Rates of asymptomatic respiratory virus infection across age groups

Galanti, Marta; Birger, Ruthie; Ud‐Dean, Minhaz; Filip, Ioan; Morita, Hiromichi; Comito, Devon; Anthony, Simon J.; Freyer, Greg A.; Ibrahim, Sadiat; Lane, Benjamin; Matienzo, Nelsa; Ligon, Chanel; Rabadán, Raúl; Shittu, Atinuke; Tagne, Eudosie; Shaman, Jeffrey

doi:10.1017/s0950268819000505

Cited by 61 publications

(70 citation statements)

References 21 publications

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“…Among the many pathogens that cause respiratory symptoms, some (like influenza and HMPV) have been shown to be responsible for more severe infections. 4 Our observations here support the hypothesis that the distribution of viral prevalence derived from healthcare-based data is skewed toward more severe pathogens, possibly leading to mis-estimation of the prevalence of infections in the broader population. The findings, validated through scaling using Bayes' theorem, showed that viruses producing more severe symptoms (influenza, HMPV) were overrepresented in the pediatric ED, whereas others, like coronavirus, were substantially underestimated in prevalence.…”

Section: Discussionsupporting

confidence: 80%

Active surveillance documents rates of clinical care seeking due to respiratory illness

Galanti

Comito

Ligon

et al. 2020

Influenza Resp Viruses

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Background: Respiratory viral infections are a leading cause of disease worldwide.However, the overall community prevalence of infections has not been properly assessed, as standard surveillance is typically acquired passively among individuals seeking clinical care. Methods:We conducted a prospective cohort study in which participants provided daily diaries and weekly nasopharyngeal specimens that were tested for respiratory viruses. These data were used to analyze healthcare seeking behavior, compared with cross-sectional ED data and NYC surveillance reports, and used to evaluate biases of medically attended ILI as signal for population respiratory disease and infection. Results:The likelihood of seeking medical attention was virus-dependent: higher for influenza and metapneumovirus (19%-20%), lower for coronavirus and RSV (4%), and 71% of individuals with self-reported ILI did not seek care and half of medically attended symptomatic manifestations did not meet the criteria for ILI. Only 5% of cohort respiratory virus infections and 21% of influenza infections were medically attended and classifiable as ILI. We estimated 1 ILI event per person/year but multiple respiratory infections per year. Conclusion:Standard, healthcare-based respiratory surveillance has multiple limitations. Specifically, ILI is an incomplete metric for quantifying respiratory disease, viral respiratory infection, and influenza infection. The prevalence of respiratory viruses, as reported by standard, healthcare-based surveillance, is skewed toward viruses producing more severe symptoms. Active, longitudinal studies are a helpful supplement to standard surveillance, can improve understanding of the overall circulation and burden of respiratory viruses, and can aid development of more robust measures for controlling the spread of these pathogens.

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Section: Discussionsupporting

confidence: 80%

Active surveillance documents rates of clinical care seeking due to respiratory illness

Galanti

Comito

Ligon

et al. 2020

Influenza Resp Viruses

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“…We refer to both asymptomatic and paucisymptomatic infections as 'subclinical infections'-which are more likely to remain undetected than clinical cases-and refer to the age-specific proportion of infections resulting in clinical symptoms as the 'clinical fraction' . Age-dependent variation in severity has been observed for other respiratory virus infections 17 , including SARS 17,18 . For COVID-19, there are strong indications of age dependence in severity 5,19 and mortality 18,19 among those cases that are reported, which could extend more generally to age-dependent severity and likelihood of clinically reportable symptoms upon infection.…”

mentioning

confidence: 97%

Age-dependent effects in the transmission and control of COVID-19 epidemics

Davies

Klepac

Liu

et al. 2020

Nat Med

1,716

1,746

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The COVID-19 pandemic has shown a markedly low proportion of cases among children 1-4. Age disparities in observed cases could be explained by children having lower susceptibility to infection, lower propensity to show clinical symptoms or both. We evaluate these possibilities by fitting an age-structured mathematical model to epidemic data from China, Italy, Japan, Singapore, Canada and South Korea. We estimate that susceptibility to infection in individuals under 20 years of age is approximately half that of adults aged over 20 years, and that clinical symptoms manifest in 21% (95% credible interval: 12-31%) of infections in 10-to 19-year-olds, rising to 69% (57-82%) of infections in people aged over 70 years. Accordingly, we find that interventions aimed at children might have a relatively small impact on reducing SARS-CoV-2 transmission, particularly if the transmissibility of subclinical infections is low. Our age-specific clinical fraction and susceptibility estimates have implications for the expected global burden of COVID-19, as a result of demographic differences across settings. In countries with younger population structures-such as many low-income countries-the expected per capita incidence of clinical cases would be lower than in countries with older population structures, although it is likely that comorbidities in low-income countries will also influence disease severity. Without effective control measures, regions with relatively older populations could see disproportionally more cases of COVID-19, particularly in the later stages of an unmitigated epidemic. COVID-19 shows an increased number of cases and a greater risk of severe disease with increasing age 5,6 , a feature shared with the 2003 SARS epidemics 7. This age gradient in reported cases, which has been observed from the earliest stages of the pandemic 1 , could result from children having decreased susceptibility to infection, a lower probability of showing disease on infection or a combination of both, compared with adults. Understanding the role of age in transmission and disease severity is critical for determining the likely impact of social-distancing interventions on SARS-CoV-2 transmission 8 , especially those aimed at schools, and for estimating the expected global disease burden. Here, we disentangle the relative contributions of three potential drivers of the observed distribution of clinical cases by age. We present a summary of the main findings, limitations and implications of this work in Table 1. First, age-varying susceptibility to infection by SARS-CoV-2, where children are less susceptible than adults to becoming infected on contact with an infectious person, would reduce cases among children. Decreased susceptibility could result from immune for predicted global burden and the effectiveness of control interventions. This question must be resolved to effectively forecast and control COVID-19 epidemics.

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“…Figure 3 shows the total symptom score associated with any 183 coronavirus infection for infections grouped by family cluster. Infection with these viruses generally produces mild and even asymptomatic infection [10]. 194…”

mentioning

confidence: 99%