A study today in Morbidity and Mortality Weekly Report looked at a recent cluster of 40 mpox cases in Chicago and suggests that vaccine protection may wane over time, but vaccinated patients do well recovering at home, and vaccination protects against severe mpox.

The cluster, identified from March 18 to June 12, 2023, was notable because in the previous 2 months the Chicago Department of Health received notice of only 1 mpox case. And 55% of case-patients in the cluster reported having completed the two-dose schedule of Jynneos mpox vaccine prior to their illness or had received one dose of ACAM2000, a smallpox vaccine that also prevents mpox.

The 40 laboratory-confirmed cases included 22 (55%), 5 (13%), and 13 (33%) patients who had received, respectively, either 2 doses of Jynneos or 1 dose of ACAM2000 vaccine, 1 Jynneos dose, or no vaccine.

Most of the case-patients reported being vaccinated against the virus in July or August 2022; the median interval from receipt of the second Jynneos vaccine dose to mpox diagnosis was 8.4 months.

Vaccine protection against more severe illness

Patients who received only one dose of Jynneos or no vaccines had a higher prevalence of lesions affecting the genital (43% versus 6%) or ocular (29% versus none) mucosa, the authors said.

"Preliminary medical record review indicates that vaccinated patients experienced self-limited illness, managed in outpatient settings," the authors wrote. None of the patients who had been vaccinated required hospitalization, compared to two unvaccinated patients who were admitted for treatment.

Although the cause of this cluster has not yet been determined, leading hypotheses include a potential high number of sexual exposures.

"Although the cause of this cluster has not yet been determined, leading hypotheses include a potential high number of sexual exposures in a network with many vaccinated persons, decreased vaccine effectiveness due to waning of humoral immunity, or vaccine mishandling or administration errors," the authors concluded.

The Florida Department of Health (DOH) this week issued a mosquito warning after officials confirmed two cases of locally acquired malaria in the state, the first in 20 years.

People in Sarasota and Manatee counties contracted the mosquito-borne infection in late May. One of the patients has been treated and released, and the other is still being treated, the DOH said in a news release.

Officials confirmed that the cases are caused by the Plasmodium vivax malaria parasite, which is not as fatal as other malaria species. "Only infected Anopheles mosquitoes can transmit malaria to humans," the DOH said. It added, "Individuals in this area with symptoms of fever, chills, sweats, nausea/vomiting, and headache should seek immediate medical attention."

Individuals in this area with symptoms of fever, chills, sweats, nausea/vomiting, and headache should seek immediate medical attention.

The DOH said residents in the affected counties should take precautions, such as wearing long-sleeved shirts and pants, applying mosquito repellent, and avoiding areas with high mosquito populations, especially during sunrise and sunset, when mosquitos are most active. The agency also advised people to drain standing water to limit mosquito breeding grounds. A previous DOH release noted that response efforts include aerial and ground spraying to control mosquitoes in the affected counties.

These are the first locally acquired malaria cases confirmed in Florida since 2003, the Mirror reported today.

Cidara Therapeutics, of San Diego, announced today that the US Food and Drug Administration (FDA) has granted fast-track designation for CD388, the company's novel drug for preventing influenza A and B in adults at high risk for severe influenza, including those for whom vaccines are either ineffective or not indicated.

Fast-track designation aims to facilitate the development and expedite the review of drugs to treat serious conditions with unmet medical needs. The purpose is to get key new drugs to patients earlier. Companies that are granted this designation are given the opportunity for more frequent interactions with the FDA, and, if relevant criteria are met, eligibility for Priority Review.

Cidara is developing CD388, a drug-Fc conjugate candidate, in collaboration with Janssen Pharmaceuticals.

"We are pleased that the FDA has granted Fast Track designation for CD388, which emphasizes the unmet need for effective new prevention options for the many individuals who are not adequately protected by available influenza vaccines," said Jeffrey Stein, PhD, Cidara president and CEO.

[The approval] emphasizes the unmet need for effective new prevention options for the many individuals who are not adequately protected by available influenza vaccines.

Cidara recently announced promising interim efficacy and safety data from an ongoing phase 2a study being conducted in cooperation with Janssen. The study is evaluating how well CD388 prevents infection from the influenza A H3N2 strain.