Mpox Crisis in Africa: The Emergence of Clade 1b and the Race for Effective Vaccination

In a recent news article for Nature, Sara Reardon discussed the spread of Monkeypox in Africa and examined how vaccines might help improve the situation (https://www.nature.com/articles/d41586-024-02793-9). Here’s a brief summary of her piece.

The WHO declared a public health emergency due to the new Mpox variant, clade 1b, spreading in previously unaffected African countries. Unlike clade Ia, which primarly spread via wild animals, clade 1b primarily spreads through human contact, including sexual activity. This shift in transmission has caused nearly 18,000 infections and over 600 deaths, many among children, in the Democratic Republic of the Congo this year.

The current outbreak of clade 1b raises critical questions about its transmissibility and severity compared to other variants, such as clade II, which caused a global outbreak in 2022. Researchers suggest that clade 1b may be more transmissible due to genetic mutations that have accumulated from prolonged circulation in humans. These mutations indicate that the virus may have adapted to human hosts, enhancing its ability to spread. However, experts emphasize that factors like population density and the specific characteristics of the affected regions play a crucial role in the virus’s spread.

Determining the fatality rate of clade 1b is complex. While some reports suggest a high mortality rate for clade I infections, there is skepticism about these figures due to potential underreporting and misclassification of cases. Secondary health conditions like untreated HIV and malnutrition, especially in children and the immunocompromised, complicate assessing the virus’s lethality.

Vaccination remains a vital tool in combating the outbreak. However, the effectiveness of existing vaccines, such as Jynneos and LC16m8, which were developed for smallpox, against clade I variants is not well understood. These vaccines have shown some efficacy in non-African populations against clade II, but their impact on clade I variants remains uncertain. In Africa, vaccine distribution has been hampered by delays in WHO approval and logistical challenges, leaving the continent with limited access to necessary doses. The slow response to providing vaccines and other resources has been criticized, as earlier intervention might have curtailed the outbreak’s spread. With many countries now pledging vaccine donations, there is hope that the situation will improve, but significant challenges remain in controlling the outbreak and protecting vulnerable populations.