxviridae family, causes a severe illness similar to smallpox, which is characterized by symptoms such as high fever, rash, and pustules. Human-to-human transmission cases have been reported but remained low since the first recorded case of human infection occurred in the Congo in 1970. Recently, Mpox has re-emerged, leading to an alarming surge in infections worldwide since 2022, originating in the United Kingdom. Consequently, the World Health Organization (WHO) officially declared the '2022-23 Mpox outbreak'. Currently, no specific therapy or vaccine is available for Mpox. Therefore, patients infected with Mpox are treated using conventional therapies developed for smallpox. However, the vaccines developed for smallpox have demonstrated only partial efficacy against Mpox, allowing viral transmission among humans. In this review, we discuss the current epidemiology of the ongoing Mpox outbreak and provide an update on the progress made in diagnosis, treatment, and development of vaccines for Mpox.

Monkeypox Virus: A Comprehensive Overview of Viral Pathology, Immune Response, and Antiviral Strategies

BACKGROUND

The years 2022-2023 witnessed a monkeypox virus (mpox) outbreak in some countries worldwide, where it exists in an endemic form. However, the number of infectious cases is continuously on the rise, and there has been an unexpected, drastic increase in cases that result from sustained transmission in non-endemic regions of the world. Under this scenario, it is pertinent for the world to be aware of healthcare threats to mpox infection. This review aimed to compile advanced data regarding the different aspects of mpox disease.

METHODS

A comprehensive strategy for the compilation of recent data was adopted to add data regarding mpox, biology, viral pathology, immune response, and brief details on the antiviral strategies under trial; the search was limited to 2016-2023. The aim is to make the scientific community aware of diverse aspects of mpox.

RESULTS

Consequently, detailed insights have been drawn with regard to the nature, epidemiology, etiology, and biological nature of mpox. Additionally, its host interaction and viral infectious cycle and immune interventions have been briefly elaborated. This comprehensively drawn literature review delivers brief insights into the biological nature, immune responses, and clinical developments in the form of therapeutics against mpox. This study will help scientists understand the biological nature and responses in hosts, which will further help clinicians with therapeutic handling, diagnosis, and treatment options.

CONCLUSIONS

This study will provide updated information on mpox's pathology, immune responses, and antiviral strategies. Moreover, it will also help the public to become educated on the healthcare-associated threat and take timely mitigation measures against expected mpox outbreaks in the future.

Intra- and interhost genomic diversity of monkeypox virus

The impact and frequency of infectious disease outbreaks demonstrate the need for timely genomic surveillance to inform public health responses. In the largest known outbreak of mpox, genomic surveillance efforts have primarily focused on high-incidence nations in Europe and the Americas, with a paucity of data from South-East Asia and the Western Pacific. Here we analyzed 102 monkeypox virus (MPXV) genomes sampled from 56 individuals in Melbourne, Australia. All genomes fell within the 2022 MPXV outbreak lineage (B.1), with likely onward local transmission detected. We observed within-host diversity and instances of co-infection, and highlight further examples of structural variation and apolipoprotein B editing complex-driven micro-evolution in the current MPXV outbreak. Updating our understanding of MPXV emergence and diversification will inform public health measures and enable monitoring of the virus' evolutionary trajectory throughout the mpox outbreak.

Targeting the MR1-MAIT cell axis improves vaccine efficacy and affords protection against viral pathogens

Mucosa-associated invariant T (MAIT) cells are MR1-restricted, innate-like T lymphocytes with tremendous antibacterial and immunomodulatory functions. Additionally, MAIT cells sense and respond to viral infections in an MR1-independent fashion. However, whether they can be directly targeted in immunization strategies against viral pathogens is unclear. We addressed this question in multiple wild-type and genetically altered but clinically relevant mouse strains using several vaccine platforms against influenza viruses, poxviruses and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We demonstrate that 5-(2-oxopropylideneamino)-6-D-ribitylaminouracil (5-OP-RU), a riboflavin-based MR1 ligand of bacterial origin, can synergize with viral vaccines to expand MAIT cells in multiple tissues, reprogram them towards a pro-inflammatory MAIT1 phenotype, license them to bolster virus-specific CD8+ T cell responses, and potentiate heterosubtypic anti-influenza protection. Repeated 5-OP-RU administration did not render MAIT cells anergic, thus allowing for its inclusion in prime-boost immunization protocols. Mechanistically, tissue MAIT cell accumulation was due to their robust proliferation, as opposed to altered migratory behavior, and required viral vaccine replication competency and Toll-like receptor 3 and type I interferon receptor signaling. The observed phenomenon was reproducible in female and male mice, and in both young and old animals. It could also be recapitulated in a human cell culture system in which peripheral blood mononuclear cells were exposed to replicating virions and 5-OP-RU. In conclusion, although viruses and virus-based vaccines are devoid of the riboflavin biosynthesis machinery that supplies MR1 ligands, targeting MR1 enhances the efficacy of vaccine-elicited antiviral immunity. We propose 5-OP-RU as a non-classic but potent and versatile vaccine adjuvant against respiratory viruses.

Evaluation of Monkeypox- and Vaccinia virus-neutralizing antibodies in human serum samples after vaccination and natural infection

Introduction

In early to mid-2022, an unexpected outbreak of Monkeypox virus infections occurred outside the African endemic regions. Vaccines originally developed in the past to protect against smallpox are one of the available countermeasures to prevent and protect against Orthopoxvirus infections. To date, there are few studies on the cross-reactivity of neutralizing antibodies elicited by previous vaccinia virus-based vaccination and/or Monkeypox virus infection. The aim of this study was to evaluate a possible approach to performing Monkeypox and vaccinia live-virus microneutralization assays in which the read-out is based on the production of cytopathic effect in the cell monolayer.

Methods

Given the complexity of Orthopoxviruses, the microneutralization assay was performed in such a way as to uncover a potential role of complement, with and without the addition of an external source of Baby Rabbit Complement. A set of human serum samples from individuals who had been naturally infected with Monkeypox virus and individuals who may have and not have undergone vaccinia virus vaccinations, was used to evaluate the performance, sensitivity, and specificity of the assay.

Results and conclusions

The results of the present study confirm the presence and cross-reactivity of antibodies elicited by vaccinia-based vaccines, which proved able to neutralize the Monkeypox virus in the presence of an external source of complement.

Highly attenuated poxvirus-based vaccines against emerging viral diseases

Although one member of the poxvirus family, variola virus, has caused one of the most devastating human infections worldwide, smallpox, the knowledge gained over the last 30 years on the molecular, virological and immunological mechanisms of these viruses has allowed the use of members of this family as vectors for the generation of recombinant vaccines against numerous pathogens. In this review, we cover different aspects of the history and biology of poxviruses with emphasis on their application as vaccines, from first- to fourth-generation, against smallpox, monkeypox, emerging viral diseases highlighted by the World Health Organization (COVID-19, Crimean-Congo haemorrhagic fever, Ebola and Marburg virus diseases, Lassa fever, Middle East respiratory syndrome and severe acute respiratory syndrome, Nipah and other henipaviral diseases, Rift Valley fever and Zika), as well as against one of the most concerning prevalent virus, the Human Immunodeficiency Virus, the causative agent of AcquiredImmunodeficiency Syndrome. We discuss the implications in human health of the 2022 monkeypox epidemic affecting many countries, and the rapid prophylactic and therapeutic measures adopted to control virus dissemination within the human population. We also describe the preclinical and clinical evaluation of the Modified Vaccinia virus Ankara and New York vaccinia virus poxviral strains expressing heterologous antigens from the viral diseases listed above. Finally, we report different approaches to improve the immunogenicity and efficacy of poxvirus-based vaccine candidates, such as deletion of immunomodulatory genes, insertion of host-range genes and enhanced transcription of foreign genes through modified viral promoters. Some future prospects are also highlighted.

Poc (Pox), a term for various infectious diseases in the history of public health and epidemiology: the dreaded Smallpox, the almost unknown Alastrim and the Mpox

Introduction

In 2022, the appearance of cases of Mpox outside the countries where the disease is endemic, and of some cases of human-to-human transmission, alerted the scientific community to a virus that is closely related to the smallpox virus. Mpox is a zoonosis and can be transmitted to humans. Following the eradication of smallpox in 1980 and the subsequent cessation of smallpox vaccination, it is emerging as the most important Orthopoxvirus in terms of public health impact.

Methods

In outlining the current situation of Mpox in the world, the authors frame the virus responsible within a broader reflection on the Orthopoxvirus family, focusing particular attention on the Variola virus, which formerly caused millions of deaths.

Discussion

Since Edward Jenner initiated the practice of vaccination, a progressive and careful vaccination campaign has led to the eradication not only of human smallpox but also of a minor form, called Alastrim, which was caused by the same virus. The mode of transmission of Mpox has been debated. At first, it seemed that the disease mainly, though not exclusively, affected men who had sex with other men. This conviction has been partially revised and the WHO recently changed the name of the disease from Monkeypox to Mpox, thereby alleviating the stigma involved.

Conclusion

The recent human cases of Mpox have prompted greater surveillance and research into the biology of MPXV and other closely related poxviruses. Studies have focused on the natural history of the virus, its transmission, pathogenesis, host interactions and evolution, and on the development of drugs and vaccines to prevent its spread.

Unexpectedly higher levels of anti-orthopoxvirus neutralizing antibodies are observed among gay men than general adult population

BACKGROUND

The confirmed cases in the current outbreak of Monkeypox are predominantly identified in the networks of men who have sex with men (MSM). The preexisting antibodies may profoundly impact the transmission of monkeypox virus (MPXV), however the current-day prevalence of antibodies against MPXV among gay men is not well characterized.

METHODS

A cohort of gay men (n = 326) and a cohort of the general adult population (n = 295) were enrolled in this study. Binding antibodies responses against MPXV/vaccinia and neutralizing antibody responses against vaccinia virus (Tiantan strain) were measured. The antibody responses of these two cohorts were then compared, as well as the responses of individuals born before and in/after 1981 (when the smallpox vaccination ceased in China). Finally, the correlation between the anti-MPXV antibody responses and the anti-vaccinia antibody responses, and the associations between preexisting anti-orthopoxvirus antibody responses and the diagnosed sexually transmitted infections (STIs) in the MSM cohort were analyzed separately.

RESULTS

Our data showed that binding antibodies against MPXV H3, A29, A35, E8, B6, M1 proteins and vaccinia whole-virus lysate could be detected in individuals born both before and in/after 1981, of which the prevalence of anti-vaccinia binding antibodies was significantly higher among individuals born before 1981 in the general population cohort. Moreover, we unexpectedly found that the positive rates of binding antibody responses against MPXV H3, A29, A35, E8 and M1 proteins were significantly lower among individuals of the MSM cohort born in/after 1981, but the positive rates of anti-MPXV B6 and anti-vaccinia neutralizing antibody responses were significantly higher among these individuals compared to those of age-matched participants in the general population cohort. Additionally, we demonstrated that the positive and negative rates of anti-MPXV antibody responses were associated with the anti-vaccinia antibody responses among individuals born before 1981 in the general population cohort, but no significant association was observed among individuals born in/after 1981 in both cohorts. The positive rates of both the binding and the neutralizing antibody responses were comparable between individuals with and without diagnosed STIs in the MSM cohort.

CONCLUSIONS

Anti-MPXV and anti-vaccinia antibodies could be readily detected in an MSM cohort and a general population cohort. And a higher level of anti-vaccinia neutralizing antibody responses was observed among individuals who did not get vaccinated against smallpox in the MSM cohort compared to age-matched individuals in the general population cohort.

Progress and prospects on vaccine development against Monkeypox Infection

The monkeypox virus (MPOX) is an uncommon zoonotic illness brought on by an orthopoxvirus (OPXV). MPOX can occur with symptoms similar to smallpox. Since April 25, 2023, 110 nations have reported 87,113 confirmed cases and 111 fatalities. Moreover, the outspread prevalence of MPOX in Africa and a current outbreak of MPOX in the U.S. have made it clear that naturally occurring zoonotic OPXV infections remain a public health concern. Existing vaccines, though they provide cross-protection to MPOX, are not specific for the causative virus, and their effectiveness in the light of the current multi-country outbreak is still to be verified. Furthermore, as a sequel of the eradication and cessation of smallpox vaccination for four decades, MPOX found a possibility to re-emerge, but with distinct characteristics. The World Health Organization (WHO) suggested that nations use affordable MPOX vaccines within a framework of coordinated clinical effectiveness and safety evaluations. Vaccines administered in the smallpox control program and conferred immunity against MPOX. Currently, vaccines approved by WHO for use against MPOX are replicating (ACAM2000), low replicating (LC16m8), and non-replicating (MVA-BN). Although vaccines are accessible, investigations have demonstrated that smallpox vaccination is approximately 85% efficient in inhibiting MPOX. In addition, developing new vaccine methods against MPOX can help prevent this infection. To recognize the most efficient vaccine, it is essential to assess effects, including reactogenicity, safety, cytotoxicity effect, and vaccine-associated side effects, especially for high-risk and vulnerable people. Recently, several orthopoxvirus vaccines have been produced and are being evaluated. Hence, this review aims to provide an overview of the efforts dedicated to several types of vaccine candidates with different strategies for MPOX, including inactivated, live-attenuated, virus-like particles (VLPs), recombinant protein, nucleic acid, and nanoparticle-based vaccines, which are being developed and launched.

The assessment on cross immunity with smallpox virus and antiviral drug sensitivity of the isolated mpox virus strain WIBP-MPXV-001 in China

Since May 2022, human mpox cases have increased unexpectedly in non-endemic countries. The first imported case of human mpox in Hong Kong was reported in September 2022. Here we report the isolation and identification of MPXV from the vesicle swabs of this patient. In this research, the vesicle swabs were inoculated in Vero and Vero E6 cells. In addition to observing cytopathic effects (CPEs) in Vero or Vero E6 cells, the isolated virus was identified as mpox virus (MPXV) using quantitative Real-Time PCR (RT-PCR), transmission electron microscopy, and high-throughput sequencing. The experiment also assessed the cross-protective efficacy of sera from the smallpox vaccinated population and preliminarily assessed the inhibitory effect of anti-smallpox virus drugs against MPXV. CPEs can be observed on Vero E6 cells at 24 hours and Vero cells at 48 hours. The virus particles could be observed by transmission electron microscope, showing typical orthopoxvirus morphology. In addition, F3L and ATI genes which from MPXV A39R, B2R, HA genes which from orthopoxvirus were confirmed by conventional PCR and Sanger sequencing. The next generation sequencing (NGS) suggests that the MPXV strain belongs to B.1 branch of the West African linage, and has a highly identity with the sequence of the 2022 ongoing outbreak. PRNT₅₀ results showed that 26.7% of sera from individuals born before 1981 who had been immunized with smallpox were positive, but no MPXV-neutralizing antibodies were found in sera from individuals born later. All four anti-smallpox virus drugs evaluated demonstrated inhibition of mpox virus.

Monkeypox virus quadrivalent mRNA vaccine induces immune response and protects against vaccinia virus

Monkeypox has been declared a public health emergency by the World Health Organization. There is an urgent need for efficient and safe vaccines against the monkeypox virus (MPXV) in response to the rapidly spreading monkeypox epidemic. In the age of COVID-19, mRNA vaccines have been highly successful and emerged as platforms enabling rapid development and large-scale preparation. Here, we develop two MPXV quadrivalent mRNA vaccines, named mRNA-A-LNP and mRNA-B-LNP, based on two intracellular mature virus specific proteins (A29L and M1R) and two extracellular enveloped virus specific proteins (A35R and B6R). By administering mRNA-A-LNP and mRNA-B-LNP intramuscularly twice, mice induce MPXV specific IgG antibodies and potent vaccinia virus (VACV) specific neutralizing antibodies. Further, it elicits efficient MPXV specific Th-1 biased cellular immunity, as well as durable effector memory T and germinal center B cell responses in mice. In addition, two doses of mRNA-A-LNP and mRNA-B-LNP are protective against the VACV challenge in mice. And, the passive transfer of sera from mRNA-A-LNP and mRNA-B-LNP-immunized mice protects nude mice against the VACV challenge. Overall, our results demonstrate that mRNA-A-LNP and mRNA-B-LNP appear to be safe and effective vaccine candidates against monkeypox epidemics, as well as against outbreaks caused by other orthopoxviruses, including the smallpox virus.

Mpox vaccine and infection-driven human immune signatures

Background

Mpox (formerly known as monkeypox) outbreaks outside endemic areas peaked in July 2022, infecting > 85,000 people and raising concerns about our preparedness against this emerging viral pathogen. Licensed and approved for mpox, the JYNNEOS vaccine has fewer side effects than previous smallpox vaccines and demonstrated efficacy against mpox infection in humans. Comparing JYNNEOS vaccine- and mpox-induced immunity is imperative to evaluate JYNNEOS' immunogenicity and inform vaccine administration and design.

Methods

We examined the polyclonal serum (ELISA) and single B cell (heavy chain gene and transcriptome data) antibody repertoires and T cells (AIM and ICS assays) induced by the JYNNEOS vaccine as well as mpox infection.

Findings

Gene-level plasmablast and antibody responses were negligible and JYNNEOS vaccinee sera displayed minimal binding to recombinant mpox proteins and native proteins from the 2022 outbreak strain. In contrast, recent mpox infection (within 20-102 days) induced robust serum antibody responses to A29L, A35R, A33R, B18R, and A30L, and to native mpox proteins, compared to vaccinees. JYNNEOS vaccine recipients presented comparable CD4 and CD8 T cell responses against orthopox peptides to those observed after mpox infection.

Interpretation

JYNNEOS immunization does not elicit a robust B cell response, and its immunogenicity may be mediated by T cells.

Funding

Research reported in this publication was supported, in part, by the National Cancer Institute of the National Institutes of Health under Award Number U54CA267776, U19AI168631(VS), as well as institutional funds from the Icahn School of Medicine.

Monkeypox clinical disease: Literature review and a tool proposal for the monitoring of cases and contacts

The human monkeypox disease has mainly been described in Western and Central Africa. Since May 2022, the monkeypox virus has been spreading worldwide in a new epidemiological pattern, where cases result from person-to-person transmission, and develop clinically milder or less typical illness than during previous outbreaks in endemic areas. The newly-emerging monkeypox disease needs to be described over the long term, to improve cases definitions, to implement prompt control measures against epidemics, and to provide supportive care. Hence, we first conducted a review of historical and recent outbreaks to define the full clinical spectrum of the monkeypox disease and its course known so far. Then, we built a self-administrated questionnaire collecting daily symptoms of the monkeypox infection to follow cases and their contacts, even remotely. This tool will assist in the management of cases, the surveillance of contacts, and the conduct of clinical studies.

Immunization of mice with vaccinia virus Tiantan strain yields antibodies cross-reactive with protective antigens of monkeypox virus

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The first study describing the cross-reactivity of antibodies elicited by a Chinese smallpox vaccine against MPXV.

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Mice immunized with vaccinia virus Tiantan strain yield antibodies cross-reactive with MPXV protective antigens.

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Cross-reactivities of VTT-elicited antibodies against monkeypox protective antigens are ranging from 33% to 94%.

Immunoinformatics design of multivalent epitope vaccine against monkeypox virus and its variants using membrane-bound, enveloped, and extracellular proteins as targets

Introduction

The current monkeypox (MPX) outbreak, caused by the monkeypox virus (MPXV), has turned into a global concern, with over 59,000 infection cases and 23 deaths worldwide.

Objectives

Herein, we aimed to exploit robust immunoinformatics approach, targeting membrane-bound, enveloped, and extracellular proteins of MPXV to formulate a chimeric antigen. Such a strategy could similarly be applied for identifying immunodominant epitopes and designing multi-epitope vaccine ensembles in other pathogens responsible for chronic pathologies that are difficult to intervene against.

Methods

A reverse vaccinology pipeline was used to select 11 potential vaccine candidates, which were screened and mapped to predict immunodominant B-cell and T-cell epitopes. The finalized epitopes were merged with the aid of suitable linkers, an adjuvant (Resuscitation-promoting factor), a PADRE sequence (13 aa), and an HIV TAT sequence (11 aa) to formulate a multivalent epitope vaccine. Bioinformatics tools were employed to carry out codon adaptation and computational cloning. The tertiary structure of the chimeric vaccine construct was modeled via I-TASSER, and its interaction with Toll-like receptor 4 (TLR4) was evaluated using molecular docking and molecular dynamics simulation. C-ImmSim server was implemented to examine the immune response against the designed multi-epitope antigen.

Results and discussion

The designed chimeric vaccine construct included 21 immunodominant epitopes (six B-cell, eight cytotoxic T lymphocyte, and seven helper T-lymphocyte) and is predicted non-allergen, antigenic, soluble, with suitable physicochemical features, that can promote cross-protection among the MPXV strains. The selected epitopes indicated a wide global population coverage (93.62%). Most finalized epitopes have 70%-100% sequence similarity with the experimentally validated immune epitopes of the vaccinia virus, which can be helpful in the speedy progression of vaccine design. Lastly, molecular docking and molecular dynamics simulation computed stable and energetically favourable interaction between the putative antigen and TLR4.

Conclusion

Our results show that the multi-epitope vaccine might elicit cellular and humoral immune responses and could be a potential vaccine candidate against the MPXV infection. Further experimental testing of the proposed vaccine is warranted to validate its safety and efficacy profile.

Defining antigen targets to dissect vaccinia virus and monkeypox virus-specific T cell responses in humans

The monkeypox virus (MPXV) outbreak confirmed in May 2022 in non-endemic countries is raising concern about the pandemic potential of novel orthopoxviruses. Little is known regarding MPXV immunity in the context of MPXV infection or vaccination with vaccinia-based vaccines (VACV). As with vaccinia, T cells are likely to provide an important contribution to overall immunity to MPXV. Here, we leveraged the epitope information available in the Immune Epitope Database (IEDB) on VACV to predict potential MPXV targets recognized by CD4⁺ and CD8⁺ T cell responses. We found a high degree of conservation between VACV epitopes and MPXV and defined T cell immunodominant targets. These analyses enabled the design of peptide pools able to experimentally detect VACV-specific T cell responses and MPXV cross-reactive T cells in a cohort of vaccinated individuals. Our findings will facilitate the monitoring of cellular immunity following MPXV infection and vaccination.

Monkeypox: Immune response, vaccination and preventive efforts

Infectious threats to humans are continuously emerging. The 2022 worldwide monkeypox outbreak is the latest of these threats with the virus rapidly spreading to 106 countries by the end of September 2022. The burden of the ongoing monkeypox outbreak is manifested by 68,000 cumulative confirmed cases and 26 deaths. Although monkeypox is usually a self-limited disease, patients can suffer from extremely painful skin lesions and complications can occur with reported mortalities. The antigenic similarity between the smallpox virus (variola virus) and monkeypox virus can be utilized to prevent monkeypox using smallpox vaccines; treatment is also based on antivirals initially designed to treat smallpox. However, further studies are needed to fully decipher the immune response to monkeypox virus and the immune evasion mechanisms. In this review we provide an up-to-date discussion of the current state of knowledge regarding monkeypox virus with a special focus on innate immune response, immune evasion mechanisms and vaccination against the virus.

Comparison of Biological, Pharmacological Characteristics, Indications, Contraindications and Adverse Effects of JYNNEOS and ACAM2000 Monkeypox Vaccines

Human monkeypox is an emerging viral zoonotic disease, that has caused highly distinctive, challenging and threatening problems worldwide. The US Food and Drug Administration (FDA) has given interim authorization for the JYNNEOS and ACAM2000 vaccines for the outbreak of monkeypox 2022. The present study aims to highlight the globally derived evidence about the biological and pharmacological features, indications, contraindications and adverse effects of JYNNEOS and ACAM2000 vaccines. Initially, 82 documents were selected and, finally, 14 fact sheets, documents and international organizations were included. The data were recorded from the World Health Organization (WHO), Centers for Disease Control and Prevention (CDC), Food and Drug Administration (FDA) USA, ISI-Web of Science, PubMed, EMBASE and Scopus. The data revealed that the JYNNEOS vaccine has been recommended to children, adults, females during pregnancy and people of all age groups with a dose of 0.5 mL, and the complete vaccination cost per person is about USD 115. It provides immunogenicity, and the mean titer of neutralizing antibodies was 153.5. However, the ACAM2000 vaccine is contraindicated in infants and pregnant females, and recommended to people over 18 years of age and older, with a single dose of 0.0025 mL, and a cost of about USD 139. ACAM2000 provides immunogenicity, and the mean titer of neutralizing antibodies was 79.3. The JYNNEOS vaccine has mild adverse effects including pain, redness, swelling or itching at the site of the vaccine shot, fever, fatigue, headache, nausea and muscle pain. However, the ACAM2000 vaccine can cause pain, redness, edema, headache, fever, fatigue, muscle pain, body ache, nausea, vomiting, diarrhea, shortness of breath and increased risk of myopericarditis and cardiomyopathy. The evidence supports the view that both vaccines are beneficial, but the overall impact of JYNNEOS is better than that of ACAM2000.