Guidance on the use of mpox vaccines. Revised edition [EN/PT] – World – ReliefWeb

INTRODUCTION

Smallpox eradication was certified in 1980. Mpox has been endemic in Central and West African countries since it was first detected in 1958 (1). It is a zoonosis; cases are often found close to tropical rainforests where various animals carry the orthopoxvirus that causes the disease. In endemic countries, most mpox infections in humans result from a primary animal-to-human transmission. Human-to-human transmission can result from close contact with respiratory secretions, skin lesions of an infected person, or recently contaminated objects. Transmission can also occur via the placenta from mother to fetus or through close contact during and after birth. (2)

As of 21 May 2022, 12 non-endemic countries in two World Health Organization (WHO) regions had reported 92 confirmed cases of mpox. By 26 August 2022, 96 non-endemic countries in all six WHO regions had reported 45 198 confirmed cases of mpox, including 6 deaths. During the same period, endemic countries reported 350 confirmed cases and 6 deaths. In the Region of the Americas,(1) 29 countries and territories reported 23 479 confirmed cases (48%) and 3 deaths (2,3).

Several observational studies on first generation vaccines demonstrated that smallpox vaccination was around 85% effective in preventing mpox (4). At the present time, the original (first-generation) smallpox vaccines are no longer available.

A second-generation smallpox vaccine (ACAM2000) was subsequently developed, which has been used to immunize and protect personnel at high risk of occupational exposure, such as laboratory workers and those whose work in endemic areas (5, 6). A third-generation vaccine based on a modified attenuated vaccinia virus (Ankara strain) was approved for the prevention of mpox in 2019.

Smallpox and mpox vaccines are developed in formulations based on the vaccinia virus, which offer some crossprotection for the immune response to orthopoxviruses. However, the availability of vaccines is limited.

On 31 May 2022, the VIII Ad Hoc Meeting of the Technical Advisory Group (TAG) on Vaccine-Preventable Diseases of the Pan American Health Organization (PAHO) (8) was held to address the outbreak of mpox in several countries. The meetings recommendations were:

On 14 June 2022, the World Health Organization (WHO) published interim guidance on vaccines and vaccination against mpox with the advice and support of its Ad-hoc Working Group on Smallpox and Mpox Vaccines of the Strategic Advisory Group of Experts (SAGE) (9). This interim guidance includes:

On 23 July 2022, the WHO Director-General declared the mpox outbreak a public health emergency of international concern (PHEIC) (10). A coordinated response was launched, aimed at interrupting transmission and protecting vulnerable groups, and a number of recommendations were made, including vaccination.

These temporary recommendations apply to different groups of countries, based on their epidemiological situation, patterns of transmission, and capacities. These recommendations include different aspects such as: the implementation of a coordinated response, community engagement and protection, surveillance and public health measures, clinical management, and infection control, among others. WHO recommends use of the vaccine for countries that have imported cases of mpox in the population and/or human-to-human transmission of monkeypox virus, including in key population groups and communities at high risk of exposure.

The overall goal of the global response to mpox as a PHEIC, is to stop human-to-human transmission and minimize zoonotic transmission of the monkeypox virus wherever it occurs.

The use of vaccines can contribute to this response. However, vaccination should be considered a measure to complement primary public health interventions that include surveillance, early case detection, diagnosis and care, isolation and contact tracing and follow-up, and self-monitoring to reduce contacts.

This document aims to provide useful accessible, and understandable information about mpox vaccines in order to facilitate deployment of vaccination strategies in the context of the current epidemiological scenario and based on the recommendations of the VIII Ad Hoc Meeting of the PAHO Technical Advisory Group (TAG) on Vaccine-Preventable Diseases (8).

This guidance offers a conceptual framework for available vaccines, supporting immunization program managers at the national and subnational levels and vaccinators in technical operations for vaccine utilization.

To facilitate updates, this document is organized around the various components required for deployment and includes relevant information on vaccines, administration techniques, the information system, events supposedly attributable to vaccination or immunization (ESAVI; also known as adverse events following immunization [AEFI]), waste management, and indications for vaccination.

(1) Daily update of the regional epidemiological situation. Pan American Health Organization. Monkeypox cases Region of the Americas. Washington, DC: PAHO. Available from: https://shiny.pahobra.org/monkeypox/

REFERENCES (1) United States Centers for Disease Control and Prevention. About Monkeypox. Atlanta; CDC; 2022. Available from: https://www.cdc.gov/poxvirus/monkeypox/about.html (2) World Health Organization. Mpox (monkeypox). Geneva; WHO; 2022. Available from: https://www.who.int/healthtopics/monkeypox#tab=tab_1 (3) Pan American Health Organization. Weekly Situation Report on Monkeypox Multi-Country Outbreak Response - Region of the Americas. 26 August 2022. Available from: https://www.paho.org/en/documents/weekly-situationreport-monkeypox-multi-country-outbreak-response-region-americas-26 (4) Fine, P; Jezek, B; Grab, B; Dixon, H. The transmission potential of monkeypox virus in human populations. Int J Epidemiol. 1988 Sep;17(3):643-50. Available from: https://academic.oup.com/ije/article-abstract/17/3/643/729853 (5) Food and Drug Administration. ACAM2000 (Smallpox Vaccine) Questions and Answers. Silver Spring: FDA; 2022. Available from: https://www.fda.gov/vaccines-bloodbiologics/vaccines/acam2000-smallpox-vaccine-questions-andanswers (6) Food and Drug Administration. ACAM2000. Silver Spring: FDA; 2019. Available from: https://www.fda.gov/vaccinesblood-biologics/vaccines/acam2000 (8) Pan American Health Organization. VIII Ad Hoc Meeting of PAHOs Technical Advisory Group (TAG) on Vaccine-Preventable Diseases. Technical Briefing on the Multi-Country Monkeypox Outbreak: Recommendations onMonkeypox Vaccines and Vaccination. Washington, D.C.: PAHO; 2022. Available from: https://iris.paho.org/handle/10665.2/56102?locale-attribute=en (9) World Health Organization (WHO). Vaccines and immunization for monkeypox. Interim guidance, June 2022. Geneva: WHO; 2020. Available from: https://apps.who.int/iris/handle/10665/356120?search-result=true&query=Vvccines+and+immunization+for+monkeypox%3A+Interim+guidance%2C+14+June+2022&scope=&rpp=10&sort_by=score&order=desc (10) World Health Organization. WHO Director-Generals statement at the press conference following IHR Emergency Committee regarding the multi-country outbreak of monkeypox - 23 July 2022. Geneva: WHO; 2022. Available from: https://www.who.int/es/director-general/speeches/detail/who-director-general-s-statement-on-the-pressconference-following-IHR-emergency-committee-regarding-the-multi--country-outbreak-of-monkeypox--23-july2022

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Guidance on the use of mpox vaccines. Revised edition [EN/PT] - World - ReliefWeb