Acceptance and timeliness of post-exposure vaccination against mpox in high-risk contacts, Amsterdam, the Netherlands, May-July 2022

C E van Ewijk; C Smit; R Bavalia; K Ainslie; A Vollaard; G van Rijckevorsel; S J M Hahné

doi:10.1016/j.vaccine.2023.10.013

Acceptance and timeliness of post-exposure vaccination against mpox in high-risk contacts, Amsterdam, the Netherlands, May-July 2022

Vaccine. 2023 Nov 13;41(47):6952-6959. doi: 10.1016/j.vaccine.2023.10.013. Epub 2023 Oct 12.

Authors

C E van Ewijk¹, C Smit², R Bavalia², K Ainslie³, A Vollaard⁴, G van Rijckevorsel⁵, S J M Hahné⁴

Affiliations

¹ Centre for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands; European Programme for Intervention Epidemiology Training (EPIET), European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden. Electronic address: katja.van.ewijk@rivm.nl.
² Department of Infectious Diseases, Public Health Service of Amsterdam, The Netherlands.
³ Centre for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands; School of Public Health, University of Hong Kong, Hong Kong Special Administrative Region, China.
⁴ Centre for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
⁵ Centre for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands; Department of Infectious Diseases, Public Health Service of Amsterdam, The Netherlands.

PMID: 37838481
DOI: 10.1016/j.vaccine.2023.10.013

Abstract

Background: May 2022, several countries reported mpox outbreaks among men-who-have-sex-with-men. In the Netherlands, high-risk contacts were offered the third-generation smallpox vaccine as post-exposure-prophylaxis (PEP) within 4 but maximum 14 days after exposure. We investigated their PEP acceptance, timeliness of uptake and development of mpox for the region of the Public Health Service (PHS) Amsterdam.

Methods: High-risk contacts identified during 20 May-22 July 2022 were included. Contacts were followed-up 21 days after exposure and classified as: no patient (no mpox symptoms or orthopoxvirus PCR-negative) or mpox patient (clinically suspected mpox or orthopoxvirus PCR-positive). We calculated time intervals between date of last exposure and first PHS consultation, PEP administration, and symptom onset.

Results: Two-hundred-ninety contacts were at high-risk of mpox predominantly due to sexual and/or direct skin-skin contact (212/290, 73 %). First PHS consultation was a median of 5 (IQR 3, 7) days after exposure, at which point 26/290 (9 %) contacts were ineligible for PEP. 84 % (223/264) of contacts eligible for PEP, received PEP within a median of 6 (IQR 3, 8) days after exposure. Of 282 contacts (missing outcome n = 8) 38 (14 %) developed mpox a median of 7 (IQR 5, 12) days after exposure, of whom 50 % (19/38) developed mpox before their first PHS consultation. Among contacts eligible for PEP, 2/38 (5 %) unvaccinated and 16/218 (7 %) vaccinated contact developed mpox.

Conclusions: PEP acceptance among contacts of mpox patients was high. However, PEP timeliness was inadequate. Half of contacts received PEP 6 or more days after exposure, and half of contacts who developed mpox had an onset prior to their first PHS consultation. Estimating PEP vaccine effectiveness is problematic due to the timeliness of PEP and the time it takes to generate vaccine-induced immunity. It is important to assess how PEP timeliness may improve and to promote pre-exposure vaccination to control mpox outbreaks.

Keywords: Evaluation; Mpox; Prevention measure; Third-generation smallpox vaccine; Vaccination programme.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Homosexuality, Male
Humans
Male
Mpox (monkeypox)*
Netherlands / epidemiology
Sexual and Gender Minorities*
Vaccination