A larger proportion of people with BA.2 reported that their symptoms had affected their ability to carry out day-to-day activities ‘a lot’ (17.6% ) compared with those infected with BA.1 (10.7% ) or Delta (10.5%, ) (Supplementary Table 2).Īll symptoms were positively associated with swab positivity for all variants (Fig. Those infected with BA.2 reported an average of 6.0 (95% CI 5.8,6.2) symptoms in the week prior to PCR testing, compared with 2.70 (2.6,2.8), 3.4 (3.2,3.6), 4.6 (4.4,4.9) and 4.6 (4.5,4.8) for wild-type, Alpha, Delta and BA.1 respectively (Supplementary Table 2). Background prevalence of symptoms was also highest during January–March 2022, when Omicron dominated: 21.9%, of all respondents reported one or more symptoms, compared with 13.5% during the wild-type period (Supplementary Table 1). The proportion of swab positive individuals reporting any of 26 symptoms (symptoms listed in Supplementary Table 1) was highest in those infected with BA.2 (75.9%, compared with 70.0% in those with BA.1, 63.8% in those with Delta, 54.7%, in those with Alpha and 45.0% in those with wild-type) (Table S2). Here, we use regression modelling and variable selection models in the large community-based REal-time Assessment of Community Transmission −1 (REACT-1) study that was in the field approximately monthly from to 31 March 2022 to i) describe the symptom profiles of the main variants of SARS-CoV-2 that have been dominant in England and worldwide over this period, namely wild-type, Alpha, Delta and Omicron BA.1 and BA.2, and ii) identify the symptoms that are most predictive of high viral load, and hence infectiousness, for each variant. Identifying individuals who are more likely to be (i) infected, and (ii) infectious on the basis of symptom profile would have clinical value as governments move away from mass testing programmes and mandatory isolation measures. The relationship between symptom profile and cycle threshold (Ct) value from PCR testing (an established proxy for viral load 8, 9, 10, which in turn correlates with infectiousness 11, 12) has yet to be fully investigated. Further studies have indicated that symptom profiles may differ between variants of SARS-CoV-2 5, 6, 7. Previous community-based studies have assessed the degree to which symptom data can predict polymerase chain reaction (PCR) positivity for SARS-CoV-2, and have used variable selection and ranking techniques to identify the most important (set of) symptoms for case identification 2, 3, 4. A meta-analysis of studies from the first wave of the pandemic identified 30 symptoms reported in multiple studies 1, including common influenza-like symptoms (cough, fever, myalgia/fatigue, headache, sputum production), and less common but more specific symptoms including change or loss of sense of smell or taste.
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