RESUMEN
BackgroundUnderstanding the symptomatology and accuracy of clinical case definitions for COVID-19 in the community is important for the initiation of Test, Trace and Isolate (TTI) and may, in future, be important for early prescription of antivirals. MethodsVirus Watch is a large community cohort with prospective daily recording of a wide range of symptoms and self-reporting of swab results (mainly undertaken through the UK TTI system). We compared frequency, severity, timing, and duration of symptoms in test positive and test negative cases. We compared the test performance of the current UK case definition used by TTI (any one of: new continuous cough, high temperature, or loss of or altered sense of smell or taste) with a wider definition that also included muscle aches, chills, headache, or loss of appetite. FindingsWe included results from 8213 swabbed illnesses, 944 of which tested positive for SARS-CoV-2. All symptoms were more common in test positive than test negative illnesses and symptoms were also more severe and of longer duration. Common symptoms such as cough, headache, fatigue, muscle aches, and loss of appetite occurred early in the course of illness but were also very common in test-negative illnesses. In contrast, high temperature and loss of or altered sense of smell or taste were less frequently identified in swab positive illnesses but were markedly more common than in swab negative illnesses. The current UK definition had a sensitivity and specificity of 81% and 47% respectively for symptomatic COVID-19 compared to 93% and 26% for the broader definition. On average, cases met the broader case definition 0.3 days earlier than the current definition. 1.7-fold more illnesses met the broader definition than the current case definition. InterpretationCOVID-19 is difficult to distinguish from other respiratory infections and common ailments on the basis of symptoms. Broadening the list of symptoms used to encourage engagement with TTI could moderately increase the number of infections identified and shorten delays to isolation, but with a large increase in the number of tests needed and the number of unwell individuals and contacts who are advised to self-isolate whilst awaiting results, and subsequently test negative for SARS-CoV-2.
RESUMEN
BackgroundHousehold overcrowding is associated with increased risk of infectious diseases across contexts and countries. Limited data exist linking household overcrowding and risk of COVID-19. We used data collected from the Virus Watch cohort to examine the association between overcrowded households and SARS-CoV-2. MethodsThe Virus Watch study is a household community cohort of acute respiratory infections in England & Wales that began recruitment in June 2020. We calculated the persons per room for each household and classified accommodation as overcrowded when the number of rooms{square}was fewer than the number of people. We considered two primary outcomes - PCR-confirmed positive SARS-CoV-2 antigen tests and laboratory confirmed SARS-CoV-2 antibodies (Roche Elecsys anti-N total immunoglobulin assay). We used mixed effects logistic regression models that accounted for household structure to estimate the association between household overcrowding and SARS-CoV-2 infection. ResultsThe proportion of participants with a positive SARS-CoV-2 PCR result was highest in the overcrowded group (6.6%; 73/1,102) and lowest in the under-occupied group (2.9%; 682/23,219). In a mixed effects logistic regression model that included age, sex, ethnicity, household income and geographical region, we found strong evidence of an increased odds of having a positive PCR SARS-CoV-2 antigen result (Odds Ratio 3.72; 95% CI: 1.92, 7.13; p-value < 0.001) and increased odds of having a positive SARS-CoV-2 antibody result in individuals living in overcrowded houses (2.96; 95% CI: 1.13, 7.74; p-value =0.027) compared to people living in under-occupied houses. The proportion of variation at the household level was 9.91% and 9.97% in the PCR and antibody models respectively. DiscussionPublic health interventions to prevent and stop the spread of SARS-CoV-2 should consider the much greater risk of infection for people living in overcrowded households and pay greater attention to reducing household transmission. There is an urgent need to better recognise housing as a leading determinant of health in the context of a pandemic and beyond.
RESUMEN
BackgroundAlthough SARS-CoV-2 infection in Healthcare Workers (HCWs) is a public health concern, there is little description of their longitudinal antibody response in the presence or absence of SARS-CoV-2 and symptoms. We followed HCWs in an acute London hospital to measure seroconversion and RNA detection at the peak of the pandemic. MethodsWe enrolled 200 patient-facing HCWs between 26 March and 8 April 2020 and collected twice-weekly self-administered nose and throat swabs, symptom data and monthly blood samples. Swabs were tested for SARS-CoV-2 by PCR, and serum for antibodies to spike protein by ELISA and flow cytometry. FindingsDuring the first month, 42/200 (21%) HCWs were PCR positive in at least one nose and throat swab. Only 8/42 HCW (19%) who were PCR positive during the study period had symptoms that met current case definition. Of 181 HCWs who provided enrollment and follow-up blood samples, 82/181 (45.3%) were seropositive. In 33 HCWs who had positive serology at baseline but were PCR negative, 32 remained PCR negative. One HCW had a PCR positive swab six days after enrollment, likely representing waning infection. ConclusionThe high seropositivity and RNA detection in these front-line HCWs brings policies to protect staff and patients into acute focus. Our findings have implications for planning for the second wave and for vaccination campaigns in similar settings. The evidence of asymptomatic SARS-CoV-2 infection indicates that asymptomatic HCW surveillance is essential, while our study sets the foundations to answer pertinent questions around the duration of protective immune response and the risk of re-infection.
