Long-term complications after coronavirus disease 2019 (COVID-19) are common in hospitalized patients, but the spectrum of symptoms in milder cases needs further investigation. We conducted a long-term follow-up in a prospective cohort study of 312 patients—247 home-isolated and 65 hospitalized—comprising 82% of total cases in Bergen during the first pandemic wave in Norway. At 6 months, 61% (189/312) of all patients had persistent symptoms, which were independently associated with severity of initial illness, increased convalescent antibody titers and pre-existing chronic lung disease. We found that 52% (32/61) of home-isolated young adults, aged 16–30 years, had symptoms at 6 months, including loss of taste and/or smell (28%, 17/61), fatigue (21%, 13/61), dyspnea (13%, 8/61), impaired concentration (13%, 8/61) and memory problems (11%, 7/61). Our findings that young, home-isolated adults with mild COVID-19 are at risk of long-lasting dyspnea and cognitive symptoms highlight the importance of infection control measures, such as vaccination.

Background Households studies reflect the natural spread of SARS-CoV-2 in immunologically naive populations with limited preventive measures to control transmission. We hypothesise that seropositivity provides more accurate household attack rates than RT-PCR. Here, we investigated the importance of age in household transmission dynamics. Methods We enroled 112 households (291 participants) in a case-ascertained study in Bergen, Norway from 28th February to 4th April 2020, collecting demographic and clinical data from index patients and household members. SARS-CoV-2-specific antibodies were measured in sera collected 6–8 weeks after index patient nasopharyngeal testing to define household attack rates. Findings The overall attack rate was 45% (95% CI 38–53) assessed by serology, and 47% when also including seronegative RT-PCR positives. Serology identified a higher number of infected household members than RT-PCR. Attack rates were equally high in children (48%) and young adults (42%). The attack rate was 16% in asymptomatic household members and 42% in RT-PCR negative contacts. Older adults had higher antibody titres than younger adults. The risk of household transmission was higher when the index patient had fever (aOR 3.31 [95% CI 1.52–7.24]; p = 0.003) or dyspnoea (aOR 2.25 [95% CI 1.80–4.62]; p = 0.027) during acute illness. Interpretation Serological assays provide more sensitive and robust estimates of household attack rates than RT-PCR. Children are equally susceptible to infection as young adults. Negative RT-PCR or lack of symptoms are not sufficient to rule out infection in household members. Funding Helse Vest (F-11628), Trond Mohn Foundation (TMS2020TMT05).

Background The burden and duration of persistent symptoms after non-severe COVID-19 remains uncertain. This study aimed to assess post-infection symptom trajectories in home-isolated COVID-19 cases compared to age- and time-period matched seronegative controls, and investigate immunological correlates of long COVID. Methods A prospective case-control study conducted between February 28th and April 4th 2020 included home-isolated COVID-19 cases followed for 12 (n = 233) to 18 (n = 149) months, and 189 age-matched SARS-CoV-2 naive controls. We collected clinical data at baseline, 6, 12 and 18 months post-infection, and blood samples at 2, 4, 6 and 12 months for analysis of SARS-CoV-2 specific humoral and cellular responses. Results Overall, 46% (108/233) had persisting symptoms 12 months after COVID-19. Compared to controls, adult cases had a high risk of fatigue (27% excess risk, gender and comorbidity adjusted odds ratio [aOR] 5.86, 95% confidence interval [CI]3.27-10.5), memory problems (21% excess risk, aOR 7.42, CI 3.51-15.67), concentration problems (20% excess risk, aOR 8.88, CI 3.88-20.35), and dyspnea (10% excess risk, aOR 2.66, CI 1.22-5.79). The prevalence of memory problems increased overall from 6 to 18 months (excess risk 11.5%, CI 1.5, 21.5, p = 0.024) and among women (excess risk 18.7%, CI 4.4, 32.9, p = 0.010). Longitudinal spike IgG was significantly associated with dyspnea at 12 months. The spike-specific clonal CD4 + TCRβ depth was significantly associated with both dyspnea and number of symptoms at 12 months. Conclusions This study documents a high burden of persisting symptoms after mild COVID-19, and suggest that infection induced SARS-CoV-2 specific immune responses may influence long-term symptoms.