BACKGROUND: Understanding the risk of hospitalization from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections can guide effective public health interventions and severity assessments. This study calculated infection-hospitalization ratios (IHRs) and infection-case ratios (ICRs) to understand the relationship between SARS-CoV-2 infections, cases, and hospitalizations among different age groups during periods of Delta and Omicron variant predominance. METHODS: After calculating antinucleocapsid SARS-CoV-2 antibody seroprevalence using residual commercial laboratory serum specimens, 2 ratios were computed: (1) IHRs using coronavirus disease 2019 hospitalization data and (2) ICRs using Centers for Disease Control and Prevention surveillance data. Ratios were calculated across age groups (0-17, 18-49, 50-69, and ≥70 years) for 2 time periods (September-December 2021 [Delta] and December 2021-February 2022 [Omicron]). RESULTS: Pediatric IHRs increased from 76.7 during Delta to 258.4 during Omicron. Adult IHRs ranged from 3.0 (≥70 years) to 21.6 (18-49 years) during Delta and from 10.0 (≥70 years) to 119.1 (18-49 years) during Omicron. The pediatric ICR was lower during the Delta period (2.7) compared with the Omicron period (3.7). Adult ICRs (Delta: 1.1 [18-49 years] to 2.1 [70+ years]; Omicron: 2.2 [>70+ years] to 2.9 [50-69 years]) were lower than pediatric ICRs during both time periods. CONCLUSIONS: All age groups exhibited a lower proportion of infections associated with hospitalization in the Omicron period than the Delta period; the proportion of infections associated with hospitalization increased with each older age group. A lower proportion of SARS-CoV-2 infections were associated with reported cases in the Omicron period than in the Delta period among all age groups.

People with immunocompromising conditions (IC) are at increased risk of severe COVID-19 and death. These individuals show weaker immunogenicity following vaccination than individuals without IC, yet immunogenicity after SARS-CoV-2 infection is poorly understood. To address this gap, the presence of infection-induced antibodies in sera following a positive COVID-19 test result was compared between patients with and without IC. A commercial laboratory provided patient data gathered during July 2020-February 2022 on COVID-19 viral test results and antibody assay results, which included infection-induced (anti-N) antibody presence. Participants were categorized into having or not having IC based on if there was an indicative diagnostic code on their health record for a five-year period prior to the study period. Anti-N presence in sera from people with a positive COVID-19 test result was compared by IC status for four post-infection periods: 14-90, 91-180, 181-365, and 365+ days. A longitudinal, logistic regression produced adjusted odds ratios comparing anti-N prevalence among specimens with and without associated IC, adjusted for age, sex, residence in a metro area, and social vulnerability index (SVI) tertile. Data included 17,025 anti-N test results from 14,690 patients, 1,424 (9.7%) of which had at least one IC on record. In an adjusted comparison to patients without IC, patients with any IC were 0.61 times as likely to have infection-induced antibodies (99% CI: 0.40-0.93), during the 14-90 days following infection. Similar patterns were found when comparing people with two specific types of IC to people without any IC: (1) solid malignancies and (2) other intrinsic immune conditions. These findings stress the importance of prevention measures for people with IC, such as additional vaccination doses and consistent mask use before and after a documented infection.

We studied SARS-CoV-2 binding and neutralizing antibody titers among previously infected persons in the United States over time. We assayed SARS-CoV-2 spike protein receptor-binding domain and neutralizing antibody titers for a convenience sample of residual clinical serum specimens that had evidence of prior SARS-CoV-2 infection gathered during January 2021-February 2022. We correlated titers and examined them by age group (<18, 18-49, 50-64, and >65 years) across 4 different SARS-CoV-2 variant epochs. Among selected specimens, 30,967 had binding antibody titers and 744 had neutralizing titers available. Titers in specimens from children and adults correlated. In addition, mean binding antibody titers increased over time for all age groups, and mean neutralization titers increased over time for persons 16-49 and >65 years of age. Incorporating binding and neutralization antibody titers into infectious disease surveillance could provide a clearer picture of overall immunity and help target vaccination campaigns.

During September to December 2021, school mask policies to mitigate SARS-CoV-2 transmission varied throughout the US. We compared infection-induced seroprevalence estimates and estimated seroconversion among children residing in areas with and without school mask requirements. We estimated infection-induced seroprevalence among children in three age groups (5-17, 5-11, and 12-17 years) in areas with and without school district mask requirements for two time points: September 1-30, 2021 and December 15, 2021 to January 14, 2022. Robust Poisson regression models estimated population seroconversion over the semester among initially seronegative children. Permutation tests assessed for significant differences in the estimated population seroconversion due to incident infections by school district mask policy. Residing in an area with no school mask requirement was associated with higher infection-induced seroprevalence among children aged 5-17 years (adjusted prevalence ratio [aPR] = 1.18, 95% confidence interval [CI]: 1.10, 1.26), and those aged 5-11 years (aPR) = 1.21, 95% CI: 1.10, 1.32) and those aged 12-17 years (aPR = 1.16, 95% CI: 1.07, 1.26), compared with areas requiring masks in school. Estimated population seroconversion during the semester was also significantly higher among children in districts without mask policies than those with school mask requirements among all age groups (5-17 years: 23.7% vs 18.1%, P < 0.001; 5-11 years: 6.4% vs 4.5%, P = 0.002;12-17 years: 27.2% vs 21.0%, P < 0.001). During the U.S. Fall 2021 semester, areas with school mask requirements had lower infection-induced seroprevalence and an estimated lower proportion of seroconversion due to incident infection among school-aged children compared with areas without school mask requirements; causality cannot necessarily be inferred from these associations. IMPORTANCE: During the U.S. Fall 2021 school semester, the estimated proportion of previously uninfected school-aged children who experienced a first infection with SARS-CoV-2 was lower in areas where public school district policies required masks for all staff and students compared with areas where the school districts had no mask requirements. Because children are more likely than adults to experience asymptomatic or mild SARS-CoV-2 infections, the presence of infection-induced antibodies is a more accurate measure of infection history than clinical testing. The proportion of children with these antibodies (i.e., seroprevalence) can improve our understanding of SARS-CoV-2 by detecting more infections and eliminating potential bias due to local testing and reporting practices. Enhanced robustness of surveillance for respiratory infections in children, including records of mitigation policies in communities and schools, as well as seroprevalence data, would establish a better evidence base for policy decisions and response measures during future respiratory outbreaks.

Clade I monkeypox virus (MPXV), which can cause severe illness in more people than clade II MPXVs, is endemic in the Democratic Republic of the Congo (DRC), but the country has experienced an increase in suspected cases during 2023-2024. In light of the 2022 global outbreak of clade II mpox, the increase in suspected clade I cases in DRC raises concerns that the virus could spread to other countries and underscores the importance of coordinated, urgent global action to support DRC's efforts to contain the virus. To date, no cases of clade I mpox have been detected outside of countries in Central Africa where the virus is endemic. CDC and other partners are working to support DRC's response. In addition, CDC is enhancing U.S. preparedness by raising awareness, strengthening surveillance, expanding diagnostic testing capacity for clade I MPXV, ensuring appropriate specimen handling and waste management, emphasizing the importance of appropriate medical treatment, and communicating guidance on the recommended contact tracing, containment, behavior modification, and vaccination strategies.

Public health problems cannot be addressed without timely and accurate data. However, data that provide insight into populations that may be at disproportionate risk for disease, including people experiencing homelessness, are insufficiently captured. Although the associations between homelessness and disease have been well documented,1-6 data on housing status are not universally or consistently collected in routine public health data.7 Improving collection of data on housing status in public health data collection efforts is necessary to address health disparities among people experiencing homelessness and advance health equity research and practice. | Collecting data related to homelessness and disease is complicated for several reasons, but one of the most salient reasons is that defining homelessness is challenging. Several federal agencies use their own definitions to identify people who might be eligible for assistance programs, creating confusion about which definition should be used for public health purposes. In addition, definitions of homelessness at federal agencies have changed over time, further complicating the collection of homelessness data. The US Department of Housing and Urban Development (HUD) defines homelessness as lacking a fixed, regular, and adequate nighttime residence8; this definition includes both people with a primary nighttime residence of a public or private place not meant for human habitation (eg, cars, parks, public spaces, abandoned buildings) and people residing in temporary shelters (eg, emergency homeless shelter, transitional housing). The US Department of Education (DOE) uses a broader lens, defining homelessness to include school-aged children whose housing situation meets the HUD criteria for homelessness while also including those who share housing with other people by doubling up or couch surfing; those who live in motels, hotels, or trailer parks; and those who are abandoned at hospitals.9

Genomic surveillance of bacterial meningitis pathogens is essential for effective disease control globally, enabling identification of emerging and expanding strains and consequent public health interventions. While there has been a rise in the use of whole genome sequencing, this has been driven predominately by a subset of countries with adequate capacity and resources. Global capacity to participate in surveillance needs to be expanded, particularly in low and middle-income countries with high disease burdens. In light of this, the WHO-led collaboration, Defeating Meningitis by 2030 Global Roadmap, has called for the establishment of a Global Meningitis Genome Partnership that links resources for: N. meningitidis (Nm), S. pneumoniae (Sp), H. influenzae (Hi) and S. agalactiae (Sa) to improve worldwide co-ordination of strain identification and tracking. Existing platforms containing relevant genomes include: PubMLST: Nm (31,622), Sp (15,132), Hi (1,935), Sa (9,026); The Wellcome Sanger Institute: Nm (13,711), Sp (>24,000), Sa (6,200), Hi (1738); and BMGAP: Nm (8,785), Hi (2,030). A steering group is being established to coordinate the initiative and encourage high-quality data curation. Next steps include: developing guidelines on open-access sharing of genomic data; defining a core set of metadata; and facilitating development of user-friendly interfaces that represent publicly available data.