EPI UPDATE As of September 7, 54,707 total confirmed cases and 397 probable cases, including 18 deaths, have been reported to the WHO from 102 Member States across all 6 WHO regions. The US reports the most cases of any country globally, with 20,733 confirmed cases. The next 5 countries include Spain (6,749), Brazil (5,525), France (3,646), Germany (3,505), and the UK (3,484). Three other countries—Peru, Canada, and the Netherlands—have reported more than 1,000 cases. According to a September 7 global trends report from the WHO, the number of weekly reported new cases globally decreased by 25.5% in week 35 (August 29-September 4) (n=5,028 cases) compared to week 34 (August 22-28)) (n=6,746 cases). The majority of cases over the past 4 weeks were notified from the Americas (71.4%) and European (27.6%) regions.

As of September 6, US states reporting the highest number of cases are California (3,833), New York (3,526), Florida (2,126), Texas (1,859) and Georgia (1,512). As of August 31, 87,363 total specimens have been tested in the US with a cumulative test positivity rate of 30.9%, despite submitted specimens falling far short of current test capacity. The majority of cases continue to be among men, with Black/African American and Hispanic/Latino individuals accounting for 66.8% of reported cases during the week of August 27.

CAUTIOUS OPTIMISM Experts worldwide are expressing cautious optimism over signs that the monkeypox virus outbreak appears to be slowing. In addition to WHO data showing a decline in the number of weekly reported new cases last week, recent technical reports from the US CDC and the UK Health Security Agency (UKHSA) show new monkeypox cases are declining. In the US, the doubling time of the outbreak has slowed from 8 days to 25 days, but some uncertainties about the future trajectory of the outbreak remain. The CDC predicts the outbreak in the US will continue to grow over the next 2-4 weeks, with a declining growth rate. In the agency’s second outbreak report, the CDC outlines several possible future scenarios including containment, acceleration, or establishment of the virus in animal populations. Test positivity in the US has been between 20-25% since the week of August 13. A vast majority of transmission continues to occur among MSM, but cases are increasingly being reported in other populations. This could signal that the virus is beginning to reach new populations, case detection in other populations has improved, or some individuals are reluctant to disclose sexual history.

The pace of growth is also slowing in Canada, Spain, the UK, and other European countries. A UKHSA report asserts that the steady decline in cases is likely due to a combination of several factors, including behavior changes, improved diagnosis of patients, and saturation of the at-risk MSM population. 

VACCINATION TRENDS & SUPPLY Demand for monkeypox vaccination in the US shows signs of slowing as the 30 US jurisdictions collecting and publishing data have reported a drop in the number of first doses administered over the past 2 weeks. However, the proportion of second doses administered is increasing. Following the US FDA emergency use authorization (EUA) of a dose-sparing, intradermal injection strategy to allow healthcare providers to vaccinate 5 people, instead of one, from one vial of Jynneos vaccine, several jurisdictions have expanded their eligibility to populations other than gay, bisexual, or men who have sex with men (MSM). As of September 2, the US HHS has shipped all 772,753 vials of Jynneos vaccine requested by states and jurisdictions.

This week, HHS announced a US$19.8 million contract with AmerisourceBergen that will allow the US Strategic National Stockpile (SNS) to expand its distribution capacity and better support jurisdictional needs by significantly increasing the number of weekly shipments of vaccines and therapeutics and expanding delivery locations. Under the contract, the SNS will be able to make up to 2,500 shipments per week of frozen doses of Jynneos vaccine and shipments of SIGA Technologies' drug TPOXX to up to 2,500 locations. So far, the US government has purchased approximately 16.5 million vials of Jynneos, and the Biden administration is weighing how much of the supply to hold back for future monkeypox outbreaks and to maintain its defenses against the possibility of a bioterror attack involving smallpox.

The European Health Emergency Preparedness and Response Authority (HERA) this week secured an additional 170,920 doses of Jynneos from Bavarian Nordic, the manufacturer of the vaccine, effectively doubling its supply to 335,000 doses for EU Member States, Norway, and Iceland. It is unclear whether doses in this case refers to vials or the 5 doses per vial potentially possible with intradermal administration, which has also been authorized in Europe. 

NEUTRALIZING ANTIBODIES A preprint study posted to medRxiv on September 1 is raising concerns over the effectiveness of the Jynneos monkeypox vaccine. The research—which was conducted by scientists at the Erasmus University Medical Center in Rotterdam, Netherlands, and is not yet peer-reviewed—shows that the recommended 2-dose series of the Bavarian Nordic vaccine elicited relatively low levels of monkeypox virus neutralizing antibodies, raising the question of how well vaccinated individuals are protected. Dose-sparing regimens yielded even lower antibody level responses, while a third dose further boosted the antibody response. The researchers said that although the correlates of protection needed to protect individuals from monkeypox infection are unknown, individuals who get vaccinated should be cautious about assuming they are protected from infection. They also encouraged further study of vaccinated individuals to better assess vaccine efficacy and determine correlates of protection. Some experts warn that if the vaccine does not effectively prevent infection, health officials could face further erosion in the nation’s confidence in public health.

CARDIAC COMPLICATIONS A case study published last week in JACC: Case Reports is raising concerns of the possibility of viral myocarditis or other cardiac complications associated with monkeypox virus infection. A 31-year-old male with confirmed monkeypox infection developed acute myocarditis 5 days following the onset of monkeypox symptoms, according to the case report. The patient was treated with supportive care and had full clinical recovery within one week. The researchers reporting the case, which occurred in Portugal, said the report should help raise awareness of possible cardiac complications associated with monkeypox infection and encouraged further research to better describe the relationship between monkeypox and heart injury.