Is there Asymptomatic Spread of COVID-19?

Are Hospitals Spreading the Virus? 6 April 2020.  Updated 13 March 2021

Eminent doc: Media censored COVID-19 early treatment options that could have reduced fatalities by 85%. Dr. Peter McCullough also explained that given an 80% level of herd immunity, broad vaccination has ‘no scientific, clinical or safety rationale.’ Apr 8, 2021. ...Addressing the broad “misinformation” of asymptomatic transfer of COVID-19, which has supported the need for lockdowns due to the notion that the virus can be unintentionally spread by infectious, asymptomatic people, the medical professor said, “One of the mistakes I heard today as a rationale for vaccination is asymptomatic spread. And I want to be very clear about this: My opinion is there is a low degree, if any, of asymptomatic spread. Sick person gives it to sick person. The Chinese have published a study … [of] 11 million people. They tried to find [evidence of] asymptomatic spread. You can't find it. And that's been, you know, one of important pieces of misinformation.”

What proportion of people with COVID-19 do not get symptoms? April 2021. The actual number of people who get infected with the SARS-Cov-2 virus who have no symptoms is approximately 1 in 19.
 
This one study finding pre-symptomatic spread was published by the US CDC, not in a peer-reviewed journal, used only PCR tests to confirm cases, many cases of which did not  exhibit cough symptom and some cases were married couples, so is not wholly convincing: Presymptomatic Transmission of SARS-CoV-2 — Singapore, January 23–March 16, 2020

The Diamond Princess Told Us About Pre-Existing Immunity, Asymptomatic Infection and the Infection Fatality Rate. Why Were Those Lessons Ignored? March 2021

Giant Study Disproves Myth Of Asymptomatic COVID Spread December 2020. “A total of 1,174 close contacts of the asymptomatic positive cases were traced, and they all tested negative for the COVID-19,” the study concluded. Both the asymptomatic patients and their contacts were placed in isolation for a period of no less than two weeks and the results remained the same. “None of detected positive cases or their close contacts became symptomatic or newly confirmed with COVID-19 during the isolation period,” the study found. Post-lockdown SARS-CoV-2 nucleic acid screening in nearly ten million residents of Wuhan, China. November 2020.

Household Transmission of SARS-CoV-2A Systematic Review and Meta-analysis. December 14, 2020. Zachary J. Madewell, PhD1; Yang Yang, PhD1; Ira M. Longini Jr, PhD1; et al The findings of this study suggest that given that individuals with suspected or confirmed infections are being referred to isolate at home, households will continue to be a significant venue for transmission of SARS-CoV-2.

Letter to the New England Journal of Medicine Open Schools, Covid-19, and Child and Teacher Morbidity in Sweden. By  Jonas F. Ludvigsson, M.D., Ph.D., Lars Engerström, M.D., Ph.D., Charlotta Nordenhäll, M.D., Ph.D., Emma Larsson, M.D., Ph.D. Despite Sweden’s having kept schools and preschools open, we found a low incidence of severe Covid-19 among schoolchildren and children of preschool age during the SARS-CoV-2 pandemic. Among the 1.95 million children who were 1 to 16 years of age, 15 children had Covid-19, MIS-C, or both conditions and were admitted to an ICU, which is equal to 1 child in 130,000.

Risk of Asymptomatic Spread Minimal. Variants Over-Hyped. Masks Pointless. An Interview With Professor Jay Bhattacharya  March 2021

New research finds no evidence that schools are playing a significant role in driving spread of the Covid-19 virus in the community  Research led by epidemiologists at the University of Warwick has found that there is no significant evidence that schools are playing a significant role in driving the spread of the Covid-19 disease in the community, particularly in primary schools.  However, careful continued monitoring may be required as schools re-open to stay well informed about the effect they have upon community incidence.

No evidence of secondary transmission of COVID-19 from children attending school in Ireland   2020 Laura Heavey, Geraldine Casey , Ciara Kelly , David Kelly , Geraldine McDarby Contact tracing over 10,000 contacts found no transmission by children.

Incidence and Secondary Transmission of SARS-CoV-2 Infections in Schools By Kanecia O. Zimmerman, Ibukunoluwa C. Akinboyo, M. Alan Brookhart, Angelique E. Boutzoukas, Kathleen McGann, Michael J. Smith, Gabriela Maradiaga Panayotti, Sarah C. Armstrong, Helen Bristow, Donna Parker, Sabrina Zadrozny, David J. Weber and Daniel K. Benjamin; for The ABC Science Collaborative. Pediatrics January 2021, e2020048090; DOI: https://doi.org/10.1542/peds.2020-048090    Studied 90,000 students and staff. No instances of child-to-adult transmission of SARS-COV-2 virus.

Relation of severe COVID-19 in Scotland to transmission-related factors and risk conditions eligible for shielding support: REACT-SCOT case-control study. March 2021. In both the shielded (the “clinically extremely vulnerable” – about 3% of the population) and the general population, the risk of severe COVID-19 (defined as requiring intensive care or dying) increased with the number of adults but decreased with the number of school-age children in the household. Severe COVID-19 was strongly associated with recent exposure to hospital... (Together with the high risk found in nursing homes, almost all severe COVID-19 cases are from hospitals or occur in elderly care homes. This helps to explain why lockdowns, despite the intuitive logic of keeping people apart, are consistently found to have little or no relationship to mortality or infection rates.)

Asymptomatic cases may be of great value in containing the pandemic August 2020 

The following table is a summary analysis of groups who were together for long periods without any ability to distance and shared the same kitchen and ventilation systems.  Thus, the prevalence of COVID-19 in these groups can give us an idea of the share of the population prone to getting COVID symptoms.  Overall, it seems that slightly less than 8% of the population were susceptible to symptomatic COVID-19. However the rate is closer to 60% for nursing home facility residents.

Data from Groups Exposed to SARS-COV-2 with No Distancing Possible
Data from Groups Exposed to SARS-COV-2 with No Distancing Possible

Video: W.H.O. Says Covid-19 Asymptomatic Transmission Is ‘Very Rare’ December 2020.

Sweden's health agency says open schools did not spur pandemic spread among children. By Helena Soderpalm

Has the Evidence of Asymptomatic Spread of COVID-19 been Significantly Overstated? December 2020. by Dr Clare Craig FRCPath and Jonathan Engler MBChB LLB Abstract: Evidence of transmission of SARS-CoV-2 from patients who remain asymptomatic (as opposed to pre-symptomatic) is found in a body of numerous meta-analyses. Evidence of asymptomatic transmission has been based on only a handful of instances which themselves are questionable. The existence of transmission of SARS-CoV-2 from asymptomatic individuals has become an accepted truth but the evidence for this phenomenon being anything other than mistaken interpretation of false positive test results is weak. Examination of the underlying data from the most frequently-cited such meta-analyses reveals that the conclusions are based on a surprisingly small number of cases (six in total globally) and, moreover, the possibility that they are all coincidental contacts with false positive results cannot be ruled out. Transmission which is pre-symptomatic is rare and represents a negligible risk to the population. It is questionable therefore whether any of the extensive testing, tracing, isolation and lockdown policies have delivered any worthwhile benefit over and above strategies which seek to advise symptomatic individuals to self-isolate.

‘No evidence’ that asymptomatic Covid-19 cases were infectious, analysis of post-lockdown Wuhan concludes   November 2020   This paper analyzed the results of a massive post-lockdown Covid-19 testing drive that included nearly every eligible resident of Wuhan, China has found no evidence that positive cases without symptoms spread the disease. 

Post-lockdown SARS-CoV-2 nucleic acid screening in nearly ten million residents of Wuhan, China By Shiyi CaoYong GanChao WangMax BachmannShanbo WeiJie GongYuchai HuangTiantian WangLiqing LiKai LuHeng JiangYanhong GongHongbin XuXin ShenQingfeng TianChuanzhu LvFujian SongXiaoxv YinZuxun Lu.   https://pubmed.ncbi.nlm.nih.gov/33219229/ 2020 November  Abstract: Stringent COVID-19 control measures were imposed in Wuhan between January 23 and April 8, 2020. Estimates of the prevalence of infection following the release of restrictions could inform post-lockdown pandemic management. Here, we describe a city-wide SARS-CoV-2 nucleic acid screening programme between May 14 and June 1, 2020 in Wuhan. All city residents aged six years or older were eligible and 9,899,828 (92.9%) participated. No new symptomatic cases and 300 asymptomatic cases (detection rate 0.303/10,000, 95% CI 0.270-0.339/10,000) were identified. There were no positive tests amongst 1,174 close contacts of asymptomatic cases. 107 of 34,424 previously recovered COVID-19 patients tested positive again (re-positive rate 0.31%, 95% CI 0.423-0.574%). The prevalence of SARS-CoV-2 infection in Wuhan was therefore very low five to eight weeks after the end of lockdown.

Asymptomatic Cases are *not* infectious   https://www.nature.com/articles/s41467-020-19802-w November 2020

What the data say about asymptomatic COVID infections People without symptoms can pass on the virus, but estimating their contribution to outbreaks is challenging.

Asymptomatic infected persons do not tend to spread infection.  A Study on Infectivity of Asymptomatic SARS-CoV-2 Carriers.  Ming Gao 1, Lihui Yang 2, Xuefu Chen 3, Yiyu Deng 4, Shifang Yang 5, Hanyi Xu 5, Zixing Chen 5, Xinglin Gao 5

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7219423/

COVID-19 in primary schools: no significant transmission among children or from students to teachers

July 2020.  Re-opening schools in Sweden & Finland did not worsen outbreak

How CNN Deceives About Asymptomatic Transmission of SARS-CoV-2 by Jeremy R. Hammond. July 2020. On August 20, 2020 US media reported that [all] children are "silent spreaders of COVID ", citing a study of 49 "Children ages 0-22 years with suspected severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection presenting to urgent care clinics or being hospitalized for confirmed/suspected SARS-CoV-2 infection".  61.7% of these sickest Massachusetts’ children are over the age of 10 and most have prior medical conditions. These are not normal healthy asymptomatic children. These children’s viral levels were compared to some of the sickest, many intubated, adult patients whose cytokine storms had eliminated the virus from their bodies and were deeply ill.  The fallacious study is posted: https://www.jpeds.com/article/S0022-3476(20)31023-4/fulltext 

Schools Aren’t Super-Spreaders.  Fears from the summer appear to have been overblown. October 2020 By Emily Oster Economist at Brown University

Epidemiologist: "Social Distancing" Does Not Stop Spread of COVID-19, Only Vulnerable Should Shelter 

Sharing a household with children and risk of COVID-19: a study of over 300,000 adults living in healthcare worker households in Scotland

Rachael Wood, Emma C Thomson, Robert Galbraith, Ciara Gribben, David Caldwell, Jennifer Bishop, Martin Reid,  Anoop Shah, Kate Templeton, David Goldberg, Chris Robertson, Sharon Hutchinson, Helen M Colhoun, Paul M McKeigue, David McAllister