More Mpox Vaccine Breakthrough Cases Confirmed

While the global outbreak of Mpox has steadily declined, recent reports indicate a resurgence of local and vaccine breakthrough cases.

For example, Public Health France reported 17 confirmed Mpox cases in the Centre-Val de Loire region in April 2023.

An investigation showed six of these cases received no smallpox vaccination, one reported having a non-complete vaccination schedule with a 1st generation smallpox vaccine, such as ACA2000, and ten reported complete vaccinations: five with a 1st generation smallpox vaccine in childhood plus one dose of 3rd generation vaccine in 2022, and five with two doses of 3rd generation vaccine in 2022.

This data indicates 59% were vaccine breakthrough cases in this cluster in southwest Paris.

And is significantly greater than what has been observed at France's national level (25%) between October and February 2023 in France concerning vaccinated men.

In summary, Public Health France says there is a minimal perspective on the efficacy of 3rd generation vaccines against Mpox infection. 

And there are no data on long-term protection after a full vaccination course, nor in population subgroups. 

Moreover, to date, no signal has been issued on the quality or safety of these vaccines. 

As of April 9, 2023, this episode suggests that the localized Mpox transmission in the Touraine sector indicates at-risk contacts and exposures in other regions, particularly in Ile-de-France.

In other mpox developments, the European Centre for Disease Prevention and Control (ECDC) and the World Health Organization (WHO) European regional office posted a joint update on April 5, 2023, which reported 28 new Mpox cases from 7 countries over the past month.

Six were from Spain, with Mpox cases in Portugal, the Netherlands, Switzerland, Greece, and Malta.

In the United States (U.S.), communities can monitor the presence of the Mpox virus in wastewater samples. This data offers an early warning of local mpox activity.

The U.S. Centers for Disease Control and Prevention (CDC) began offering Bavarian Nordic's Jynneos® vaccine on May 24, 2022. Since then, over 1.2 million vaccine doses have been administered as of April 4, 2023.

The CDC recently updated the U.S. National Mpox Vaccination Strategy on February 6, 2023, and recommends that people exposed to the Mpox virus and those more likely to contract Mpox should be vaccinated. 

Unfortunately, it's unknown whether Jynneos's protection might decrease over time, says the CDC.

The good news is next generation Mpox vaccine candidates are conducting clinical studies.

Article Updated on April 28, 2023, with corrected citation link.