CONTEXT: Federal public health travel restrictions (FPHTR) in the United States are implemented for persons who meet specific criteria to prevent spread of communicable diseases of public health concern. FPHTR can mitigate the risk of disease transmission during air travel and mitigating disease translocation between geographic areas. OBJECTIVE: To characterize and determine the extent of FPHTR implementation during the COVID-19 pandemic. DESIGN: Secondary data analysis. SETTING AND PARTICIPANTS: This report reviewed the U.S. public health response for 3010 persons traveling within, into, and out of, the U.S. who were placed on federal public health travel restrictions during the COVID-19 outbreak from January 1, 2020 to April 6, 2022. MAIN OUTCOME MEASURE: Total number and characteristics of persons with SARS-CoV-2 infection or high-risk exposure added to FPHTR. RESULTS: During this period, FPHTR were implemented for 3010/5460 (55%) persons who were reported to CDC as having tested positive for SARS-CoV-2, or being identified as close contacts of a person with COVID-19, with intention to travel. Of those added to FPHTR lists, 2023/3010 (67%) had confirmed SARS-CoV-2 infection, 975/3010 (32%) were close contacts, and 12/3010 (0.4%) were reasonably believed to have COVID-19 but later confirmed to have another diagnosis and removed. Twenty-six percent (793/3010) of SARS-CoV-2-related FPHTR were for persons reported to CDC after testing positive for SARS-CoV-2 at a testing site located within a U.S. airport. CONCLUSIONS: The extensive application of FPHTR for more than 3000 persons over a period of 29 months during the COVID-19 pandemic was unprecedented. The additional use of FPHTR required extraordinary effort and collaboration among CDC staff and local/state public health agencies for case investigation, reporting, exchange of information, and communication with travelers for case management. Use of this tool should be considered within the context current transmission risk and disease severity.

In the early years of the COVID-19 pandemic, unprecedented public health measures were designed and implemented to mitigate the spread of SARS-CoV-2. On January 26, 2021, US Centers for Disease Control and Prevention (CDC) staff began daily audits of documents of arriving passengers at 18 US international ports of entry to ensure documentation of either a negative predeparture antigen or nucleic acid amplification test result for SARS-CoV-2 or recent recovery from COVID-19. This case study briefly describes the results of those audits. The CDC found a very low rate of issues overall. Of the 483,251 passengers selected for audit, 2,142 (0.44%) had issues with their COVID-19 test documentation and 1,182 (0.24%) provided documentation of recovery from COVID-19 rather than a negative test result. The low rate of issues noted during traveler audits indicated airlines were largely compliant with the order. However, the burden of SARS-CoV-2 infections within the United States was high during much of this period, which suggests that implementing a predeparture testing requirement earlier in the pandemic might have had more impact on spread. Digital solutions could reduce the burden of similar interventions in the future on airlines, public health authorities, and other partners. © Mary Ann Liebert, Inc.

We describe the first cases of natural SARS-CoV-2 infection detected in animals in the United States. In March 2020, four tigers and three lions at the Bronx Zoo developed mild respiratory signs. SARS-CoV-2 RNA was detected by rRT-PCR in respiratory secretions and/or feces from all seven affected animals; viral RNA and/or antibodies were detected in their keepers. SARS-CoV-2 was isolated from respiratory secretions or feces from three affected animals; in situ hybridization co-localized viral RNA with cellular damage. Whole genome sequence and haplotype network analyses showed tigers and lions were infected with two different SARS-CoV-2 strains, suggesting independent viral introductions. The source of SARS-CoV-2 infection in the lions is unknown. Epidemiological data and genetic similarities between keeper and tiger viruses indicate human to animal transmission.Competing Interest StatementThe authors have declared no competing interest.

Although reinfections with SARS-CoV-2 have occurred in the United States with increasing frequency, U.S. epidemiologic trends in reinfections and associated severe outcomes have not been characterized. Weekly counts of SARS-CoV-2 reinfections, total infections, and associated hospitalizations and deaths reported by 18 U.S. jurisdictions during September 5, 2021-December 31, 2022, were analyzed overall, by age group, and by five periods of SARS-CoV-2 variant predominance (Delta and Omicron [BA.1, BA.2, BA.4/BA.5, and BQ.1/BQ.1.1]). Among reported reinfections, weekly trends in the median intervals between infections and frequencies of predominant variants during previous infections were calculated. As a percentage of all infections, reinfections increased substantially from the Delta (2.7%) to the Omicron BQ.1/BQ.1.1 (28.8%) periods; during the same periods, increases in the percentages of reinfections among COVID-19-associated hospitalizations (from 1.9% [Delta] to 17.0% [Omicron BQ.1/BQ.1.1]) and deaths (from 1.2% [Delta] to 12.3% [Omicron BQ.1/BQ.1.1]) were also substantial. Percentages of all COVID-19 cases, hospitalizations, and deaths that were reinfections were consistently higher across variant periods among adults aged 18-49 years compared with those among adults aged ≥50 years. The median interval between infections ranged from 269 to 411 days by week, with a steep decline at the start of the BA.4/BA.5 period, when >50% of reinfections occurred among persons previously infected during the Alpha variant period or later. To prevent severe COVID-19 outcomes, including those following reinfection, CDC recommends staying up to date with COVID-19 vaccination and receiving timely antiviral treatments, when eligible.

Despite numerous barriers to transmission, zoonoses are the major cause of emerging infectious diseases in humans. Among these, severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), and ebolaviruses have killed thousands; the human immunodeficiency virus (HIV) has killed millions. Zoonoses and human-to-animal cross-species transmission are driven by human actions and have important management, conservation, and public health implications. The current SARS-CoV-2 pandemic, which presumably originated from an animal reservoir, has killed more than half a million people around the world and cases continue to rise. In March 2020, New York City was a global epicenter for SARS-CoV-2 infections. During this time, four tigers and three lions at the Bronx Zoo, NY, developed mild, abnormal respiratory signs. We detected SARS-CoV-2 RNA in respiratory secretions and/or feces from all seven animals, live virus in three, and colocalized viral RNA with cellular damage in one. We produced nine whole SARS-CoV-2 genomes from the animals and keepers and identified different SARS-CoV-2 genotypes in the tigers and lions. Epidemiologic and genomic data indicated human-to-tiger transmission. These were the first confirmed cases of natural SARS-CoV-2 animal infections in the United States and the first in nondomestic species in the world. We highlight disease transmission at a nontraditional interface and provide information that contributes to understanding SARS-CoV-2 transmission across species.IMPORTANCE The human-animal-environment interface of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an important aspect of the coronavirus disease 2019 (COVID-19) pandemic that requires robust One Health-based investigations. Despite this, few reports describe natural infections in animals or directly link them to human infections using genomic data. In the present study, we describe the first cases of natural SARS-CoV-2 infection in tigers and lions in the United States and provide epidemiological and genetic evidence for human-to-animal transmission of the virus. Our data show that tigers and lions were infected with different genotypes of SARS-CoV-2, indicating two independent transmission events to the animals. Importantly, infected animals shed infectious virus in respiratory secretions and feces. A better understanding of the susceptibility of animal species to SARS-CoV-2 may help to elucidate transmission mechanisms and identify potential reservoirs and sources of infection that are important in both animal and human health.

BACKGROUND: The timing of the initial spread of hepatitis C virus genotype 1a in North America is controversial. In particular, how and when hepatitis C virus reached extraordinary prevalence in specific demographic groups remains unclear. We quantified, using all available hepatitis C virus sequence data and phylodynamic methods, the timing of the spread of hepatitis C virus genotype 1a in North America. METHODS: We screened 45 316 publicly available sequences of hepatitis C virus genotype 1a for location and genotype, and then did phylogenetic analyses of available North American sequences from five hepatitis C virus genes (E1, E2, NS2, NS4B, NS5B), with an emphasis on including as many sequences with early collection dates as possible. We inferred the historical population dynamics of this epidemic for all five gene regions using Bayesian skyline plots. FINDINGS: Most of the spread of genotype 1a in North America occurred before 1965, and the hepatitis C virus epidemic has undergone relatively little expansion since then. The effective population size of the North American epidemic stabilised around 1960. These results were robust across all five gene regions analysed, although analyses of each gene separately show substantial variation in estimates of the timing of the early exponential growth, ranging roughly from 1940 for NS2, to 1965 for NS4B. INTERPRETATION: The expansion of genotype 1a before 1965 suggests that nosocomial or iatrogenic factors rather than past sporadic behavioural risk (ie, experimentation with injection drug use, unsafe tattooing, high risk sex, travel to high endemic areas) were key contributors to the hepatitis C virus epidemic in North America. Our results might reduce stigmatisation around screening and diagnosis, potentially increasing rates of screening and treatment for hepatitis C virus. FUNDING: The Canadian Institutes of Health Research, Michael Smith Foundation for Health Research, and BC Centre for Excellence in HIV/AIDS.

Improved surveillance methods are needed to better understand the current hepatitis C virus (HCV) disease burden and to monitor the impact of prevention and treatment interventions on HCV transmission dynamics. Sanger sequencing (HCV NS5B, HVR1 and Core-E1-HVR1) and phylogenetics were applied to samples from individuals diagnosed with HCV in British Columbia, Canada in 2011. This included individuals with two or three sequential samples collected <1year apart. Patristic distances between sequential samples were used to set cutoffs to identify recent transmission clusters. Factors associated with transmission clustering were analyzed using logistic regression. From 618 individuals, 646 sequences were obtained. Depending on the cutoff used, 63 (10%) to 92 (15%) unique individuals were identified within transmission clusters of predicted recent origin. Clustered individuals were more likely to be <40years old (Adjusted Odds Ratio (AOR) 2.12, 95% CI 1.21-3.73), infected with genotype 1a (AOR 6.60, 95% CI 1.98-41.0), and to be seroconverters with estimated infection duration of <1year (AOR 3.13, 95% CI 1.29-7.36) or >1year (AOR 2.19, 95% CI 1.22-3.97). CONCLUSION: Systematic application of molecular phylogenetics may be used to enhance traditional surveillance methods through identification of recent transmission clusters.