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Monkeypox: Single dose of smallpox vaccine offers 78% protection, UKHSA reports

BMJ 2022; 379 doi: https://doi.org/10.1136/bmj.o2829 (Published 23 November 2022) Cite this as: BMJ 2022;379:o2829
  1. Elisabeth Mahase
  1. The BMJ

A single dose of the MVA-BN (modified vaccinia Ankara-Bavarian Nordic) smallpox vaccine provides around 78% protection against monkeypox 14 days after vaccination, the UK Health Security Agency (UKHSA) has said.1

The agency’s analysis, released as a preprint, looked at monkeypox cases in England and vaccination uptake data from 4 July to 3 November 2022 in the eligible gay, bisexual, and men who have sex with men (GBMSM) cohort.

Of 363 cases in this period, eight people had been vaccinated at least 14 days before, and 32 had been vaccinated 0-13 days before. The remaining 323 had not been vaccinated during this outbreak, giving an estimated vaccine effectiveness of 78%.

The agency said that this was the “strongest UK evidence yet for the effectiveness of the vaccine,” which is sold as Imvanex in the UK and EU and as Jynneos in the US. Currently, the UK is providing a single dose of the vaccine to the GBMSM cohort, as well as to healthcare workers caring for patients with monkeypox and people who have already had close contact with someone with monkeypox.2

Steve Russell, NHS national director of vaccinations and screening, said, “More than 55 000 doses of the monkeypox vaccine have been delivered so far. While the risk of monkeypox remains low, we urge anyone eligible to come forward to get their vaccination.”

Since the outbreak began in May 2022 the UK has reported 3720 monkeypox cases up to 21 November.3 Vaccine uptake among eligible GBMSM increased steadily from July, reaching 47% by 9 October.

Jamie Lopez-Bernal, consultant epidemiologist at the UKHSA, said, “While monkeypox cases are low it remains vital to stay alert to the risks. We now know that a single vaccine dose provides strong protection against monkeypox, which shows just how important vaccination is to protect yourself and others. A second dose is expected to offer even greater and longer lasting protection.”

The UKHSA has said that it will continue to investigate the duration of protection from a single dose and two doses of the vaccine.

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