Evaluation of Cross-Immunity to the Mpox Virus Due to Historic Smallpox Vaccination

Global perspectives on smallpox vaccine against monkeypox: a comprehensive meta-analysis and systematic review of effectiveness, protection, safety and cross-immunogenicity

A large outbreak of monkeypox occurred in 2022, and most people lack immunity to orthopoxvirus. Smallpox vaccination is essential for preventing further smallpox outbreaks. This study evaluated the effectiveness, protection, safety, and cross-immunogenicity of smallpox vaccine in preventing monkeypox infection. PubMed, Embase, Scopus, and Web of Science were searched from database inception to 10 March 2024. We included studies involving "monkeypox virus" and "vaccinations", and excluded reviews, animal studies, and articles with missing or duplicate data. A total of 37 studies with 57,693 participants were included in the final analysis. The effectiveness data showed that monkeypox infection rates were lower in the smallpox-vaccinated group than in the unvaccinated group (risk ratio [RR]: 0.46; 95% confidence interval [CI]: 0.31-0.68). The protection data showed that smallpox vaccination effectively reduced the risk of severe monkeypox infection (RR: 0.61; 95% CI: 0.42-0.87). Third-generation vaccines showed greater efficacy (RR: 0.36, 95% CI: 0.22-0.56) than first-generation vaccines. The number of doses of smallpox vaccine has no significant effect on monkeypox. Safety data showed that adverse reactions after smallpox vaccination were mainly mild and included local erythema, swelling, induration, itching, and pain. Meanwhile, we found that smallpox vaccination could induce the production of neutralizing antibodies against monkeypox. Our findings offer compelling evidence supporting the clinical application of the smallpox vaccine for preventing monkeypox and advocate that high-risk groups should be prioritized for receiving one dose of the smallpox vaccine if the vaccine stockpile is low.

Comparative Analysis of 2022 Outbreak MPXV and Previous Clade II MPXV

The 2022-2024 outbreak of MPOX is an important worldwide public health issue that has triggered significant concerns in the scientific community. MPOX is caused by monkeypox virus (MPXV) belonging to the Poxviridae family. The study of MPXV presents a multifaceted challenge due to the diverse viral formThis study was supported by ISIDORe consortium and Agencia Estatal de Investigación.s produced by this pathogen. Notably the intracellular mature viruses (MVs) primarily contribute to localized lesions and host-to-host transmission, while the extracellular enveloped viruses (EVs) are associated with systemic infection. Clinically, MPOX manifests as a vesiculopustular rash that initially emerges on the face and trunk, subsequently spreading throughout the body, with heightened severity observed in immunocompromised individuals. Results obtained in this manuscript indicate that the 2022 outbreak MPXV has a significantly slower viral cycle compared with previous Clade II strains, with WRAIR 7-61 being more intermediate and USA 2003 producing highest viral titers. Additionally, proteomic and phospho-proteomic analysis displays differences in protein expression between these three strains. These findings highlight key differences between the current Lineage B.1 MPXV and previous strains. Further studies will be undertaken to demonstrate if these differences are important for the apparent increased human-to-human transmission mechanisms observed in the Clade IIb MPXV outbreak.

A seroprevalence study indicates a high proportion of clinically undiagnosed MPXV infections in men who have sex with men in Berlin, Germany

INTRODUCTION

During the mpox outbreak in 2022, the highest number of cases in Germany were registered in Berlin, almost all of them in men who have sex with men (MSM). However, the frequency of clinically undiagnosed infections is unknown.

METHODS

A cross-sectional study was conducted among MSM in Berlin, Germany. Participants were recruited from private practices and community-based checkpoints specialised in HIV and STI care for MSM. They were asked to complete an online questionnaire on socio-demographic data, mpox diagnosis, vaccination history and sexual behaviour, and to provide a blood sample for serological analysis. The samples were tested for antibodies against a range of antigens to distinguish between antibodies induced by mpox infection and MVA vaccination, with pre-immune sera from childhood smallpox vaccination as a confounding factor. Associations of behavioural variables with reported and suspected mpox diagnosis as the outcome were tested using univariable and multivariable logistic regression models.

RESULTS

Between the 11th April and 1st July 2023, 1,119 participants were recruited in eight private practices and two community-based checkpoints in Berlin. All participants provided a blood sample for serological testing. Information for the online questionnaire was provided by 728 participants; core data on age and mpox history for participants who did not provide questionnaire data were provided by the practices for an additional 218 participants. A previous diagnosis of mpox was reported for/by 70 participants (7.4%). Using a conservative and strict case definition, we serologically identified an additional 91 individuals with suspected undiagnosed mpox infection. Individuals with reported or suspected mpox infections reported more condomless anal sex partners in the past 3 months (OR = 5.93; 95% CI 2.10-18.35 for 5-10 partners; OR = 9.53; 95% CI 2.72-37.54 for > 10 partners) and were more likely to report sexual contact with partners diagnosed with mpox (OR = 2.87; 95% CI 1.39-5.84).

CONCLUSION

A substantial proportion of mpox infections were clinically undiagnosed. The number of condomless anal sex partners was strongly associated with both confirmed and suspected undiagnosed mpox infection. Therefore, mpox control measures based on clinical diagnosis of mpox are likely to have limited effectiveness in preventing mpox transmission in outbreak situations because many infections remain unrecognised and undiagnosed.

A Label-free Optical Biosensor-Based Point-of-Care Test for the Rapid Detection of Monkeypox Virus

Diagnostic approaches that combine the high sensitivity and specificity of laboratory-based digital detection with the ease of use and affordability of point-of-care (POC) technologies could revolutionize disease diagnostics. This is especially true in infectious disease diagnostics, where rapid and accurate pathogen detection is critical to curbing the spread of disease. We have pioneered an innovative label-free digital detection platform that utilizes Interferometric Reflectance Imaging Sensor (IRIS) technology. IRIS leverages light interference from an optically transparent thin film, eliminating the need for complex optical resonances to enhance the signal by harnessing light interference and the power of signal averaging in shot-noise-limited operation to achieve virtually unlimited sensitivity. In our latest work, we have further improved our previous 'Single-Particle' IRIS (SP-IRIS) technology by allowing the construction of the optical signature of target nanoparticles (whole virus) from a single image. This new platform, 'Pixel-Diversity' IRIS (PD-IRIS), eliminated the need for z-scan acquisition, required in SP-IRIS, a time-consuming and expensive process, and made our technology more applicable to POC settings. Using PD-IRIS, we quantitatively detected the Monkeypox virus (MPXV), the etiological agent for Monkeypox (Mpox) infection. MPXV was captured by anti-A29 monoclonal antibody (mAb 69-126-3) on Protein G spots on the sensor chips and were detected at a limit-of-detection (LOD) - of 200 PFU/ml (~3.3 attomolar). PD-IRIS was superior to the laboratory-based ELISA (LOD - 1800 PFU/mL) used as a comparator. The specificity of PD-IRIS in MPXV detection was demonstrated using Herpes simplex virus, type 1 (HSV-1), and Cowpox virus (CPXV). This work establishes the effectiveness of PD-IRIS and opens possibilities for its advancement in clinical diagnostics of Mpox at POC. Moreover, PD-IRIS is a modular technology that can be adapted for the multiplex detection of pathogens for which high-affinity ligands are available that can bind their surface antigens to capture them on the sensor surface.

An overview on mRNA-based vaccines to prevent monkeypox infection

The human monkeypox virus (Mpox) is classified as a member of the Poxviridae family and belongs to the Orthopoxvirus genus. Mpox possesses double-stranded DNA, and there are two known genetic clades: those originating in West Africa and the Congo Basin, commonly known as Central African clades. Mpox may be treated with either the vaccinia vaccination or the therapeutics. Modifying the smallpox vaccine for treating and preventing Mpox has shown to be beneficial because of the strong link between smallpox and Mpox viruses and their categorization in the same family. Cross-protection against Mpox is effective with two Food and Drug Administration (FDA)-approved smallpox vaccines (ACAM2000 and JYNNEOSTM). However, ACAM2000 has the potential for significant adverse effects, such as cardiac issues, whereas JYNNEOS has a lower risk profile. Moreover, Mpox has managed to resurface, although with modified characteristics, due to the discontinuation and cessation of the smallpox vaccine for 40 years. The safety and efficacy of the two leading mRNA vaccines against SARS-CoV-2 and its many variants have been shown in clinical trials and subsequent data analysis. This first mRNA treatment model involves injecting patients with messenger RNA to produce target proteins and elicit an immunological response. High potency, the possibility of safe administration, low-cost manufacture, and quick development is just a few of the benefits of RNA-based vaccines that pave the way for a viable alternative to conventional vaccines. When protecting against Mpox infection, mRNA vaccines are pretty efficient and may one day replace the present whole-virus vaccines. Therefore, the purpose of this article is to provide a synopsis of the ongoing research, development, and testing of an mRNA vaccine against Mpox.

Immunogenicity and reactogenicity of modified vaccinia Ankara pre-exposure vaccination against mpox according to previous smallpox vaccine exposure and HIV infection: prospective cohort study

Background

Pre-exposure vaccination with MVA-BN has been widely used against mpox to contain the 2022 outbreak. Many countries have defined prioritized strategies, administering a single dose to those historically vaccinated for smallpox, to achieve quickly adequate coverage in front of low supplies. Using epidemiological models, real-life effectiveness was estimated at approximately 36%-86%, but no clinical trials were performed. Few data on MVA-BN immunogenicity are currently available, and there are no established correlates of protection. Immunological response in PLWH in the context of the 2022 outbreak was also poorly described.

Methods

Blood samples were collected from participants eligible for pre-exposure MVA-BN vaccination before (T1) receiving a full course of vaccine (single-dose for vaccine-experienced or smallpox-primed and two-dose for smallpox vaccine-naïve or smallpox non-primed) and one month after the last dose (T2 and T3, respectively). MPXV-specific IgGs were measured by in-house immunofluorescence assay, using 1:20 as screening dilution, MPXV-specific nAbs by 50% plaque reduction neutralization test (PRNT50, starting dilution 1:10), and IFN-γ-producing specific T cells to MVA-BN vaccine, by ELISpot assay. Paired or unpaired t-test and Wilcoxon or Mann-Whitney test were used to analyse IgG and nAbs, and T-cell response, as appropriate. The probability of IgG and nAb response in vaccine-experienced vs. vaccine-naïve was estimated in participants not reactive at T1. The McNemar test was used to evaluate vaccination's effect on humoral response both overall and by smallpox vaccination history. In participants who were not reactive at T1, the proportion of becoming responders one month after full-cycle completion by exposure groups was compared by logistic regression and then analysed by HIV status strata (interaction test). The response was also examined in continuous, and the Average Treatment Effect (ATE) of the difference from baseline to schedule completion according to previous smallpox vaccination was estimated after weighting for HIV using a linear regression model. Self-reports of adverse effects following immunization (AEFIs) were prospectively collected after the first MVA-BN dose (T1). Systemic (S-AEFIs: fatigue, myalgia, headache, GI effects, chills) and local (L-AEFIs: redness, swelling, pain) AEFIs were graded as absent (grade 0), mild (1), moderate (2), or severe (3). The maximum level of severity for S-AEFIs and L-AEFIs ever experienced over the 30 days post-dose by vaccination exposure groups were analysed using a univariable multinomial logistic regression model and after adjusting for HIV status; for each of the symptoms, we also compared the mean duration by exposure group using an unpaired t-test.

Findings

Among the 164 participants included, 90 (54.8%) were smallpox vaccine-experienced. Median age was 49 years (IQR 41-55). Among the 76 (46%) PLWH, 76% had a CD4 count >500 cells/μL. There was evidence that both the IgG and nAbs titers increased after administration of the MVA-BN vaccine. However, there was no evidence for a difference in the potential mean change in humoral response from baseline to the completion of a full cycle when comparing primed vs. non-primed participants. Similarly, there was no evidence for a difference in the seroconversion rate after full cycle vaccination in the subset of participants not reactive for nAbs at T1 (p = 1.00 by Fisher's exact test). In this same analysis and for the nAbs outcome, there was some evidence of negative effect modification by HIV (interaction p-value = 0.17) as primed people living with HIV (PLWH) showed a lower probability of seroconversion vs. non-primed, and the opposite was seen in PLWoH. When evaluating the response in continuous, we observed an increase in T-cell response after MVA-BN vaccination in both primed and non-primed. There was evidence for a larger increase when using the 2-dose vs. one-dose strategy with a mean difference of -2.01 log2 (p ≤ 0.0001), after controlling for HIV. No evidence for a difference in the risk of developing any AEFIs of any grade were observed by exposure group, except for the lower risk of grade 2 (moderate) fatigue, induration and local pain which was lower in primed vs. non-primed [OR 0.26 (0.08-0.92), p = 0.037; OR 0.30 (0.10-0.88), p = 0.029 and OR 0.19 (0.05-0.73), p = 0.015, respectively]. No evidence for a difference in symptom duration was also detected between the groups.

Interpretation

The evaluation of the humoral and cellular response one month after the completion of the vaccination cycle suggested that MVA-BN is immunogenic and that the administration of a two-dose schedule is preferable regardless of the previous smallpox vaccination history, especially in PLWH, to maximize nAbs response. MVA-BN was safe as well tolerated, with grade 2 reactogenicity higher after the first administration in vaccine-naïve than in vaccine-experienced individuals, but with no evidence for a difference in the duration of these adverse effects. Further studies are needed to evaluate the long-term duration of immunity and to establish specific correlates of protection.

Funding

The study was supported by the National Institute for Infectious Disease Lazzaro Spallanzani IRCCS "Advanced grant 5 × 1000, 2021" and by the Italian Ministry of Health "Ricerca Corrente Linea 2".

T Cell Responses against Orthopoxviruses in HIV-Positive Patients

A global outbreak of predominantly sexually transmitted mpox infections, outside endemic regions, was reported in May 2022. Thereafter, risk groups were vaccinated against smallpox, a structurally related orthopoxvirus. In the current study, we analyzed T cell responses against peptides derived from orthopoxviruses in 33 HIV-positive patients after two vaccinations against smallpox and in 10 patients after mpox infection. We established an ELISpot assay, detecting either the secretion of the pro-inflammatory cytokine interferon (IFN)-γ or interleukin (IL)-2. After vaccination, 21 out of 33 patients (64%) showed specific IFN-γ secretion and 18 (55%) specific IL-2 secretion, defined as >3-fold higher specific value than negative control and at least 4 spots above the negative control. After mpox infection, all patients showed specific IFN-γ secretion and 7 out of 10 (70%) IL-2 secretion. In vaccinated patients, IFN-γ responses were significantly lower than in patients with mpox infection (median response 4.5 vs. 21.0 spots, p < 0.001). The same trend was observed for IL-2 responses. After mpox infection, IL-2 ELISpot results positively correlated with CD8+ T cells (p < 0.05). Thus, T cell responses were detectable in two thirds of HIV-positive patients after vaccination and were even more abundant and vigorous after mpox infection.

Assessment of Knowledge and Concern of People Living with HIV Regarding Human Mpox and Vaccination

INTRODUCTION

Mpox virus is an orthopoxvirus that causes the zoonotic infectious disease known as mpox. The disease can also spread from humans to humans. It can be transmitted through contact with bodily fluids, lesions on the skin, or internal mucosal surfaces.

METHOD

The number of mpox cases increased during the COVID-19 pandemic. Early diagnosis and prompt management of mpox are critical in people living with HIV (PLHIV). In this study, a cross-sectional survey was conducted among PLHIV followed at the outpatient clinic between 20 April-20 August 2023. A questionnaire was used to assess the knowledge and anxiety levels of patients as well as their opinions about vaccination against mpox. The severity of symptoms in the past two weeks was assessed using the Generalised Anxiety Disorder 7-item scale. A total of 203 PLHIV were interviewed for this survey study.

RESULT

The mean age was 39.37±11.93. The majority of them were male (86.7%), and 41.4% were men who have sex with men (MSM). Only 21 of the surveyed participants (10.4%) had a "good knowledge" score about mpox. The mean knowledge score on human Mpox was 2.05 (min:0-max:8), and 107 (52.7%) had a score of 0.

CONCLUSION

The future study should focus on continuous education, promoting awareness through programs and establishing measures to successfully overcome identified variables that contribute to mpox pandemic understanding and attitudes. Applying the lessons learned from the COVID-19 pandemic will help the management of mpox virus.