Estimated vaccine effectiveness (VE) of a single dose of the Jynneos attenuated smallpox/mpox vaccine against symptomatic mpox infection was 78% at least 14 days later, according to a study published yesterday in The Lancet Infectious Diseases.

Researchers at the UK Health Security Agency sent questionnaires to men who have sex with men (MSM) in England diagnosed as having mpox from July 4 to October 9, 2022, and linked the answers to lab data and a public health case-management system.

The team calculated VE by comparing vaccine coverage among eligible patients from the number of estimated doses given to at-risk MSM and the estimated size of that population.

2.2% breakthrough infection rate

By October, 47% of 363 mpox patients had received one dose of the Jynneos vaccine. Eight respondents (2.2%) had breakthrough infections at least 14 days after vaccination, 32 (8.8%) were diagnosed within 13 days after vaccination, and 323 (89.0%) were unvaccinated.

Estimated one-dose VE against symptomatic mpox was 78% after at least 14 days (95% confidence [CI], 54% to 89%), ranging from 71% to 85% in sensitivity analyses. VE was –4% in the first 13 days after vaccination (95% CI, –50% to 29%).

"A single MVA-BN [Jynneos] dose was highly protective against symptomatic mpox disease among at-risk [MSM], making it a useful tool for mpox outbreak control when rapid protection is needed," the authors wrote. "For cases in which numbers at highest risk of infection exceed vaccine supply, there might be benefit in prioritising delivery of first doses."

There might be benefit in prioritising delivery of first doses.

In a related commentary, Dimie Ogina, MBBS, of Niger Delta University in Nigeria, and Nathalie Strub-Wourgaft, MD, of the Drugs for Neglected Diseases Initiative in Switzerland, noted that half of the breakthrough mpox infections occurred in HIV patients.

"However, the MVA-BN vaccines have previously been shown to be immunogenic among adults with a history of AIDS, and larger cohorts of people living with HIV will be required to ascertain if HIV is a risk factor for MVA-BN vaccine failure," they wrote.

The European Centre for Disease Prevention and Control (ECDC) reported today that 67 cases of botulism linked to a weight loss procedure have been reported in Turkey and three other European countries.

The 67 cases of the neuroparalytic illness have all been linked to intragastric injection of the botulism neurotoxin (BoNT), with 53 cases reported in Turkey, 12 in Germany, and 1 each in Austria and Switzerland. The patients had the procedure from February 22 to March 1, and among the 63 patients with information, 60 were treated at a private hospital in Istanbul and 3 at a hospital in Izmir. The relevant departments of both hospitals have had their activities suspended.

Symptoms range from mild to severe, with several of the patients hospitalized and a number reportedly admitted to intensive care units and treated with botulinum anti-toxin.

BoNT products, such as Botox, are derived from the bacterium Clostridium botulinum and are commonly used for cosmetic purposes. The ECDC said investigation by Turkish authorities found that licensed BoNT products were used in the procedures, but that these products are not approved for the treatment of obesity by intragastric injection. Excessive doses of BoNTs can cause botulism.

The ECDC is warning European Union/European Economic Area citizens to avoid intragastric treatments with BoNT for obesity in Turkey.

Brazil's drug regulatory agency has approved Japan-based Takeda's four-strain vaccine against dengue virus for use in people ages 4 to 60 years old, the company announced yesterday.

Takeda's vaccine can be used regardless of earlier dengue infection and doesn't require testing for prior infection before use. Brazil is the first country in Latin America to approve the vaccine, called Qdenga, to combat the mosquito-borne disease.

The company's vaccine is a live attenuated product built on a serotype 2 backbone and includes all four dengue serotypes. It is given subcutaneously in two doses, 3 months apart.

Brazilian officials based their approval on clinical studies that included more than 28,000 children and adults. Efficacy varied by dengue serotype, and over the 4.5-year study period, the vaccine prevented 84% of hospitalized cases and 61% of symptomatic cases.

Vivian Kiran Lee, MD, Takeda's medical affairs director in Brazil, said dengue outbreaks and hospitalizations strain Brazil's health system. In 2022, the country saw a huge spike in activity, resulting in more than 1.4 million cases and more than 1,000 deaths. She said the company's vaccine reduces barriers to vaccination and has the potential, when combined with vector control programs, to reduce the burden of the disease on health systems.