The French ANRS DOXYVAC study, initiated in 2021, aims to assess the effectiveness of certain therapeutic interventions in preventing sexually transmitted infections (STIs) in men who have sex with men (MSM).
When the first cases of mpox (monkey pox) appeared in France, the scope of this study was expanded to assess the efficacy of the vaccine. Modified Vaccinia Ankara (MVA-BN or Imvanex®) against this virus.
A high level of protection
Since its launch, the ANRS DOXYVAC trial has included 502 MSM volunteers, living in the Paris region, using pre-exposure prophylaxis (PrEP) to prevent HIV infection and being at high risk of STIs (at least one STI during the year preceding inclusion).
Among these 502 participants, the researchers analyzed information from 472 people with data available before and after May 8, 2022, i.e. before and after the mpox epidemic period. These participants had reported having a median of ten partners in the previous three months and 20% had received a smallpox vaccine during childhood.
The characteristics of the 77 volunteers who contracted the mpox virus were compared with those of the “control” volunteers who did not have the virus. It was thus found that the cases of mpox affected younger people (37 years versus 40 years), who had had more sexual partners in the previous three months (7 versus 5) and who had been vaccinated against smallpox less during childhood (4% versus 23%).
The incidence of infection with the mpox virus was 67.4 per 1,000 person-months between May 9 and July 10, 2022. It then increased to 24.4 per 1,000 person-months between July 11 ( date from which it was possible to be vaccinated) and September 20. The researchers found that vaccination against the mpox virus alone in 2022 was associated with a reduced risk of developing the disease with 99% effectiveness.
We can be delighted with this high level of protection provided by the vaccine, but as Vincent Leclercq, CEO of Coalition PLUS, deplores “ access to vaccines and medicines is too often restricted to the richest countries. The mpox epidemic has shown it to us: only the countries of the North have been able to set up vaccination campaigns ».
Previously, ANRS DOXYVAC had already demonstrated the efficacy of a vaccine against meningococcal B (Bexsero®) in reducing the risk of gonococcal infection and that of the antibiotic doxycycline as a preventive treatment against sexually transmitted infections, when taken within 72 hours of sexual intercourse (see Univadis article: “Combining the vaccine Bexsero® and post-exposure antibiotic prophylaxis to reduce transmission of STIs? “).