A new international study led by Queen Mary University of London has shown mpox (formerly known as monkeypox) infections to be less severe among those who are vaccinated or had a previous infection in 2022, underlining the importance and effectiveness of vaccination.
The research, published in The Lancet Infectious Diseases, was delivered by the SHARE-net collaborative and looked at 38 mpox infections in 37 gay and bisexual men. Eight of the 38 were reinfections, and 30 infections occurred after a complete vaccination course. In the people who had been vaccinated, the results showed that the patients had fewer lesions (abnormal tissue such as a wound or rash), less mucosal disease (diseases of the mucous membranes of the mouth and genitals), and a minimal need for pain medication or hospitalization.
The severity of symptoms was observed and assessed using the Mpox-SSS score, which was developed during the 2022 multi-country outbreak. The Mpox-SSS score is a numerical score given considering seven different factors including the number of lesions, the level of care required for the patient, the amount of pain medication needed, the extent of mucosal areas affected, and whether there is any bacterial superinfection – i.e., additional infections.
Using this scoring system it was possible to demonstrate and measure severity. In those who had been reinfected, the disease was less severe with a lesser requirement for pain medication compared to their first bout, and fewer areas of the body were affected while recovery was also faster. The first infection lasted 21 days (median) whereas the second infection lasted 15 days (median).
Neither natural immunity from a prior mpox infection nor post-vaccination immunity can prevent someone from getting the virus. However, the study shows that the immunity from both reduces severity.
