Cross-Neutralizing and Protective Human Antibody Specificities to Poxvirus Infections.

Monkeypox (MPXV) and cowpox (CPXV) are emerging agents that cause severe human infections on an intermittent basis, and variola virus (VARV) has potential for use as an agent of bioterror. Vaccinia immune globulin (VIG) has been used therapeutically to treat severe orthopoxvirus infections but is in short supply. We generated a large panel of orthopoxvirus-specific human monoclonal antibodies (Abs) from immune subjects to investigate the molecular basis of broadly neutralizing antibody responses for diverse orthopoxviruses. Detailed analysis revealed the principal neutralizing antibody specificities that are cross-reactive for VACV, CPXV, MPXV, and VARV and that are determinants of protection in murine challenge models. Optimal protection following respiratory or systemic infection required a mixture of Abs that targeted several membrane proteins, including proteins on enveloped and mature virion forms of virus. This work reveals orthopoxvirus targets for human Abs that mediate cross-protective immunity and identifies new candidate Ab therapeutic mixtures to replace VIG.

Genomic Surveillance for SARS-CoV-2 Variants: Circulation of Omicron XBB and JN.1 Lineages - United States, May 2023-September 2024.

CDC continues to track the evolution of SARS-CoV-2, including the Omicron variant and its descendants, using national genomic surveillance. This report summarizes U.S. trends in variant proportion estimates during May 2023-September 2024, a period when SARS-CoV-2 lineages primarily comprised descendants of Omicron variants XBB and JN.1. During summer and fall 2023, multiple descendants of XBB with immune escape substitutions emerged and reached >10% prevalence, including EG.5-like lineages by June 24, FL.1.5.1-like lineages by August 5, HV.1 lineage by September 30, and HK.3-like lineages by November 11. In winter 2023, the JN.1 variant emerged in the United States and rapidly attained predominance nationwide, representing a substantial genetic shift (>30 spike protein amino acid differences) from XBB lineages. Descendants of JN.1 subsequently circulated and reached >10% prevalence, including KQ.1-like and KP.2-like lineages by April 13, KP.3 and LB.1-like lineages by May 25, and KP.3.1.1 by July 20. Surges in COVID-19 cases occurred in winter 2024 during the shift to JN.1 predominance, as well as in summer 2023 and 2024 during circulation of multiple XBB and JN.1 descendants, respectively. The ongoing evolution of the Omicron variant highlights the importance of continued genomic surveillance to guide medical countermeasure development, including the selection of antigens for updated COVID-19 vaccines.

Early Detection and Surveillance of the SARS-CoV-2 Variant BA.2.86 - Worldwide, July-October 2023.

Early detection of emerging SARS-CoV-2 variants is critical to guiding rapid risk assessments, providing clear and timely communication messages, and coordinating public health action. CDC identifies and monitors novel SARS-CoV-2 variants through diverse surveillance approaches, including genomic, wastewater, traveler-based, and digital public health surveillance (e.g., global data repositories, news, and social media). The SARS-CoV-2 variant BA.2.86 was first sequenced in Israel and reported on August 13, 2023. The first U.S. COVID-19 case caused by this variant was reported on August 17, 2023, after a patient received testing for SARS-CoV-2 at a health care facility on August 3. In the following month, eight additional U.S. states detected BA.2.86 across various surveillance systems, including specimens from health care settings, wastewater surveillance, and traveler-based genomic surveillance. As of October 23, 2023, sequences have been reported from at least 32 countries. Continued variant tracking and further evidence are needed to evaluate the full public health impact of BA.2.86. Timely genomic sequence submissions to global public databases aided early detection of BA.2.86 despite the decline in the number of specimens being sequenced during the past year. This report describes how multicomponent surveillance and genomic sequencing were used in real time to track the emergence and transmission of the BA.2.86 variant. This surveillance approach provides valuable information regarding implementing and sustaining comprehensive surveillance not only for novel SARS-CoV-2 variants but also for future pathogen threats.

Household Transmission and Symptomology of Severe Acute Respiratory Syndrome Coronavirus 2 Alpha Variant among Children-California and Colorado, 2021.

OBJECTIVE: To assess the household secondary infection risk (SIR) of B.1.1.7 (Alpha) and non-Alpha lineages of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among children. STUDY DESIGN: During January to April 2021, we prospectively followed households with a SARS-CoV-2 infection. We collected questionnaires, serial nasopharyngeal swabs for reverse transcription polymerase chain reaction testing and whole genome sequencing, and serial blood samples for serology testing. We calculated SIRs by primary case age (pediatric vs adult), household contact age, and viral lineage. We evaluated risk factors associated with transmission and described symptom profiles among children. RESULTS: Among 36 households with pediatric primary cases, 21 (58%) had secondary infections. Among 91 households with adult primary cases, 51 (56%) had secondary infections. SIRs among pediatric and adult primary cases were 45% and 54%, respectively (OR, 0.79; 95% CI, 0.41-1.54). SIRs among pediatric primary cases with Alpha and non-Alpha lineage were 55% and 46%, respectively (OR, 1.52; 95% CI, 0.51-4.53). SIRs among pediatric and adult household contacts were 55% and 49%, respectively (OR, 1.01; 95% CI, 0.68-1.50). Among pediatric contacts, no significant differences in the odds of acquiring infection by demographic or household characteristics were observed. CONCLUSIONS: Household transmission of SARS-CoV-2 from children and adult primary cases to household members was frequent. The risk of secondary infection was similar among child and adult household contacts. Among children, household transmission of SARS-CoV-2 and the risk of secondary infection was not influenced by lineage. Continued mitigation strategies (eg, masking, physical distancing, vaccination) are needed to protect at-risk groups regardless of virus lineage circulating in communities.

The Relationship Between Physical Activity and Health-Related Quality of Life in People With Dementia: An Observational Study.

Recent research suggests the positive effect of physical activity on health-related quality of life in people with dementia may be mediated through improved activities of daily living and reduced depressive symptoms. One hundred and twenty-four people with dementia and their informal carers were recruited from the South East of England for this observational study. A subset of participants wore an accelerometer for 30 days. A series of bivariate analyses were completed, alongside mediation analyses. In people with mild to moderate severity dementia, weak positive associations were widely reported between physical activity indices and health-related quality of life, though only a single association reached statistical significance (rs = .25, p = .03). Mediation analysis revealed no significant indirect effects across the models after controlling for cognition. Future research needs to explore such relationships with a greater emphasis on the modality and psychosocial components of physical activity rather than just frequency, duration, and intensity.

Psychometric properties and feasibility of use of dementia specific quality of life instruments for use in care settings: a systematic review.

BACKGROUND: Over 400,000 people live in care home settings in the UK. One way of understanding and improving the quality of care provided is by measuring and understanding the quality of life (QoL) of those living in care homes. This review aimed to identify and examine the psychometric properties including feasibility of use of dementia-specific QoL measures developed or validated for use in care settings. DESIGN: Systematic review. METHODS: Instruments were identified using four electronic databases (PubMed, PsycINFO, Web of Science, and CINAHL) and lateral search techniques. Searches were conducted in January 2017. Studies which reported on the development and/or validation of dementia specific QoL instruments for use in care settings written in English were eligible for inclusion. The methodological quality of the studies was assessed using the COSMIN checklist. Feasibility was assessed using a checklist developed specifically for the review. RESULTS: Six hundred and sixteen articles were identified in the initial search. After de-duplication, screening and further lateral searches were performed, 25 studies reporting on 9 dementia-specific QoL instruments for use in care home settings were included in the review. Limited evidence was available on the psychometric properties of many instruments identified. Higher-quality instruments were not easily accessible or had low feasibility of use. CONCLUSIONS: Few high-quality instruments of QoL validated for use in care home settings are readily or freely available. This review highlights the need to develop a well-validated measure of QoL for use within care homes that is also feasible and accessible.

Barriers, motivators and facilitators of physical activity in people with dementia and their family carers in England: dyadic interviews.

INTRODUCTION: Physical activity may have a number of physical and mental health benefits for people with dementia and their carers. However, there is limited evidence about factors that influence physical activity participation in these groups. This study therefore looks at the barriers, facilitators and motivators of physical activity in people with dementia, from both the perspective of the person with dementia and their carer. METHOD: Thirty participants (15 sets of community-dwelling people with dementia and their family carers) were recruited from the South East of England. The participants took part in semi-structured dyadic interviews about their views of physical activity. Interviews were analysed using inductive thematic analysis at an individual level and comparisons were made between the groups. RESULTS: Common motivator themes across persons with dementia and family carers were emotional and physical wellbeing, and social connectedness. Physical health was seen as a common barrier in both groups. Physical activity in the person with dementia was encouraged and supported by the family carer. For the carer, their caring role, and limited time acted as barriers to their participation. CONCLUSION: Themes such as social connectedness, positive emotion and health were seen as key motivators to physical activity, which indicate that people with dementia and carers use physical activity as a means to maintain and improve their quality of life. Supporting family members to better facilitate such activities could encourage physical activity in people with dementia.

The effect of a dementia awareness class on changing dementia attitudes in adolescents.

BACKGROUND: Current evidence suggests that negative and stigmatising attitudes towards dementia may develop at a young age. There are a number of dementia education and awareness initiatives aimed at reducing stigma, though they have not been robustly evaluated to establish the impact on dementia attitudes or suitability in adolescent populations. This study explored the efficacy and satisfaction of one such initiative (Dementia Friends) in a British adolescent sample. METHODS: 301 adolescents (M = 12.6 years old, SD = 0.73) were assigned to either receive Dementia Friends (a 60-min interactive class that teaches about dementia and its effects on people's lives) or education as usual. All participants completed a series of validated questionnaires pre- and post-intervention, related to dementia attitudes (Brief A-ADS and KIDS). RESULTS: Adolescents in the dementia awareness group showed little to no improvements between time-points. The change scores in the dementia awareness group did not significantly differ to the control group based on both KIDS (d = - 0.003, p = 0.98) and Brief A-ADS (d = 0.14, p = 0.13) measures. There was no Group x Time effect after controlling for confounding variables. CONCLUSIONS: Dementia Friends is successful in terms of reach and impact, though this study suggests that it may fall short of achieving its goal of improving attitudes towards dementia. Importantly, Dementia Friends did not have a negative effect on attitudes, and the majority of adolescents enjoyed the sessions. It is important that these findings are replicated in a larger randomised-controlled study.

Adolescents' experiences and perceptions of dementia.

Objectives: There is a lack of understanding about how adolescents perceive dementia, and what their dementia related experiences are. Without such information, it is hard to make a case for the need to raise awareness of dementia in adolescents, and the best strategies to achieve this.Methods: In a cohort of 901 adolescents (aged 13-18) from the South East of England, we explored what the experiences and perceptions of dementia were using a series of questionnaires. Descriptive data of individual items were reported, comparing differences between genders.Results: The adolescents within this study tended to have positive or neutral attitudes towards dementia, though there was evidence that a proportion of adolescents had misconceptions or held negative attitudes (e.g. 28.5% of adolescents disagreed with the statement 'In general, I have positive attitudes about people with dementia'). We also identified that the adolescents had a range of experiences of dementia including providing some form of care for someone with dementia (23.2%), though most had indirect contact with dementia through TV and movies (77.3%), or adverts (80.2%). Females nearly always had better attitudes towards dementia and had significantly more contact with dementia.Conclusions: Considering that adolescents are already forming negative attitudes and misconceptions of dementia, it is important that we raise awareness about dementia in this age group.

Use of Physical Activity Questionnaires in People With Dementia: A Scoping Review.

Physical activity questionnaires are an important means to assess habitual physical activity. It remains unclear what questionnaires are used and whether they are appropriate for people with dementia who have impaired information recall but are also often largely sedentary. This scoping review aimed to identify and quantify the use of physical activity questionnaires within a dementia population. Eighteen studies met the inclusion criteria for this review. The majority of studies used questionnaires that were validated for use within an older adult population (e.g., Modified Baecke Questionnaire for the Elderly), though none had specifically been validated for use in people with dementia. Interestingly, just over half of the studies (N = 10, 55.6%) adapted the questionnaires from the original validated version by allowing a proxy to provide input to the responses. Future research needs to robustly validate the use of proxy-report measures of physical activity in people with dementia.

Effect of a Low-Intensity PSA-Based Screening Intervention on Prostate Cancer Mortality: The CAP Randomized Clinical Trial.

Importance: Prostate cancer screening remains controversial because potential mortality or quality-of-life benefits may be outweighed by harms from overdetection and overtreatment. Objective: To evaluate the effect of a single prostate-specific antigen (PSA) screening intervention and standardized diagnostic pathway on prostate cancer-specific mortality. Design, Setting, and Participants: The Cluster Randomized Trial of PSA Testing for Prostate Cancer (CAP) included 419 582 men aged 50 to 69 years and was conducted at 573 primary care practices across the United Kingdom. Randomization and recruitment of the practices occurred between 2001 and 2009; patient follow-up ended on March 31, 2016. Intervention: An invitation to attend a PSA testing clinic and receive a single PSA test vs standard (unscreened) practice. Main Outcomes and Measures: Primary outcome: prostate cancer-specific mortality at a median follow-up of 10 years. Prespecified secondary outcomes: diagnostic cancer stage and Gleason grade (range, 2-10; higher scores indicate a poorer prognosis) of prostate cancers identified, all-cause mortality, and an instrumental variable analysis estimating the causal effect of attending the PSA screening clinic. Results: Among 415 357 randomized men (mean [SD] age, 59.0 [5.6] years), 189 386 in the intervention group and 219 439 in the control group were included in the analysis (n = 408 825; 98%). In the intervention group, 75 707 (40%) attended the PSA testing clinic and 67 313 (36%) underwent PSA testing. Of 64 436 with a valid PSA test result, 6857 (11%) had a PSA level between 3 ng/mL and 19.9 ng/mL, of whom 5850 (85%) had a prostate biopsy. After a median follow-up of 10 years, 549 (0.30 per 1000 person-years) died of prostate cancer in the intervention group vs 647 (0.31 per 1000 person-years) in the control group (rate difference, -0.013 per 1000 person-years [95% CI, -0.047 to 0.022]; rate ratio [RR], 0.96 [95% CI, 0.85 to 1.08]; P = .50). The number diagnosed with prostate cancer was higher in the intervention group (n = 8054; 4.3%) than in the control group (n = 7853; 3.6%) (RR, 1.19 [95% CI, 1.14 to 1.25]; P < .001). More prostate cancer tumors with a Gleason grade of 6 or lower were identified in the intervention group (n = 3263/189 386 [1.7%]) than in the control group (n = 2440/219 439 [1.1%]) (difference per 1000 men, 6.11 [95% CI, 5.38 to 6.84]; P < .001). In the analysis of all-cause mortality, there were 25 459 deaths in the intervention group vs 28 306 deaths in the control group (RR, 0.99 [95% CI, 0.94 to 1.03]; P = .49). In the instrumental variable analysis for prostate cancer mortality, the adherence-adjusted causal RR was 0.93 (95% CI, 0.67 to 1.29; P = .66). Conclusions and Relevance: Among practices randomized to a single PSA screening intervention vs standard practice without screening, there was no significant difference in prostate cancer mortality after a median follow-up of 10 years but the detection of low-risk prostate cancer cases increased. Although longer-term follow-up is under way, the findings do not support single PSA testing for population-based screening. Trial Registration: ISRCTN Identifier: ISRCTN92187251.

Contemporary accuracy of death certificates for coding prostate cancer as a cause of death: Is reliance on death certification good enough? A comparison with blinded review by an independent cause of death evaluation committee.

BACKGROUND: Accurate cause of death assignment is crucial for prostate cancer epidemiology and trials reporting prostate cancer-specific mortality outcomes. METHODS: We compared death certificate information with independent cause of death evaluation by an expert committee within a prostate cancer trial (2002-2015). RESULTS: Of 1236 deaths assessed, expert committee evaluation attributed 523 (42%) to prostate cancer, agreeing with death certificate cause of death in 1134 cases (92%, 95% CI: 90%, 93%). The sensitivity of death certificates in identifying prostate cancer deaths as classified by the committee was 91% (95% CI: 89%, 94%); specificity was 92% (95% CI: 90%, 94%). Sensitivity and specificity were lower where death occurred within 1 year of diagnosis, and where there was another primary cancer diagnosis. CONCLUSIONS: UK death certificates accurately identify cause of death in men with prostate cancer, supporting their use in routine statistics. Possible differential misattribution by trial arm supports independent evaluation in randomised trials.

Standardisation of information submitted to an endpoint committee for cause of death assignment in a cancer screening trial ­ lessons learnt from CAP (Cluster randomised triAl of PSA testing for Prostate cancer).

BACKGROUND: In cancer screening trials where the primary outcome is target cancer-specific mortality, the unbiased determination of underlying cause of death (UCD) is crucial. To minimise bias, the UCD should be independently verified by expert reviewers, blinded to death certificate data and trial arm. We investigated whether standardising the information submitted for UCD assignment in a population-based randomised controlled trial of prostate-specific antigen (PSA) testing for prostate cancer reduced the reviewers' ability to correctly guess the trial arm. METHODS: Over 550 General Practitioner (GP) practices (>415,000 men aged 50-69 years) were cluster-randomised to PSA testing (intervention arm) or the National Health Service (NHS) prostate cancer risk management programme (control arm) between 2001 and 2007. Assignment of UCD was by independent reviews of researcher-written clinical vignettes that masked trial arm and death certificate information. A period of time after the process began (the initial phase), we analysed whether the reviewers could correctly identify trial arm from the vignettes, and the reasons for their choice. This feedback led to further standardisation of information (second phase), after which we re-assessed the extent of correct identification of trial arm. RESULTS: 1099 assessments of 509 vignettes were completed by January 2014. In the initial phase (n = 510 assessments), reviewers were unsure of trial arm in 33% of intervention and 30% of control arm assessments and were influenced by symptoms at diagnosis, PSA test result and study-specific criteria. In the second phase (n = 589), the respective proportions of uncertainty were 45% and 48%. The percentage of cases whereby reviewers were unable to determine the trial arm was greater following the standardisation of information provided in the vignettes. The chances of a correct guess and an incorrect guess were equalised in each arm, following further standardisation. CONCLUSIONS: It is possible to mask trial arm from cause of death reviewers, by using their feedback to standardise the information submitted to them. TRIAL REGISTRATION: ISRCTN92187251.

Design and Optimization of a Monkeypox virus Specific Serological Assay.

Monkeypox virus (MPXV), a member of the Orthopoxvirus (OPXV) genus, is a zoonotic virus, endemic to central and western Africa that can cause smallpox-like symptoms in humans with fatal outcomes in up to 15% of patients. The incidence of MPXV infections in the Democratic Republic of the Congo, where the majority of cases have occurred historically, has been estimated to have increased as much as 20-fold since the end of smallpox vaccination in 1980. Considering the risk global travel carries for future disease outbreaks, accurate epidemiological surveillance of MPXV is warranted as demonstrated by the recent Mpox outbreak, where the majority of cases were occurring in non-endemic areas. Serological differentiation between childhood vaccination and recent infection with MPXV or other OPXVs is difficult due to the high level of conservation within OPXV proteins. Here, a peptide-based serological assay was developed to specifically detect exposure to MPXV. A comparative analysis of immunogenic proteins across human OPXVs identified a large subset of proteins that could potentially be specifically recognized in response to a MPXV infection. Peptides were chosen based upon MPXV sequence specificity and predicted immunogenicity. Peptides individually and combined were screened in an ELISA against serum from well-characterized Mpox outbreaks, vaccinee sera, and smallpox sera collected prior to eradication. One peptide combination was successful with ~86% sensitivity and ~90% specificity. The performance of the assay was assessed against the OPXV IgG ELISA in the context of a serosurvey by retrospectively screening a set of serum specimens from the region in Ghana believed to have harbored the MPXV-infected rodents involved in the 2003 United States outbreak.

Care home staff perceptions of implementing a quality of life instrument into routine care practice: A qualitative study.

Quality of life is an important outcome in older-adult care. Measuring resident quality of life may offer ways to improve it and to improve quality of care. However, in the UK quality of life is rarely measured as a part of routine care. Our study aimed to understand the views of care home staff about using a quality of life instrument as a part of routine care in order to support its implementation into routine practice. In a qualitative study, we conducted 35 interviews with care home staff and two focus groups with four care home managers from three care homes in East Sussex, England. Data were collected between September 2015 and February 2016. Care staff and managers were aged on average 40 (SD = 12.2) and 43.7 (SD = 14.4) years and had worked in the care sector an average of 11.4 (SD = 10.2) and 23.7 (SD = 14.1) years, respectively. Participants were predominantly female and white British. Interviews and focus groups were analysed using thematic analysis. Findings identified two overarching themes of 'Perceived gains' and 'Implementation'. Overall, there was a lot of positivity towards using a quality of life instrument in routine practice. This positivity was an important feature in how the instrument was perceived as fitting into practice. Participants identified several barriers and discussed how to overcome them. Results from the study demonstrate that routine measurement of quality of life is positively received by care staff. They believed that measuring quality of life as a part of care practice could lead to improvements in resident quality of life, staff knowledge and understanding and care practices. The findings suggest that routinely measuring quality of life as a part of normal care could also have more far-reaching effects on the provision of person-centred care provided by care staff.

Measuring adolescent attitudes towards dementia: The revalidation and refinement of the A-ADS.

The A-ADS is one the first validated measures of attitudes of dementia in adolescents, though further validation is needed. 630 adolescents were recruited from secondary schools in England. A Principal Component Analysis was completed (n = 230) followed by a Confirmatory Factor Analysis (n = 400). Reducing the A-ADS into a single factor, 13-item measure (Brief A-ADS) improved the model fit of the measure (χ2 = 182.75, DF = 65, CMIN/DF = 2.81, p < 0.001, CFI = 0.90, RMSEA = 0.07). The scale demonstrated good internal consistency, good predictive and concurrent validity. Building on the validation of the A-ADS, the Brief A-ADS is suitable to capture attitudes towards dementia amongst adolescents.

COVID-19 health information needs of older adults from ethnic minority groups in the UK: a qualitative study.

OBJECTIVE: This study aimed to identify the COVID-19 health information needs of older adults from ethnic minority groups in the UK. STUDY DESIGN: A qualitative study using semistructured interviews. SETTING AND PARTICIPANTS: Indian and Nepalese older adults (≥65 years), their families (≥18 years) and healthcare professionals (HCPs) (≥18 years) engaging with these communities. Participants were recruited between July and December 2020 from Kent, Surrey and Sussex through community organisations. RESULTS: 24 participants took part in the study; 13 older adults, 7 family members and 4 HCPs. Thirteen participants were female, and the majority (n=17) spoke a language other than English at home. Older participants mostly lived in multigenerational households, and family and community were key for providing support and communicating about healthcare needs. Participants' knowledge of COVID-19 varied widely; some spoke confidently about the subject, while others had limited information. Language and illiteracy were key barriers to accessing health information. Participants highlighted the need for information in multiple formats and languages, and discussed the importance of culturally appropriate avenues, such as community centres and religious sites, for information dissemination. CONCLUSION: This study, undertaken during the COVID-19 pandemic, provides insight into how health information can be optimised for ethnic minority older adults in terms of content, format and cultural relevance. The study highlights that health information interventions should recognise the intersection between multigenerational living, family structure, and the health and well-being of older adults, and should promote intergenerational discussion.

Household characteristics associated with surface contamination of SARS-CoV-2 and frequency of RT-PCR and viral culture positivity-California and Colorado, 2021.

While risk of fomite transmission of SARS-CoV-2 is considered low, there is limited environmental data within households. This January-April 2021 investigation describes frequency and types of surfaces positive for SARS-CoV-2 by real-time reverse transcription polymerase chain reaction (RT-PCR) among residences with ≥1 SARS-CoV-2 infection, and associations of household characteristics with surface RT-PCR and viable virus positivity. Of 1232 samples from 124 households, 27.8% (n = 342) were RT-PCR positive with nightstands (44.1%) and pillows (40.9%) most frequently positive. SARS-CoV-2 lineage, documented household transmission, greater number of infected persons, shorter interval between illness onset and sampling, total household symptoms, proportion of infected persons ≤12 years old, and persons exhibiting upper respiratory symptoms or diarrhea were associated with more positive surfaces. Viable virus was isolated from 0.2% (n = 3 samples from one household) of all samples. This investigation suggests that while SARS-CoV-2 on surfaces is common, fomite transmission risk in households is low.

Comparison of Home Antigen Testing With RT-PCR and Viral Culture During the Course of SARS-CoV-2 Infection.

Importance: As self-collected home antigen tests become widely available, a better understanding of their performance during the course of SARS-CoV-2 infection is needed. Objective: To evaluate the diagnostic performance of home antigen tests compared with reverse transcription-polymerase chain reaction (RT-PCR) and viral culture by days from illness onset, as well as user acceptability. Design, Setting, and Participants: This prospective cohort study was conducted from January to May 2021 in San Diego County, California, and metropolitan Denver, Colorado. The convenience sample included adults and children with RT-PCR-confirmed infection who used self-collected home antigen tests for 15 days and underwent at least 1 nasopharyngeal swab for RT-PCR, viral culture, and sequencing. Exposures: SARS-CoV-2 infection. Main Outcomes and Measures: The primary outcome was the daily sensitivity of home antigen tests to detect RT-PCR-confirmed cases. Secondary outcomes included the daily percentage of antigen test, RT-PCR, and viral culture results that were positive, and antigen test sensitivity compared with same-day RT-PCR and cultures. Antigen test use errors and acceptability were assessed for a subset of participants. Results: This study enrolled 225 persons with RT-PCR-confirmed infection (median [range] age, 29 [1-83] years; 117 female participants [52%]; 10 [4%] Asian, 6 [3%] Black or African American, 50 [22%] Hispanic or Latino, 3 [1%] Native Hawaiian or Other Pacific Islander, 145 [64%] White, and 11 [5%] multiracial individuals) who completed 3044 antigen tests and 642 nasopharyngeal swabs. Antigen test sensitivity was 50% (95% CI, 45%-55%) during the infectious period, 64% (95% CI, 56%-70%) compared with same-day RT-PCR, and 84% (95% CI, 75%-90%) compared with same-day cultures. Antigen test sensitivity peaked 4 days after illness onset at 77% (95% CI, 69%-83%). Antigen test sensitivity improved with a second antigen test 1 to 2 days later, particularly early in the infection. Six days after illness onset, antigen test result positivity was 61% (95% CI, 53%-68%). Almost all (216 [96%]) surveyed individuals reported that they would be more likely to get tested for SARS-CoV-2 infection if home antigen tests were available over the counter. Conclusions and Relevance: The results of this cohort study of home antigen tests suggest that sensitivity for SARS-CoV-2 was moderate compared with RT-PCR and high compared with viral culture. The results also suggest that symptomatic individuals with an initial negative home antigen test result for SARS-CoV-2 infection should test again 1 to 2 days later because test sensitivity peaked several days after illness onset and improved with repeated testing.

SARS-CoV-2 infection risk among vaccinated and unvaccinated household members during the Alpha variant surge - Denver, Colorado, and San Diego, California, January-April 2021.

BACKGROUND: COVID-19 vaccination reduces SARS-CoV-2 infection and transmission. However, evidence is emerging on the degree of protection across variants and in high-transmission settings. To better understand the protection afforded by vaccination specifically in a high-transmission setting, we examined household transmission of SARS-CoV-2 during a period of high community incidence with predominant SARS-CoV-2 B.1.1.7 (Alpha) variant, among vaccinated and unvaccinated contacts. METHODS: We conducted a household transmission investigation in San Diego County, California, and Denver, Colorado, during January-April 2021. Households were enrolled if they had at least one person with documented SARS-CoV-2 infection. We collected nasopharyngeal swabs, blood, demographic information, and vaccination history from all consenting household members. We compared infection risks (IRs), RT-PCR cycle threshold values, SARS-CoV-2 culture results, and antibody statuses among vaccinated and unvaccinated household contacts. RESULTS: We enrolled 493 individuals from 138 households. The SARS-CoV-2 variant was identified from 121/138 households (88%). The most common variants were Alpha (75/121, 62%) and Epsilon (19/121, 16%). There were no households with discordant lineages among household members. One fully vaccinated secondary case was symptomatic (13%); the other 5 were asymptomatic (87%). Among unvaccinated secondary cases, 105/108 (97%) were symptomatic. Among 127 households with a single primary case, the IR for household contacts was 45% (146/322; 95% Confidence Interval [CI] 40-51%). The observed IR was higher in unvaccinated (130/257, 49%, 95% CI 45-57%) than fully vaccinated contacts (6/26, 23%, 95% CI 11-42%). A lower proportion of households with a fully vaccinated primary case had secondary cases (1/5, 20%) than households with an unvaccinated primary case (66/108, 62%). CONCLUSIONS: Although SARS-CoV-2 infections in vaccinated household contacts were reported in this high transmission setting, full vaccination protected against SARS-CoV-2 infection. These findings further support the protective effect of COVID-19 vaccination and highlight the need for ongoing vaccination among eligible persons.