14. Mpox (orthopoxvirus)

Mpox is an infectious disease caused by the monkeypox virus. It classically presents with a prodrome of fever, aches and lymphadenopathy followed by a characteristic centrifugal rash. Systemic prodromal symptoms may also include intense fatigue, headache, muscle pain, backache, chills and sore throat, and last for one to three days before rash onset. The rash lesions first appear on the face and in the mouth and move to distal extremities. These lesions usually progress through four stages: macules, papules, fluid-filled vesicles and pustular pustules, eventually forming scabs. The mpox rash resembles that of other common infections such as foot-and-mouth disease, varicella (chickenpox), herpes simplex, syphilis and molluscum contagiosum. Coinfections can occur, particularly with other sexually transmitted infections. Monkeypox virus can be detected by PCR testing from swabs of lesions.

The typical incubation period is seven to 14 days, with a range of two to 21 days or longer.[1] This period can be shorter with invasive exposure, such as through broken skin or mucosal surfaces. An infected individual is infectious from onset of the first symptoms (usually fever but occasionally a rash) and until all the rash lesions crust and fall off over a period of two to three weeks. Scabs may still contain infectious virus. Mpox subclade IIb is generally mild and self-limiting, lasting two to four weeks. Severe illness, which can be fatal, is more common in children, and in pregnant or immunocompromised individuals, such as those living with advanced HIV infection. Clade I infections are associated with more severe disease and death. The mortality rate of the subclade Ib outbreak in Africa is around 4 percent.

Mpox virus does not spread easily between individuals. Human to human transmission occurs primarily through close, direct physical contact with infected skin, mucosal lesions and body fluids. It can also be spread by respiratory droplets during prolonged face-to-face contact. Infrequent transmission has been reported through contaminated materials like clothing, towels or bedding. Viral shedding has been reported in semen and saliva, notably for longer duration in people who are immunocompromised due to HIV infection.[2,3] Mpox can also be transmitted through close contact with infected animals.[1]

During the 2022-23 outbreak of subclade IIb, presentations were often atypical. Prodromal systemic symptoms may have been absent, blunted or develop after the onset of rash. Frequently, rash lesions were confined to anogenital skin, oropharynx or rectal mucosa, at various stages of evolution and atypical progression, or with only a single lesion. Most cases were mild and presented to sexual health services. Spontaneous and complete recovery typically occurred within three weeks. Complications included secondary cellulitis (reported in around 11 percent of cases), severe proctitis, odynophagia, tonsillitis, epiglottitis, pneumonia, sepsis, encephalitis, and keratitis that could lead to vision loss.

Data is limited around mpox infection in pregnancy, but case reports from DRC associated vertical transmission with miscarriage and fetal infection resulting in stillbirth.[4,5]

See the Mpox chapter of Communicable Disease Control Manual for further information.

The first human monkeypox (renamed mpox) case was reported in 1970. Cases and occasional outbreaks were successively reported in 11 countries of Central and West Africa. Occasional travel-associated cases and small clusters have occurred in nonendemic countries over the past decades. An increase in cases has been seen in Nigeria since 2017.

In May 2022, three separate incidents of clade IIb mpox were identified in the UK. The first case was a recognised travel-associated case from Nigeria and did not lead to further spread. The second case was not related to travel and indicated local transmission. With over 15,000 confirmed cases of clade IIb reported in 74 non-endemic countries across the six WHO regions, including New Zealand and Australia, WHO declared the outbreak a Public Health Emergency of International Concern (PHEIC) on the 23 July 2022.[1] This PHEIC was declared over in May 2023, but clade II infections continue to be notified globally, including in the Western Pacific region and in particular, with an increase in cases in Australia in July 2024.

During 2022-2023, the ten most affected countries were in the Americas, Europe and the UK accounting for 86 percent of the global clade IIb cases. Transmission was mainly among young males who identify as gay, bisexual and other men-who-have-sex-with-men (GBMSM) through sexual encounters (96.4 percent of cases with known sexual orientation and 86.9 percent sexual encounters, median age 34 years).[6] Sporadic cases were also reported among household members, nonsexual, heterosexual and pregnant contacts, and children (1.3 percent of cases were children).[7] Most infections in health workers occurred in the community through sexual encounters, but approximately 10 percent reported transmission through occupational exposure.[6] 

On 14 August 2024, WHO declared second mpox PHEIC in response to rising cases and deaths, predominantly due to the new clade Ib subvariant. Subclades Ia and Ib had spread from the Democratic Republic of Congo (DRC), where 96.3 percent of cases and 96.3 percent of deaths had occurred in 2024. Fifteen African Union member states reported cases, including Burundi, Cameroon, the Central African Republic, Egypt, Morocco, Rwanda, South Africa, Sudan and Uganda. By 28 July 2024, reported cases had increased by 160 percent and mpox deaths by 19 percent compared with the same period in 2023. Active outbreaks of clade Ia, Ib and II mpox were reported in additional African countries in differing contexts. An outbreak of subclade IIb infections emerged in May 2024 in South Africa causing high mortality in immunocompromised individuals.[1] Subclade Ia mpox is endemic in DRC and primarily affects children aged under 15 years through non-sexual contact with infected household members or animals. Cases of subclade Ib are predominantly adults presumed to be transmitted via sexual contact, but cases have been reported children aged under 5 years. The first case of clade Ib outside of Africa was detected in Sweden in an individual who had travelled from central Africa in August 2024. Since clade Ib risk is in different age groups in Africa, it may not confer the same epidemiological risk in New Zealand as the clade IIb outbreak.

For status of current cases see WHO 2022-2024 Mpox (Monkeypox) Outbreak: Global trends website.

The first confirmed case of mpox during the 2022-2023 clade II outbreak was reported in New Zealand on 7 July 2022 and a second unrelated confirmed case was reported on 12 July 2022. By 15 December 2022, 40 cases had been reported to WHO. Nine cases were acquired overseas and 31 were identified as community transmission associated with attendance at sex-on-site venues. By 15 August 2024, 53 cases had been notified in total. An increase in cases was linked with the Queenstown Winter Pride festival, and as of 20 September 2024, a further 11 cases had been reported. No clade Ib cases have been reported to date in New Zealand.

Funded mpox vaccine

The mpox (orthopoxvirus) vaccine (MPV) is available in New Zealand for prevention of mpox infection. Initially from late 2022, it was accessed as part of the National Immunisation Programme under section 29 of the Medicine Act 1981. Provisional approval for use in adults was granted by Medsafe in September 2024.

Data on the efficacy of MPV against smallpox or mpox in humans is limited. Due to the eradication of smallpox and the rarity of mpox—previously seen only in West and Central Africa—immunogenicity has been used as a proxy for efficacy in clinical trials in humans. Preclinical studies were used to demonstrate that the vaccine protects against lethal mpox challenges in primates.[9] and related viruses in other animals.

Another challenge is that the transmission patterns in the 2022 subclade IIb outbreak, which primarily affected GBMSM including those living with HIV, differed from earlier African outbreaks that predominantly involved children through household and zoonotic transmission.[10] While more data has become available from the subclade IIb outbreak, information on the vaccine's efficacy against clade I remains limited, but WHO anticipates that MPV will demonstrate effectiveness against both clade I and II infections (although the demographics differ with more children affected by clade I and subclade Ib).[1]

Immunogenicity

Most of the existing immunogenicity data has primarily concentrated on neutralizing antibody activity. There is no defined correlate of protection but antibody levels appear to correlate well with effectiveness.[1] Significant correlation between vaccinia-binding antibody titres and vaccine effectiveness was shown by a meta-analysis.[11] Additionally, T cell cross-protection between mpox clades is possible. Mpox virus clade I and the 2022 outbreak clade IIb share 71 percent of the T cell epitopes with the vaccinia virus used in the live smallpox vaccine and modified in the MVA-BN vaccine.[12]

A phase 3 placebo-controlled trial showed seroconversion rates of 99.8 percent at two weeks after dose two of MPV. Just over 4,000 healthy male and female recipients aged 18–40 years received two doses of MPV subcutaneously (SC) four weeks apart.[13]

HIV infection and prior smallpox vaccination

Comparable antibody responses to two doses of MPV, with no significant differences in neutralising antibody titres, were shown between 91 HIV-infected (CD4 cell count ≥350 cells/mm³) and 60 HIV-uninfected clinical trial participants.[14] A study (in preprint) in New York found that HIV status with CD4 cell counts over 250 cells/mm³ did not affect the response to MPV and that immunity was comparable between those with and without HIV when one-fifth dose was given intradermally.[15]

There is evidence in humans of cross-protection between smallpox vaccination and mpox. Surveillance data in DRC found that people born prior to 1980 who were vaccinated with live vaccinia-based smallpox vaccine had greater than five-fold reduction in mpox risk than those not previously vaccinated (VE against mpox of 68-88 percent).[1] But it is unclear what protection historical smallpox vaccination affords in those living with HIV.

In those with a history of vaccination with vaccinia (smallpox) vaccine, one dose of MPV induces a rapid antibody response and have comparable seroconversion rates whether given one or two doses of MPV.[14,16] A small study in New York (in preprint) found that the initial response to MPV induced comparable and robust antibody responses in those with or without prior smallpox (vaccinia) vaccination. But in vaccinia-naïve individuals, antibody levels after one dose waned to baseline within one year and had lower avidity than in those previously vaccinated.[15]

An Italian prospective cohort study in 164 adults found that two doses were preferable to maximise the neutralising antibody response, regardless of prior smallpox (vaccinia) vaccination, and particularly in those living with HIV.[17] Two doses of MPV in smallpox-naïve individuals induced a stronger cellular response than one dose in smallpox-primed individuals, but with no evidence of a difference in IgG and neutralising antibody responses. In participants living with well-controlled HIV infection, a neutralising antibody response was detected in fewer than half of the participants after one dose in those who had previously had smallpox vaccination than those who were smallpox-naïve after two doses of MPV. In this study, approximately half of the first doses were given subcutaneously, and all the second doses were given intradermally.[17] 

Effectiveness

Pre-exposure vaccination

Much of the recently published data on pre-exposure vaccinations investigated vaccine effectiveness after only one dose of MPV during the clade IIb outbreak due to limited vaccine availability to complete course. Further studies are needed in other populations with different modes of transmission, particularly in children, and to investigate the duration of protection.

A systematic review reported vaccine effectiveness of 76 percent (95% CI 64-88 percent; 12 studies) after one dose of MPV and after two doses to be 82 percent (72-92 percent; six studies).[18] The 33 studies included in the review predominantly vaccinated GBMSM between ages of 18-49 years during mid-2022.[18] Due to a shortage of vaccine doses, intradermal (ID) vaccination and a mix of SC and ID administration was used. One case-control study reported comparable vaccine effectiveness between SC, ID or a heterologous administration, with overall effectiveness of 85.9 percent (73.8-92.4 percent) after two doses.[18,19]

Breakthrough infection

Breakthrough infections, including asymptomatic and subclinical infections, have been reported following mpox vaccination.[20] In some cases, symptoms have arisen because the individual was unknowingly infected less than 21 days prior to vaccination.[21] Other cases occur several weeks after vaccination. For example, an mpox case in New Zealand occurred in an HIV-negative man 13 weeks after two subcutaneous doses of MPV. This case underscores the need for ongoing surveillance of individuals presenting with mpox-like symptoms, even if when fully vaccinated.[22]

Given the broad confidence intervals for effectiveness data, a Canadian observational study examined whether MPV reduced disease severity in breakthrough cases that occurred after one dose of MPV, where pre-exposure vaccination was received at least 14 days prior to symptom onset.[23] The study found that one dose of MPV was around 60 percent effective in mitigating the extent of clinical manifestations (eg, number of lesions and sites affected and other symptoms) in breakthrough mpox cases, regardless of HIV status.[23] Milder reinfections following wild-type mpox was also reported during the global outbreak.[1]

Post-exposure vaccination

Further research is needed to better understand the efficacy of MPV for post-exposure prophylaxis with vaccination. A systematic review and meta-analysis found that vaccine effectiveness of a single dose of MPV given for post-exposure prophylaxis against clade IIb was 20 percent (95% CI -24 to 65 percent) and lower than when given pre-exposure.[18] The wide confidence intervals were attributed to the fact that many studies included cases that occurred within the 14-day period after vaccination and due to immortal time biases in the unvaccinated group.[18] A Spanish study reported a vaccine effectiveness of 65 percent (22.9-88.0 percent) at seven or more days after vaccination, and 79.3 percent (33.3–100 percent) at 14 or more days post-vaccination, though it did not specify the time between exposure and vaccination.[18,24] When adjusting for immortal time bias, the vaccine effectiveness at less than 14 days post-exposure decreased from 78 percent to 19 percent.[25]

Nonetheless, post-exposure vaccination seems to offer some protection against mpox. An observational study in the US found that the incidence of mpox was significantly lower among individuals with known exposure or presumed exposure to mpox who received a single dose of MPV, given SC or ID, compared with those exposed and unvaccinated.[26] Of the 5,402 cases of mpox in males aged 18-49 years reported from 31 July to 3 September 2022, 4,606 cases (85.3 percent) were unvaccinated. The average incidence rate (cases per 100,000) was 14.3 times (95% CI 5.0–41.0) higher among unvaccinated individuals than for those who had received at least one dose of MPV at least 14 days prior to illness. Those who were vaccinated less than 13 days before illness or with an unknown vaccination date were excluded from the analysis.[26]

A small retrospective cohort study in France, of 108 participants given one dose of MPV post-exposure, found around 10 percent developed symptomatic breakthrough mpox within 21 days of mpox exposure.[27] In these cases, the clinical course was mild and none were hospitalised. Breakthrough infection was associated with sexual exposure (OR 12.5, 2.3-235, p = 0.018), to some extent immunosuppression, and to earlier vaccination post-exposure, potentially due to increased risk awareness or more intense mpox exposure.[27]

Transport according to the National Standards for Vaccine Storage and Transportation for Immunisation Providers 2017 (2nd edition).

Store unopened vials at +2 to +8°C for maximum of 24 weeks (if within approved shelf-life, dependent on prior storage at -50°C ± -10°C). Protect from light. Do not refreeze once thawed. Allow vaccine to reach room temperature (maximum +25°C) and swirl the vial gently for at least 30 seconds before use.

When used for intradermal administration, store opened vials at +2 to +8°C for a maximum of 8 hours from the first vial puncture.

Each dose of mpox vaccine (MPV) is 0.5 mL, administered by subcutaneous injection (see section ‎2.2.3). Two doses are given at least four weeks apart.

In circumstances where dose sparing is required (in the case of vaccine supply shortage), intradermal (ID) administration of 0.1 mL of MPV can be given as pre-exposure prophylaxis (see section 14.5 for criteria, this is off-label use requires a prescription from an authorised prescriber and preferably written consent). MPV can be administered intradermally in the volar aspect of the forearm, the upper arm or scapular. Depending on availability of vaccine, up to two doses are given from four weeks to 2 years apart.

The need for booster doses has not been established and are not recommended currently for those who have received two doses.

Co-administration with other vaccines

No studies to date have reported on coadministration of MPV (Jynneos) with other vaccines. Based on first principles, there is minimal risk of interference between MPV and other vaccines if given concurrently. Although the datasheet says to avoid concomitant administration with other vaccines and the attribution of adverse events is likely to be more difficult if given concurrently, this needs to be balanced with the risk of the individual not returning for other vaccinations. Concomitant administration of more than one vaccine can be considered at the same vaccination event alongside the delivery of MPV, with written consent.

MPV is recommended and funded for individuals aged 18 years or over who are at high risk for mpox infection. (See section 14.5.5 for children and adolescents). As it is a non-replicating viral, MPV can be given to individuals with immunocompromising medical conditions or therapy, including those living with HIV infection or receiving immunosuppressive medications (see section 14.5.4).

Adolescents aged under 18 years who meet the criteria for being at high risk of mpox exposure (as listed below) are highly recommended MPV vaccination, to be given under a prescription with consent. 

Pre-exposure vaccination is recommended for individuals at high risk of being exposed to mpox virus, includes those who are:

• at risk of occupational exposure to mpox
  • Laboratory staff working with orthopoxviruses
  • Health workers at risk of repeated exposures to patients with mpox
  • Sex workers, particularly for those with clients who are risk of exposure to mpox
• at risk of mpox infection during a local mpox outbreak, as determined by a medical officer of health
• at risk of mpox infection because they are:
  • gay, bisexual or other men who have sex with men (GBMSM), transgender or non-binary people who in the past 6 months have had one of the following:
    • A new diagnosis of a sexually transmitted disease
    • More than one sex partner
    • Sex at a commercial venue
    • Sex in association with a large public event in an area where mpox transmission is likely to occur
  • people living with HIV, if at risk of mpox exposure
  • sexual partners of those at increased risk of mpox infection.
• People who anticipate experiencing any of the above.

Post-exposure vaccination is recommended to be given within 4 days preferably (no later than 14 days) of exposure to a confirmed mpox case (see 14.8.1).

This vaccine is not available for travel purposes, to areas with an active outbreak, unless the individuals meet the criteria for being at high risk of infection, as listed above.

ID administration is only recommended for pre-exposure vaccination when vaccine supply is limited. If the SC route was used for the first dose, the vaccination course can be completed by ID injection for the second dose, and vice versa. This use is off-label and requires a prescription from an authorised prescriber and informed consent.

SC administration of the complete two-dose course is specifically recommended for:

• all individuals who are severely immunocompromised (see section 14.5.4)
• individuals with a history of keloid scarring
• children aged under 18 years (see section 14.5.5)

MPV should not be given ID to those specifically recommended SC administration. 

Mpox can be severe in pregnant people and have adverse effects on the fetus.[4,5] There is limited data on the use of MPV in human pregnancy or assessing the effects in breastfed infants. As a non-replicating virus vaccine, no theoretical concerns related to pregnancy contraindicate the use of MPV in pregnancy or while lactating. The adverse event profile is expected to be similar to that seen in non-pregnant recipients. No pregnancy-related adverse events were reported when MPV was used in fewer than 300 pregnancies and no safety concerns were raised when an MVA-vectored Ebola vaccine has been given inadvertently in pregnancy.[28] Animal studies did not identify any evidence of harm to the fetus when given during or prior to gestation.

It is unknown whether the vaccine virus, MVA-BN, is excreted in human milk but it is considered unlikely to infect the infant since it is unable to replicate in human cells.

It is preferable to avoid the use of MPV in pregnancy or while breastfeeding, however, pregnant or lactating individuals at high risk of exposure to mpox are recommended to discuss vaccination with health professionals. In these situations, the risk from exposure to mpox infection in pregnancy, such as risk of fetal loss, severe disease and peripartum transmission, should be discussed and written informed consent acquired. For individuals aged under 18 years who are pregnant or breastfeeding, a prescription from an authorised prescriber is also required.

Individuals with severe immunocompromise are recommended and prioritised to receive both MPV doses subcutaneously, given 4 weeks apart, for protection against potentially fatal disseminated mpox.

If indicated, MPV can be given to individuals with immunocompromising medical conditions or therapy, including those living with HIV infection or receiving immunosuppressive medications, because it contains a non-replicating virus. The immune response could be reduced in those who are severely immunosuppressed, it is important to reduce the risk of exposure and ensure close contacts are vaccinated if at risk.

Although MPV is not approved for use in infants and children aged under 18 years, several paediatric clinical studies using MVA-BN as a viral vector (including Ebola, TB and malaria vaccine candidates) have demonstrated an acceptable safety profile.[1] Small studies where children were administered MPV pre or post-mpox exposure also reported no serious adverse events and a favourable safety profile.[1]  Children and adolescents exposed to mpox are at high risk of severe mpox infection[5] and hence MPV is recommended for children at high risk of being infected. Give two doses subcutaneously at least four weeks apart. This is an off-label use and requires a prescription from an authorised prescriber.

Adolescents aged under 18 years who meet the criteria for being at high risk of mpox exposure (as listed in section 14.5.1) are highly recommended MPV vaccination, to be given with a prescription and consent.

Individuals who have either been diagnosed with laboratory-confirmed mpox prior to vaccination or after the first dose are not recommended vaccination or further doses. This is because mpox infection likely confers adequate immune protection or boosts immunity in those recently vaccinated. For those with immunocompromise and diagnosed with mpox after their first dose of MPV, a second dose of MPV can be considered based on clinical judgement.

Two doses of MPV are recommended, particularly for individuals with immunocompromise including well-controlled HIV infection, regardless of smallpox (vaccinia) vaccination history.

MPV is contraindicated for anyone with a severe systemic allergic reaction (anaphylaxis) to a previous dose or any component of the vaccine, including a history of anaphylaxis to chicken protein.

MPV is contraindicated for anyone who has been diagnosed with myocarditis or pericarditis following a previous dose of this vaccine.

Individuals with a history of severe allergy to any excipient or trace residual of the vaccine, including chicken or egg protein, benzonase, gentamicin and ciprofloxacin, can receive MPV following discussion with vaccinator to weigh the risk of severe allergy with the risk of mpox infection. In these cases, observe for 30 minutes following vaccination and give post-vaccine advice.

It is unknown whether MPV (Jynneos) is associated with an increased risk for myocarditis or pericarditis, however, there is a theoretical risk (see section 14.7.1). Those with previous myocarditis or pericarditis should have a risk-benefit discussion.

Subcutaneous, not intradermal, administration is preferred for individuals with a history of severe keloid scarring.

Although mild to moderate AEFI have occurred following vaccination with mpox, no serious adverse events have been reported to be causally associated with the vaccine. Adverse events were reported at similar rates for doses received by intradermal and subcutaneous administration.[30]

Active surveillance in Aotearoa New Zealand from the Post Vaccine Symptom Check (PVSC) of the MPV (Jynneos; mainly administered ID during the survey period from 26 January to June 2023) showed the rate of adverse events was similar or less than reported during clinical trials. Of the PVSC day-7 survey participants, 68 percent reported at least one adverse event, 4 percent reported missing work or other daily activities and less than 2 percent sought medical care. Local reactions and fatigue were most commonly reported (unpublished data, Health New Zealand).

Based the older replication-competent smallpox (vaccinia) vaccines, there is a theoretical risk of myocarditis and pericarditis with MPV. Clinical trials of MPV found no signal for myocarditis or pericarditis. Two cases were reported to the VAERS in the US after approximately 652,641 first doses and 334,568 second doses (incidence <3 per million doses).[30] As the incidence of these adverse events is very rare, it is important to remain vigilant for potential symptoms in young men following MPV vaccination.

Bavarian Nordics’ global safety database contained 9,585 AEFI from 3,363 individual case safety reports following approximately 1.7 million doses of MPV up to 31 July 2023 (1.2 million doses given in the US). The majority were general local and systemic inflammatory reactions. Many of the reports were either ‘incorrect route of product administration’ errors or immunisation-stress related responses following the change to ID injections. The passive reporting frequency of myocarditis (9 cases) or pericarditis (4 cases) was less than 1 per 100,000 doses.[31]

Clinical trials of MPV found that individuals with atopic dermatitis reported a higher frequency of adverse reactions than healthy individuals. Higher rates of injection site erythema and swelling, and slightly higher rates of systemic reactions were observed. Although around 7 percent experienced a flare-up or worsening of their skin condition during the clinical trials, this may have been in line with the underlying relapsing-remitting nature of the disease rather than in response to vaccination.[32]

Give one 0.5 mL dose of MPV subcutaneously, preferably within four days of exposure to mpox virus. Asymptomatic individuals can be offered vaccination up to 14 days after exposure with the aim of reducing severity of symptoms. A high-risk close contact can include:

• Direct physical contact with skin or mucous membranes of a case. (i.e., skin to skin, skin to mucous membranes, mucous membrane to mucous membrane).
• People whose occupation might put them at increased risk where there is a breach of protective personal equipment (PPE) (i.e., healthcare workers caring for those infected with mpox and laboratory workers handling mpox swabs).
• Direct contact with potentially contaminated materials (bed linens, healthcare equipment), crusts from lesions or with bodily fluids from a case.
• It also includes any household member who has had close physical contact with the mpox case or close contact with bedding, towels or clothing used by an individual with mpox.
• Those recommended to have the vaccine by their doctor.

If the individual remains mpox symptom-free for up to 4 weeks after exposure, give a second dose to provide longer lasting, particularly for those at risk of future exposures (ie would be considered the same as a pre-exposure vaccination).

1.        World Health Organization. Smallpox and mpox (orthopoxviruses) vaccine position paper. Weekly Epidemiological Record, 2024. 99(34): p. 429-456.

2.        Lapa D, Carletti F, Mazzotta V, et al. Monkeypox virus isolation from a semen sample collected in the early phase of infection in a patient with prolonged seminal viral shedding. Lancet Infectious Diseases, 2022. 22(9): p. 1267-1269.

3.        Peiro-Mestres A, Fuertes I, Camprubi-Ferrer D, et al. Frequent detection of monkeypox virus DNA in saliva, semen, and other clinical samples from 12 patients, Barcelona, Spain, May to June 2022. Euro Surveillance, 2022. 27(28).

4.        Mbala PK, Huggins JW, Riu-Rovira T, et al. Maternal and fetal outcomes among pregnant women with human monkeypox infection in the Democratic Republic of Congo. Journal of Infectious Diseases, 2017. 216(7): p. 824-828.

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9.        Stittelaar KJ, van Amerongen G, Kondova I, et al. Modified vaccinia virus Ankara protects macaques against respiratory challenge with monkeypox virus. Journal of Virology, 2005. 79(12): p. 7845-51.

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11.      Berry MT, Khan SR, Schlub TE, et al. Predicting vaccine effectiveness for mpox. Nat Commun, 2024. 15(1): p. 3856.

12.      Ghazy RM, Elrewany E, Gebreal A, et al. Systematic review on the efficacy, effectiveness, safety, and immunogenicity of monkeypox vaccine. Vaccines (Basel), 2023. 11(11).

13.      Overton ET, Lawrence SJ, Wagner E, et al. Immunogenicity and safety of three consecutive production lots of the non replicating smallpox vaccine MVA: A randomised, double blind, placebo controlled phase III trial. PloS One, 2018. 13(4): p. e0195897.

14.      Greenberg RN, Overton ET, Haas DW, et al. Safety, immunogenicity, and surrogate markers of clinical efficacy for modified vaccinia Ankara as a smallpox vaccine in HIV-infected subjects. Journal of Infectious Diseases, 2013. 207(5): p. 749-58.

15.      Oom AL, Kottkamp AC, Wilson KK, et al. 2024 (preprint). The durability and avidity of MPXV-specific antibodies induced by the two-dose MVA-BN mpox vaccine. DOI: 10.1101/2024.01.28.24301893 (accessed 19 September 2024)

16.      Greenberg RN, Hay CM, Stapleton JT, et al. A randomized, double-blind, placebo-controlled phase II trial investigating the safety and immunogenicity of Modified Vaccinia Ankara smallpox vaccine (MVA-BN®) in 56-80-year-old subjects. PloS One, 2016. 11(6): p. e0157335.

17.      Mazzotta V, Lepri AC, Matusali G, et al. Immunogenicity and reactogenicity of modified vaccinia Ankara pre-exposure vaccination against mpox according to previous smallpox vaccine exposure and HIV infection: prospective cohort study. EClinicalMedicine, 2024. 68: p. 102420.

18.      Pischel L, Martini BA, Yu N, et al. Vaccine effectiveness of 3rd generation mpox vaccines against mpox and disease severity: A systematic review and meta-analysis. Vaccine, 2024. 42(25): p. 126053.

19.      Dalton AF, Diallo AO, Chard AN, et al. Estimated effectiveness of JYNNEOS vaccine in preventing mpox: A multijurisdictional case-control study - United States, August 19, 2022-March 31, 2023. MMWR: Morbidity and Mortality Weekly Report, 2023. 72(20): p. 553-558.

20.      Golden MR, Soge OO, Mills M, et al. Asymptomatic and subclinical mpox: An association with Modified Vaccinia Ankara vaccine. Sexually Transmitted Diseases, 2024. 51(5): p. 342-347.

21.      Thy M, Peiffer-Smadja N, Mailhe M, et al. Breakthrough infections after postexposure vaccination against mpox. New England Journal of Medicine, 2022. 387(26): p. 2477-2479.

22.      Cornelisse VJ, Kearley JJM, Vargas Castillo J, et al. Case study: breakthrough mpox infection in Aotearoa New Zealand and Australia after completed two-dose course of subcutaneous modified vaccinia Ankara (MVA-BN) vaccines. Sex Health, 2023. 20(6): p. 585-587.

23.      Allard R, Leclerc P, Bergeron G,Cadieux G. Breakthrough cases of mpox: One-dose vaccination is associated with milder clinical manifestations. J Infect Public Health, 2024. 17(4): p. 676-680.

24.      Fontán-Vela M, Hernando V, Olmedo C, et al. Effectiveness of modified Vaccinia Ankara-Bavaria Nordic vaccination in a population at high risk of mpox: A Spanish cohort study. Clinical Infectious Diseases, 2024. 78(2): p. 476-483.

25.      Rosen JB, Arciuolo RJ, Pathela P, et al. JYNNEOS effectiveness as post-exposure prophylaxis against mpox: Challenges using real-world outbreak data. Vaccine, 2024. 42(3): p. 548-555.

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