Recent mpox transmissions in Europe of clade 1b in gay men: New ECDC assessment brief

24 October 2025. Related: Early access, mpox.

Simon Collins, HIV i-Base

On 24 October 2025, the European Centre for Disease Prevention and Control (ECDC) issued a press release and a new threat assessment on mpox based on a small number of recent cases of local transmission of clade 1b. [1]

This involves gay and bisexual men in Spain, the Netherlands, Italy and Portugal and are distinct from the previously reported cases linked to travel outside the EU.

The brief cautions that transmission may now be ongoing in sexual networks in European countries and that easy access to testing and vaccination for gay and bisexual men should be part of the public health response.

The 12-page threat report includes full details on these cases together with latest transmission data in the EU. [2]

Modelling predictions for the risk of further transmissions include projections based on numbers of non-steady partners.

comment

The briefing increases mpox to a moderate risk for gay and bisexual men at risk of mpox recommending the importance of vaccination. It also notes that these few cases are likely an underestimate. The highest risk will be in people living with HIV with a low CD4 count, especially if they are undiagnosed or not on ART.

The mpox vaccine is very effective at reducing serious symptoms but protection in people living with HIV depends on receiving both injections. These should now be routinely available as part of any sexual health checks at sexual health clinics in the UK.

NHS clinics will give priority to people who haven’t received a first injection or never received a second injection. People who are HIV negative might initially be limited to a single injection.

However, several studies have suggested that people living with HIV might benefit from a third booster dose two years after their last (second) dose. [3]

References

1. ECDC. Local transmission of clade 1b mpox cases detected in EU/EEA ECDC urges renewed vigilance. (24 October 2025).
   https://www.ecdc.europa.eu/en/news-events/local-transmission-clade-1b-mpox-cases-detected-eueea-ecdc-urges-renewed-vigilance
2. ECDC. Threat Assessment Brief: Detection of autochthonous transmission of monkeypox virus clade Ib in the EU/EEA. (24 October 2025).
   https://www.ecdc.europa.eu/en/publications-data/threat-assessment-brief-detection-autochthonous-transmission-monkeypox-virus  (website)
   https://www.ecdc.europa.eu/sites/default/files/documents/mpox-TAB-October-2025.pdf (12-page PDF report)
3. People living with HIV need two shots of the mpox vaccine and likely a booster after two years. HTB (April 2025).
   https://i-base.info/htb/50751