Assessing the asymptomatic proportion of SARS-CoV-2 infection with age in China before mass vaccination

Article Multidisciplinary Sciences

Assessing the asymptomatic proportion of SARS-CoV-2 infection with age in China before mass vaccination

Zengmiao Wang et al.

Summary: The proportion of asymptomatic infections decreases with age, with children and young adults more likely to have asymptomatic infections. Surveillance strategies for SARS-CoV-2 should take age into account.

JOURNAL OF THE ROYAL SOCIETY INTERFACE (2022)

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Review Immunology

A systematic review of asymptomatic infections with COVID-19

Zhiru Gao et al.

Summary: Since the outbreak of COVID-19 at the end of December 2019, it has caused significant harm and challenges to over 200 countries and regions worldwide. Many patients with COVID-19 are asymptomatic or have only mild symptoms, yet they can still spread the virus, making screening for asymptomatic infections difficult and complicating national prevention and control efforts.

JOURNAL OF MICROBIOLOGY IMMUNOLOGY AND INFECTION (2021)

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Article Virology

Transmission dynamics of SARS-CoV-2 within families with children in Greece: A study of 23 clusters

Helena C. Maltezou et al.

Summary: The study on the transmission dynamics of SARS-CoV-2 within families with children in Greece found that adults were more likely to transmit the infection to children, while children were more likely to have asymptomatic infections. Adults were at a higher risk of developing severe clinical courses with moderate viral loads, while children were more likely to have mild courses with low viral loads. Additional studies are needed to further investigate the role of viral load in these findings.

JOURNAL OF MEDICAL VIROLOGY (2021)

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Review Virology

Proportion of asymptomatic coronavirus disease 2019: A systematic review and meta-analysis

Jingjing He et al.

Summary: Approximately 15.6% of confirmed COVID-19 patients are asymptomatic. Nearly half of the patients with no symptoms at detection time will develop symptoms later. Children are likely to have a higher proportion of asymptomatic infection than adults. Asymptomatic COVID-19 patients could have abnormal laboratory and radiational manifestations, which can be used as screening strategies to identify asymptomatic infection.

JOURNAL OF MEDICAL VIROLOGY (2021)

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Review Medicine, General & Internal

The Proportion of SARS-CoV-2 Infections That Are Asymptomatic A Systematic Review

Daniel P. Oran et al.

Summary: Available data suggests that at least one third of SARS-CoV-2 infections are asymptomatic. Longitudinal studies indicate that nearly three quarters of individuals who test positive via PCR but show no symptoms at the time of testing will remain asymptomatic. Control strategies for COVID-19 need to be adjusted considering the prevalence and transmission risk of asymptomatic SARS-CoV-2 infections.

ANNALS OF INTERNAL MEDICINE (2021)

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Article Infectious Diseases

The prevalence of asymptomatic and symptomatic COVID-19 in a cohort of quarantined subjects

Manaf Al-Qahtani et al.

Summary: The study found that asymptomatic COVID-19 patients were more prevalent than symptomatic patients and may act as an infection reservoir; there was no significant difference in viral clearance time between symptomatic and asymptomatic patients in virus retesting; asymptomatic patients who tested positive had a faster viral clearance time than those who were asymptomatic upon arrival.

INTERNATIONAL JOURNAL OF INFECTIOUS DISEASES (2021)

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Article Infectious Diseases

Towards an accurate and systematic characterisation of persistently asymptomatic infection with SARS-CoV-2

Eric A. Meyerowitz et al.

Summary: The transmission of SARS-CoV-2 from asymptomatic individuals contributes to pandemic spread, but accurately estimating this proportion is hindered by methodological issues like incomplete symptom assessment and inadequate follow-up. Recommendations regarding definitions, detection, documentation, and follow-up are provided to improve the identification and evaluation of people with persistently asymptomatic SARS-CoV-2 infection and their contacts. Accurate characterization of the persistently asymptomatic fraction of infected individuals could shed light on COVID-19 pathogenesis and transmission dynamics, and inform public health responses.

LANCET INFECTIOUS DISEASES (2021)

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Article Multidisciplinary Sciences

Epidemiological characterization of symptomatic and asymptomatic COVID-19 cases and positivity in subsequent RT-PCR tests in the United Arab Emirates

Rami H. Al-Rifai et al.

Summary: The study analyzed the symptom status and related factors of the first cohort of COVID-19 cases in Abu Dhabi, UAE, finding associations between symptomatic cases and work environments as well as chronic diseases. Due to a significant proportion of asymptomatic cases, recommendations were made for isolating asymptomatic cases and raising awareness among high-risk populations.

PLOS ONE (2021)

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Article Multidisciplinary Sciences

Quantifying asymptomatic infection and transmission of COVID-19 in New York City using observed cases, serology, and testing capacity

Rahul Subramanian et al.

Summary: The study suggests that asymptomatic infections play a significant role in the spread and resurgence of COVID-19, even though it is challenging to accurately estimate their contributions due to changes in testing capacity. Even if asymptomatic infections have lower transmission rates, they still comprise a substantial portion of the force of infection along with presymptomatic cases.

PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA (2021)

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Article Infectious Diseases

Epidemiological and clinical features in patients with coronavirus disease 2019 outside of Wuhan, China: Special focus in asymptomatic patients

Ping Liu et al.

Summary: This study aimed to identify the characteristics of COVID-19 patients outside Wuhan to provide insights about prevention and treatment. The symptoms of patients with COVID-19 were relatively mild outside Wuhan, with family clusters being a notable epidemic characteristic. Special attention should be given to asymptomatic patients.

PLOS NEGLECTED TROPICAL DISEASES (2021)

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Article Medicine, General & Internal

Association of Age With Likelihood of Developing Symptoms and Critical Disease Among Close Contacts Exposed to Patients With Confirmed SARS-CoV-2 Infection in Italy

Piero Poletti et al.

Summary: In this cohort study in Italy, more than half of close contacts of confirmed SARS-CoV-2 patients tested positive for the virus, but most of them did not develop respiratory symptoms or fever. The low proportion of children and young adults who developed symptoms highlights the challenges in identifying SARS-CoV-2 infections.

JAMA NETWORK OPEN (2021)

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Article Multidisciplinary Sciences

The impact of relaxing interventions on human contact patterns and SARS-CoV-2 transmission in China

Juanjuan Zhang et al.

Summary: Nonpharmaceutical interventions have been implemented to control the spread of SARS-CoV-2 with varying intensity, timing, and impact on transmission. Post-lockdown COVID-19 dynamics are heterogeneous and difficult to interpret. Contact surveys in four Chinese cities showed that the mean number of contacts increased in the post-lockdown period compared to the lockdown period, but remained lower than pre-pandemic levels. The impact of school closures on transmission depends nonlinearly on the intensity of other activities.

SCIENCE ADVANCES (2021)

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Article Medicine, General & Internal

Efficacy and safety of an inactivated whole-virion SARS-CoV-2 vaccine (CoronaVac): interim results of a double-blind, randomised, placebo-controlled, phase 3 trial in Turkey

Mine Durusu Tanriover et al.

Summary: The study presented the interim efficacy and safety results of the CoronaVac vaccine in a phase 3 clinical trial in Turkey, demonstrating high efficacy against PCR-confirmed symptomatic COVID-19 with good safety and tolerability profile. Results showed significant differences in the frequency of any adverse events between the vaccine and placebo groups, indicating excellent protective effects of the vaccine.

LANCET (2021)

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Article Infectious Diseases

Effectiveness of BNT162b2 and ChAdOx1 nCoV-19 COVID-19 vaccination at preventing hospitalisations in people aged at least 80 years: a test-negative, case-control study

Catherine Hyams et al.

Summary: The study found that one dose of either the BNT162b2 or ChAdOx1 nCoV-19 vaccines resulted in substantial risk reductions for COVID-19-related hospitalisations in those aged over 80 years.

LANCET INFECTIOUS DISEASES (2021)

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Article Medicine, General & Internal

Effectiveness of an Inactivated SARS-CoV-2 Vaccine in Chile

Alejandro Jara et al.

Summary: A study in Chile involving 10.2 million participants assessed the effectiveness of an inactivated SARS-CoV-2 vaccine developed in China. Fully immunized individuals had vaccine effectiveness of 65.9% for preventing Covid-19 and 87.5% for preventing hospitalization, 90.3% for preventing ICU admission, and 86.3% for preventing death.

NEW ENGLAND JOURNAL OF MEDICINE (2021)

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Editorial Material Multidisciplinary Sciences

Asymptomatic infection is the pandemic's dark matter

David N. Fisman et al.

PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA (2021)

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Review Multidisciplinary Sciences

Asymptomatic SARS-CoV-2 infection: A systematic review and meta-analysis

Pratha Sah et al.

Summary: Quantification of asymptomatic infections is crucial for effective public health responses to the COVID-19 pandemic. Analyzing over 350 studies, it was estimated that 35.1% of infections never developed clinical symptoms and were truly asymptomatic. At the time of testing, 42.8% of cases showed no symptoms, including both asymptomatic and presymptomatic infections.

PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA (2021)

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Article Multidisciplinary Sciences

Estimating infectiousness throughout SARS-CoV-2 infection course

Terry C. Jones et al.

Summary: In a study of SARS-CoV-2 cases in Germany, it was found that younger subjects had lower viral loads but higher cell culture replication probabilities compared to older subjects. Additionally, 8% of subjects had viral loads above 10(9) copies per swab, with a third of them being presymptomatic, asymptomatic, or mildly symptomatic individuals with a mean age of 37.6 years. The B.1.1.7 lineage infections had a higher viral load and cell culture replication probability than non-B.1.1.7 subjects.

SCIENCE (2021)

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Article Medical Informatics

Associations between changes in population mobility in response to the COVID-19 pandemic and socioeconomic factors at the city level in China and country level worldwide: a retrospective, observational study

Yonghong Liu et al.

Summary: The reduction in intra-city movement intensity in China was stronger in cities with a higher socioeconomic index, and reductions in inter-city movement flow were associated with government control measures. At the country level, countries with higher sociodemographic and Universal Health Coverage indexes had greater reductions in population mobility following national emergency declarations.

LANCET DIGITAL HEALTH (2021)

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Article Medicine, General & Internal

Descriptive epidemiology of SARS-CoV-2 infection in Karnataka state, South India: Transmission dynamics of symptomatic vs. asymptomatic infections

Narendra Kumar et al.

Summary: The study in Karnataka state, India, found that 91% of COVID-19 cases were asymptomatic, with a higher mortality rate among middle-aged and elderly individuals with comorbidities. Symptomatic cases were identified as the main driving force in transmission dynamics during the initial phase of the pandemic.

ECLINICALMEDICINE (2021)

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Article Health Care Sciences & Services

Antibody seroprevalence in the epicenter Wuhan, Hubei, and six selected provinces after containment of the first epidemic wave of COVID-19 in China

Zhongjie Li et al.

Summary: China successfully contained the first wave of the COVID-19 epidemic, as evidenced by low overall infection rates and predominantly asymptomatic cases of SARS-CoV-2 infection revealed in serological surveys.

LANCET REGIONAL HEALTH-WESTERN PACIFIC (2021)

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Letter Medicine, General & Internal