Low-level mpox transmission continues in many parts of the world, with Africa, Europe, and the Americas reporting the largest portion of recent cases, the World Health Organization (WHO) said in a monthly situation update yesterday, which covers cases reported in March.

Adding a caveat that a decline in surveillance may underestimate infections, the WHO said 466 new cases, 3 of them fatal, were reported in March. In Africa, the Democratic Republic of the Congo (DRC)—experiencing an outbreak of a novel clade 1 virus—reported the most cases.

Ten countries reported case rises in March, with the Republic of Congo reporting the largest rise in Africa. Other hot spots were the United Kingdom, Puerto Rico in the United States, and Vietnam.

The WHO said the risk is high for the DRC's general population and moderate for countries that have historically reported mpox infections and for men who have sex with men, gender-diverse people, and sex workers. The general population risk for countries that haven't experienced earlier outbreaks is low.

Over the past 6 months, monthly cases have fluctuated between 400 and 1,000 cases, with most reported in the Americas, Europe, and Africa. Though sexual encounters are the most common mode of transmission, patterns in Africa are more diverse and include the zoonotic route.

Advisers discuss mpox vaccine issues

WHO vaccine advisers met in March, and they said populations to consider for vaccination include adults and children in geographic areas with documented exposure risks, people with multiple sexual contacts, health workers with repeated exposure, and known contacts of infected people. 

The group called for strong measures to promote mpox and vaccine research in Africa, along with equitable access to vaccines. The committee expects to release its final recommendations on mpox  immunization in May.

A new meta-analysis of 16 studies reveals that, for pre-exposure prophylactic vaccination (PrEP, which is used for disease prevention), the vaccine effectiveness (VE) of one Jynneos dose ranged from 35% to 86%, and VE for  post-exposure prophylactic vaccination ranged from 78% and 89% for one dose.

The findings are published on the preprint server medRxiv and represent the most current evidence of vaccine protection offered by Jynneos, Bavarian Nordic's two-dose vaccine used for the past 2 years to fight a global mpox outbreak. The study has not yet been peer-reviewed.

As of February 2024, more than 94,000 confirmed mpox cases have been documented in 117 countries in an outbreak that mostly affected men who have sex with men. Jynneos, also called MVA-BN, can be administered prophylactically either before or after exposure to confirmed mpox cases in two doses, administered 28 days apart.

The analysis included data from six countries: the United States, Canada, Spain, the United Kingdom, Israel, and the Netherlands.

Different administration routes protective

In eight studies, the VE of one dose of MVA-BN administered as PrEP was 35% to 86%, while five studies reported two-dose adjusted VE estimates ranging from 66% to 90%.

Two studies also provided VE estimates for administering Jynneos with intradermal injection or subcutaneously, and found similar ranges of protection regardless of administration route: 80% (95% confidence interval [CI], 23% to 95%) for intradermal administration, 89% (95% CI, 56% to 97%) for subcutaneous administration, and 87% (95% CI, 69% to 95%) when administered via a combination.

The authors conclude that the findings "demonstrated the effectiveness of one or two doses of MVA-BN against symptomatic mpox infection in outbreak settings."

A laboratory- and population-based surveillance study conducted in nine states found a low incidence of carbapenem-resistant Acinetobacter baumannii (CRAB) infections, but most isolates carried a carbapenemase gene and had limited treatment options, researchers reported this week in the American Journal of Infection Control.

Using data collected through the Emerging Infections Program's Multi-site Gram-negative Surveillance Initiative (MuGSI) from January 1 through December 31, 2019, researchers from the Centers for Disease Control and Prevention analyzed 136 CRAB cases in 125 patients. The crude incidence rate was 0.70 cases per 100,000 population.

Of the 66 CRAB isolates submitted for further analysis, 37 (56.1%) were from men, 36 (54.6%) were from Black or African American patients, 50% were collected from outpatient settings, and the median age of patients was 63.5 years. Whole-genome sequencing found that 48 isolates (72.7%) harbored an acquired carbapenemase gene, mainly bla_OXA-23 or bla_OXA-24/40. One isolate harbored bla_NDM. The isolates were resistant to many first-line antibiotics used to treat CRAB infections, with 50 (75.8%) defined as difficult to treat (DTR). Of the 11 case-patients who died, 9 had isolates that met the DTR definition.

Cefiderocol, which was approved by the Food and Drug Administration in 2019, had the most in vitro activity against the CRAB isolates among the 19 antibiotics tested.

Defining the landscape of CRAB

The study authors say the detailed clinical and microbiologic data allow for a deeper understanding of the epidemiology of CRAB across the spectrum of healthcare.

"This surveillance activity has demonstrated its value in helping to define the landscape of CRAB by providing a unique view of the molecular epidemiology of CRAB in the U.S., reinforcing the importance of tracking emerging and potentially transmissible resistance in A. baumannii complex to help inform and evaluate infection prevention and control strategies," they wrote.