Asymptomatic spread of coronavirus is ‘very rare,’ WHO says.
World Health Organization officials on Tuesday walked back the comments below that were made on Monday after drawing criticism from epidemiologists across the world. Dr. Maria Van Kerkhove, head of the WHO’s emerging diseases and zoonosis unit, said Tuesday that asymptomatic spread is a “really complex question” and much is still unknown. “We don’t actually have that answer yet,” she said.
There is still no evidence to show that people positive for the coronavirus disease (COVID-19) but do not manifest symptoms can infect others, Health Secretary Francisco Duque III said Wednesday as he quoted the World Health Organization (WHO).
A study on infectivity of asymptomatic SARS-CoV-2 carriers
The median contact time for patients was four days and that for family members was five days. Cardiovascular disease accounted for 25% among original diseases of patients. Apart from hospital staffs, both patients and family members were isolated medically. During the quarantine, seven patients plus one family member appeared new respiratory symptoms, where fever was the most common one. The blood counts in most contacts were within a normal range. All CT images showed no sign of COVID-19 infection. No severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections was detected in 455 contacts by nucleic acid test.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7219423/
‘No evidence’ that asymptomatic Covid-19 cases were infectious, analysis of post-lockdown Wuhan concludes
A paper that 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.
https://www.rt.com/news/507402-wuhan-asymptomatic-cases-coronavirus-study/
Post-lockdown SARS-CoV-2 nucleic acid screening in nearly ten million residents of Wuhan, China
https://www.nature.com/articles/s41467-020-19802-w
University of Florida researchers find no asymptomatic or presymptomatic spread
Four researchers from the University of Florida Department of Biostatistics co-authored a study published online by the Journal of the American Medical Association. They performed a meta-analysis of 54 studies looking at the household secondary attack rate of SARS-CoV-2. According to the CDC, the secondary attack rate is the number of new cases among contacts divided by the total number of contacts.
The researchers confirmed that SARS-CoV-2 is more contagious than other coronaviruses, with a secondary attack rate of 16.6% (95% CI 14.0%-19.3%) compared to 7.5% (95%CI 4.8%-10.7%) for SARS-CoV and 4.7% (95%CI, 0.9%-10.7%) for MERS-CoV.
Their findings also confirmed the attack rate is higher to adult contacts compared to child contacts and to spouses compared to other family members.
In Report Affirming Nearly No Transmission In Schools, CDC Slips In Shocking Data About Asymptomatic Spread
The U.S. Centers for Disease Control slipped in a shocking piece of evidence in a recent report on low in-school COVID-19 transmission that severely undercuts the rationale for most COVID restrictions, including lockdowns.
The Jan. 29 report’s conclusion seems to fit the pro-mask narrative, of course: “Schools might be able to safely open with appropriate mitigation efforts [such as masking and not allowing student cohorts to mix] in place.” In the 17 rural Wisconsin schools surveyed, only seven cases were linked to in-school transmission out of 4,876 pupils, and no staff members were infected at school during the study period.
While the report spends ample time explaining the mitigation strategies employed in the schools and the high reported mask compliance (92%) among students, the authors later discuss something you probably have not seen in any of the mainstream media’s coverage of this report:
“Children might be more likely to be asymptomatic carriers of COVID-19 than are adults…This apparent lack of transmission [in schools] is consistent with recent research (5), which found an asymptomatic attack rate of only 0.7% within households and a lower rate of transmission from children than from adults. However, this study was unable to rule out asymptomatic transmission within the school setting because surveillance testing was not conducted” (emphasis added).
The “recent research” the study authors cite is a meta-analysis of 54 household COVID-19 transmission studies that observed 77,758 participants, which was posted as a pre-print this summer and published in December.
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