Ongoing symptoms and functional impairment 12 weeks after testing positive to SARS-CoV-2 or influenza in Australia: an observational cohort study (preprint)

Objective In a highly vaccinated Australian population we aimed to compare ongoing symptoms and functional impairment 12 weeks after PCR-confirmed COVID-19 infection with PCR-confirmed influenza infection. Methods and Analysis The study commenced upon a positive PCR test for either COVID-19 or influenza in June 2022 during concurrent waves of both viruses. Participants were followed up 12 weeks later in September 2022 and self-reported ongoing symptoms and functional impairment. We conducted a multivariate logistic regression analysis, controlling for age, sex, First Nations status, vaccination status, and socio-economic profile. Results There were 2 195 and 951 participants in the COVID-19 and influenza-positive cohorts respectively. After controlling for potential predictor variables, we found no evidence to suggest adults with COVID-19 were more likely to have ongoing symptoms (21.4% vs 23.0%, aOR 1.18; 95% CI 0.92-1.50) or moderate to severe functional impairment (4.1% vs 4.4%, OR 0.81; 95% CI 0.55-1.20) at 12 weeks after their diagnosis than adults who had influenza. Conclusions In a highly vaccinated population exposed to the SARS-CoV-2 omicron variant, long COVID may manifest as a post-viral syndrome of no greater severity than seasonal influenza but differing in terms of the volume of people affected and the potential impact on health systems. This study underscores the importance of long COVID research featuring an appropriate comparator group.

Estimates of the rate of infection and asymptomatic COVID-19 disease in a population sample from SE England (preprint)

BackgroundUnderstanding of the true asymptomatic rate of infection of SARS-CoV-2 is currently limited, as is understanding of the population-based seroprevalence after the first wave of COVID-19 within the UK. The majority of data thus far come from hospitalised patients, with little focus on general population cases, or their symptoms. MethodsWe undertook enzyme linked immunosorbent assay characterisation of IgM and IgG responses against SARS-CoV-2 spike glycoprotein and nucleocapsid protein of 431 unselected general-population participants of the TwinsUK cohort from South-East England, aged 19-86 (median age 48; 85% female). 382 participants completed prospective logging of 14 COVID-19 related symptoms via the COVID Symptom Study App, allowing consideration of serology alongside individual symptoms, and a predictive algorithm for estimated COVID-19 previously modelled on PCR positive individuals from a dataset of over 2 million. FindingsWe demonstrated a seroprevalence of 12% (51participants of 431). Of 48 seropositive individuals with full symptom data, nine (19%) were fully asymptomatic, and 16 (27%) were asymptomatic for core COVID-19 symptoms: fever, cough or anosmia. Specificity of anosmia for seropositivity was 95%, compared to 88% for fever cough and anosmia combined. 34 individuals in the cohort were predicted to be Covid-19 positive using the App algorithm, and of those, 18 (52%) were seropositive. InterpretationSeroprevalence amongst adults from London and South-East England was 12%, and 19% of seropositive individuals with prospective symptom logging were fully asymptomatic throughout the study. Anosmia demonstrated the highest symptom specificity for SARS-CoV-2 antibody response. FundingNIHR BRC, CDRF, ZOE global LTD, RST-UKRI/MRC