Monkeypox Outbreak: Weekly Update (September 5, 2022)

The US reported the first death of a person with monkeypox, but it is unclear what role the disease played in the patient's death. A small study suggests that the JYNNEOS vaccine yields a relatively low level of antibodies neutralizing the monkeypox virus.

As of September 2, there were 19,962 confirmed monkeypox cases in the US. The Centers for Disease Control and Prevention (CDC) Technical report shows that men remain the most affected group, as they account for 97.6% of cases where gender or sex data are available.

Of cases with race and ethnicity data, one-third — 33.1% — are Non-Hispanic White, 31.1% are Hispanic of any race, 31.1% are non-Hispanic Black, and 3.7% are non-Hispanic Asian.

The CDC data reveals that of cases with symptom data available, 97.8% reported rash. The other common symptoms are feeling unwell, fever, chills, headaches, swelling of lymph nodes, muscle pain, and itching of the skin.

Death of a patient with monkeypox

The Texas Department of State Health Services (DSHS) confirmed the first US death of a person with monkeypox last week. Health officials said the case is under investigation to determine what role monkeypox played in the death. According to the DSHS, a patient, who was an adult resident of Harris County, was severely immunocompromised.

There are two major strains — or clades — of the monkeypox virus. The one circulating in the US is Clade II, which has a mortality rate of around one in 100. Clade I is more severe, with a death rate of around one in 10.

The Centers for Disease Control and Prevention (CDC) data shows that 15 deaths of monkeypox were reported globally in 2022, including six in non-endemic countries.

At least 31 children tested positive

At least 31 children in the US have tested positive for monkeypox, ABC News reported last week. So far, 11 states and jurisdictions in the US have identified pediatric monkeypox cases. Texas alone has reported nine cases, while Florida has detected monkeypox cases in two children under the age of 4.

According to the CDC technical report released on September 1, investigations were initiated for 45 probable pediatric monkeypox cases. There were 21 cases aged 13-17 years, of which three were confirmed. Of 24 cases aged 12 years or younger, four were confirmed.

The CDC says that while data about monkeypox in children are limited, there is evidence from patients infected with Clade I of the monkeypox virus that the disease is more likely to be severe in children under eight years of age. In addition, individuals with immunocompromising conditions or certain skin conditions, such as eczema, are at risk of severe monkeypox disease.

"Relatively low" level of antibodies

A recent study by researchers at Erasmus University Medical Center in the Netherlands suggests that the JYNNEOS vaccine against monkeypox yields a relatively low level of virus-neutralizing antibodies in healthy individuals.

The study, which has not been peer-reviewed yet, included 35 individuals, 19 of whom were PCR-positive for monkeypox and 16 of whom were negative. Of these, the majority were born in 1974 or earlier and thus had been vaccinated against smallpox, which is in the same virus family as monkeypox.

The researchers compared virus-neutralizing antibodies between the various groups in the study. The smallpox vaccine is highly immunogenic but has severe side effects, which is why the vaccination program was discontinued following eradication.

The US Food and Drug Administration (FDA) approved the JYNNEOS vaccine, a weakened version of the smallpox vaccine, in 2019 to prevent smallpox and monkeypox disease in individuals 18 and older. Thus far, only animal testing has been conducted, but observational data on vaccine effectiveness is being collected as part of the monkeypox outbreak response.

Researchers say the study raises the question of how well vaccinated individuals are protected because "the role of monkeypox virus neutralizing antibodies for protection against disease and transmissibility is currently unclear and no correlation of protection against the infection has been identified."

According to the study, a dose-sparing approach — when a dose is split into five and injected into the outer layer of the skin — leads to lower antibody levels. However, a third vaccination boosts the antibody response.

Cases increasing in the Americas

The WHO announced on Wednesday that the Americas account for more than half of reported monkeypox cases, and the number of infections continues to increase in several countries in the region. Except for Canada, where the number of infections has been steadily decreasing.

The WHO Director-General Tedros Adhanom Ghebreyesus said during a press briefing that the outbreak is clearly slowing in some European countries, "demonstrating the effectiveness of public health interventions and community engagement to track infections and prevent transmission."

"With the right measures, this is an outbreak that can be stopped and, in regions that do not have animal-to-human transmission, this is a virus that can be eliminated," he said.


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