Authors: Dr Laura Waters, Dr Mary Ramsay, Prof Marta Boffito, Dr Claire Dewsnap, Dr Jonathan Underwood, Dr Clare van Halsema and Prof Anna Maria Geretti
Publication date: 13 October 2022
Review date: 13 October 2023
As of 26 September 2022, 3,485 confirmed cases of monkeypox virus (MPV) infection have been reported in the UK, 95% in England with 69% of cases in England occurring in London residents. Gay and bisexual men who have sex with men (GBMSM) continue to be impacted disproportionately.
The UK Health Security Agency (UKHSA) epidemiological overview can be found here:
Latest information on case definitions, vaccination and principles of infection control can be found here:
Prior to the current outbreak the evidence as to how HIV impacts risk of MPV acquisition or its disease course was limited to two case series from Nigeria:
118 MPV cases: 6% mortality rate; 4/7 deaths in people with HIV, at least three with advanced HIV and not on antiretroviral therapy (ART); total number with HIV not described .
40 MPV cases (nine with HIV; at least seven with high viraemia and/or low CD4 counts): people with HIV experienced more prolonged illness, larger lesions and higher rates of both secondary bacterial skin infections and genital ulcers .
Another case series from the USA included 34 MPV cases, but HIV status was not reported; there were no deaths .
Since then, several large case series have been published, including:
528 cases from 16 countries across five continents: 98% GBMSM and 41% with HIV (96% on ART, 95% virally suppressed, median CD4 count 680 cells/mm3). Clinical presentation was similar among those with and without HIV, including frequency of hospital admission. Three people experienced serious complications: one case of epiglottitis in a person with HIV; two cases of myocarditis, one in a person living with HIV .
181 cases from Spain: 92% GBMSM, 40% with HIV (11% with CD4 counts <500 cells/mm3), HIV status did not impact incubation period, clinical features, or lesion number. Median time from lesion onset to dry crusting was 11 days (interquartile range [IQR] 8–14 days) for people with HIV versus 10 days (IQR 7–12 days) for people without HIV .
197 cases from London, 196 GBMSM, 36% with HIV (median CD4 664 cells/mm3) of whom 79% were known to be virally suppressed. Of 20 people requiring hospital admission, 15 (75%) were people living with HIV of whom 3 (15%) were considered immunosuppressed .
Among 21,098 cases reported through the European Surveillance System between March and August 2022 (99% males, mostly GBMSM), people living with HIV accounted for 37% of cases where HIV status was known (3070/8257); their hospitalisation rate was similar to that of 8257 people without HIV (12/1000 cases vs. 10/1000; p=0.441) .
As of 27 September 2022, there have been 13 reported MPV-related deaths globally, with an overall mortality of 0.01% (0.6% and 0.01% in countries that have and have not reported MPV historically, respectively) . Whether mortality in the 2022 outbreak is associated with immunosuppression, including HIV, remains unknown but has not been described to date.
Beyond vaccine considerations, we do not recommend any specific actions for people living with HIV beyond vigilance about clinical presentations and risk. We suggest the following groups may be at higher risk of MPV complications, so should be prioritised for specialist review. People with:
CD4 count <200 cells/mm3
Recent HIV-related illness (e.g. AIDS diagnosis in the previous 6 months)
Persistent HIV viraemia (including at low level, e.g. >200 copies/mL)
Concomitant conditions or treatments that may cause immune suppression.
Based on the data outlined and experience with other vaccines, we recommend:
People with HIV can be offered a non-replicating smallpox vaccine
The immune response with a CD4 cell count <100 cells/mm3 has not been evaluated but no impact of HIV on safety is anticipated
Most people with HIV can be advised that they can expect good immune responses to smallpox vaccination
Although slightly lower antibody responses are seen in people with HIV after the first dose, the difference vs. HIV-negative people is less after the full vaccine course; maximal responses are expected to require around two weeks after the second dose.
Animal models and evidence emerging from the current epidemic suggest that protection from a single vaccine dose is high (~80%) and conferred quite early, but there is very limited evidence to confirm that this is also the case in those with HIV.
All immunosuppressed people with HIV should receive two subcutaneous ‘full dose’ vaccines
People with a CD4 count <200 cells/mm3 or persistent viraemia (including at low level)
People with immunosuppression related to another condition or treatment in line with the Green Book
People with a CD4 count >200 cells/mm3 and viral suppression can receive intradermal fractionated vaccine doses
Route and dose of administration is considered interchangeable
People with detectable viraemia should be supported to achieve viral suppression to maximise vaccine efficacy
There are two smallpox vaccines that also confer protection against MPV:
One prepared with live vaccinia virus, which is no longer available in the UK
An attenuated non-replicating vaccine, e.g. the MVA-BN (Imvanex) vaccine recommended by UKHSA .
Non-replicating smallpox vaccines can be used in line with existing BHIVA vaccine guidance . The MVA-BN vaccine has been studied in people living with HIV and a CD4 count >100 cells/mm3. The vaccine can be used at CD4 counts <100 cells/mm3 although is likely to be less effective (particularly if the CD4 count is <50 cells/mm3); patients with low CD4 counts should receive specialist advice about protection from exposure.
A single dose of MVA-BN is recommended as post-exposure prophylaxis within 4 days of exposure for all. It should be considered up to 14 days post-exposure (for those not displaying symptoms) in those at higher risk of serious MPV infection. Although the Green Book defines all people living with HIV as immunosuppressed for vaccine purposes, regardless of CD4 count  it specifically considers only those with a CD4 cell count <200 cells/mm3 or detectable viral load as immunosuppressed for the purposes of vaccination against MPV .
i-base has summarised the serological response rates to MVA-BN vaccines in people with and without HIV . Key points from these studies are:
In a study of 151 people (91 with HIV, 97% on ART, CD4 ≥350 cells/mm3), MVA-BN vaccination was equally safe and well tolerated and yielded similar total and neutralising antibody kinetics, regardless of HIV status .
Vaccinia-naïve population, two vaccine doses 4 weeks apart: total/neutralising antibody seroconversion rates in people with HIV versus people without HIV were 83%/89% versus 78%/96% 2 weeks after one dose and 92%/91% versus 96%/93% 2 weeks after the second dose.
Though seroconversion rates were similar, antibody titres tended to be lower in people with HIV.
Vaccinia-experienced population (previously vaccinated against smallpox), one vaccine dose: 74–89% had low-level antibodies prior to vaccination, irrespective of HIV status. Antibody responses were boosted by the vaccine, with total and neutralising antibodies in ≥90%, regardless of HIV status.
In a study of 579 people (482 with HIV, median CD4 count 420 [range 200–750] cells/mm3) receiving at least one vaccine dose, total antibody seroconversion rates were high and similar regardless of HIV status . Total antibody detection in people with HIV versus people without HIV:
Vaccinia-naïve, 4 weeks after first dose: 80% versus 86%
Vaccinia-naïve, 2 weeks after second dose: 98% versus 100%
Vaccinia experienced, 4 weeks after first dose: 93% versus 100%
Vaccinia-experienced, 2 weeks after second dose: 99% versus 100%.
Although HIV status and baseline CD4 count had no impact on seropositivity rates, among vaccinia-naïve participants, antibody titres were significantly higher in HIV-negative people than in those with HIV at 2 and 4 weeks post-second vaccine dose; there was a trend towards lower titres with lower CD4 counts (data not included). There were no differences in antibody titres in vaccinia-experienced people by HIV status.
In one trial, 91% of people receiving MVA-BN developed neutralising antibodies by day 14 after a single vaccine dose; this study did not include people with HIV .
Although the human immunological data is helpful, data from animal challenge studies suggests that protection after a single dose vaccine is conferred within a few days [17,18]. Recent evidence from Israel  suggests that protection from a single dose of vaccine is of the order of 79%. Although the latter study included people living with HIV, the number of cases was too small to provide specific evidence for this population. The observation of protection is supported by a lower rate of cases in those who have received a single dose of vaccine, compared to unvaccinated people in the USA; this latter data is not stratified by HIV status .
There are three antivirals available to treat MPV:
1. Tecovirimat: potential for drug–drug interactions (DDIs), see Liverpool website 
2. Brincidofovir (oral pro-drug of cidofovir): potential for DDIs, see Liverpool website 
3. Cidofovir high nephrotoxic potential; avoid nephrotoxic antiretrovirals (e.g. tenofovir disoproxil) and lack of data with tenofovir alafenamide warrants caution.
There are no guidelines for routine antivirals to treat MPV. Inpatient decisions should be made on a case-by-case basis. We encourage recruitment of people with MPV not requiring hospitalisation to relevant clinical trials.
BASHH provides several monkeypox resources, including management of proctitis, on their website (https://bashh.org/news/monkeypox-resources/).
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