The SARS-CoV-2 BA.2.86 lineage, and its sublineage JN.1 in particular, achieved widespread transmission in the US during winter 2023-24. However, this surge in infections was not accompanied by COVID-19 hospitalizations and mortality commensurate with prior waves. To understand shifts in COVID-19 epidemiology associated with JN.1 emergence, we compared characteristics and clinical outcomes of time-matched cases infected with BA.2.86 lineages (predominantly representing JN.1) versus co-circulating XBB-derived lineages in December, 2023 and January, 2024. Cases infected with BA.2.86 lineages received greater numbers of COVID-19 vaccine doses, including XBB.1.5-targeted boosters, in comparison to cases infected with XBB-derived lineages. Additionally, cases infected with BA.2.86 lineages experienced greater numbers of documented prior SARS-CoV-2 infections. Cases infected with BA.2.86 lineages also experienced lower risk of progression to severe clinical outcomes requiring emergency department consultations or hospital admission. Sensitivity analyses suggested under-ascertainment of prior infections could not explain this apparent attenuation of severity. Our findings implicate escape from immunity acquired from prior vaccination or infection in the emergence of the JN.1 lineage and suggest infections with this lineage are less likely to experience clinically-severe disease. Monitoring of immune escape and clinical severity in emerging SARS-CoV-2 variants remains a priority to inform responses.

We used wastewater surveillance to identify 2 coronavirus disease outbreaks at a college in Maine, USA. Cumulative increases of >1 log(10) severe acute respiratory syndrome coronavirus 2 RNA in consecutive 24-hour composite samples preceded the outbreaks. For 76% of cases, RNA was identified in grab samples from residence halls <7 days before case discovery.

Large indoor gatherings pose a high risk for transmission of SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), and have the potential to be super-spreading events (1,2). Such events are associated with explosive growth, followed by sustained transmission (3). During August 7-September 14, 2020, the Maine Center for Disease Control and Prevention (MeCDC) investigated a COVID-19 outbreak linked to a wedding reception attended by 55 persons in a rural Maine town. In addition to the community outbreak, secondary and tertiary transmission led to outbreaks at a long-term care facility 100 miles away and at a correctional facility approximately 200 miles away. Overall, 177 COVID-19 cases were epidemiologically linked to the event, including seven hospitalizations and seven deaths (four in hospitalized persons). Investigation revealed noncompliance with CDC's recommended mitigation measures. To reduce transmission, persons should avoid large gatherings, practice physical distancing, wear masks, stay home when ill, and self-quarantine after exposure to a person with confirmed SARS-CoV-2 infection. Persons can work with local health officials to increase COVID-19 awareness and determine the best policies for organizing social events to prevent outbreaks in their communities.

As in many other small mammal groups from the Afrotropics, the number of species recognized within the genus Hylomyscus has increased considerably over the past dozen years. The last comprehensive review (2005) of the genus recognized eight species. Since that time, nine additional species have been elevated from synonymy (n = 4) or described as new (n = 5). Here we describe four additional new species supported by morphological and molecular evidence, all collected by the late William Stanley. Two of the new taxa are sympatric and come from the poorly known left bank (direction source to mouth) of the Congo River. One of these (Hylomyscus pygmaeus sp. nov.) is easily recognized, as it is tiny and significantly smaller than any known species of the genus; the second new species (Hylomyscus thornesmithae sp. nov.) is also small, and syntopic with the first. The third new species (Hylomyscus stanleyi sp. nov.), from the SW corner of Tanzania, is quite large and had been previously included within the hypodigm of Hylomyscus anselli following its recognition from within the synonymy of Hylomyscus denniae. The fourth species (Hylomyscus mpungamachagorum sp. nov.) is from Mahale Mountains National Park, western Tanzania. Our study reveals a much higher species diversity of the genus than previously known, providing insights into additional Afrotropical and Afromontane centers of endemism that require further exploration.