Three studies are referenced in this article.
The first is Household Transmission of SARS-CoV-2: A Systematic Review and Meta-analysis. Published by the Journal of the American Medical Association. December 14, 2020
Household secondary attack rates were increased from symptomatic index cases (18.0%; 95% CI, 14.2%-22.1%) than from asymptomatic index cases (0.7%; 95% CI, 0%-4.9%)
The CDC defines the secondary attack rate as the spread of disease among contacts. It is calculated as the number of new cases among contacts of an infected person divided by the total number of contacts by that same infected person multiplied by 100.
If a COVID-positive individual has 100 contacts and only 0.7 got infected, the secondary attack rate is 0.7%.
The second study is from the journal Pediatrics, Incidence and Secondary Transmission of SARS-CoV-2 Infections in Schools.
The study included more than 90,000 students and staff. A quote from the report said,
No instances of child-to-adult transmission of SARS-CoV-2 were reported within schools.
Finally, a study involving 92% of the population of Wuhan, China, after their lockdown. That’s a 9,899,828 sample size. Bigger sample-sized studies make more meaningful conclusions.
This was published in Nature and aptly titled Post-lockdown SARS-CoV-2 nucleic acid screening in nearly ten million residents of Wuhan, China. Here’s a quote from the abstract.
There were no positive tests amongst 1,174 close contacts of asymptomatic cases.
That means among asymptomatic COVID-19 positive cases, 1,174 of their close contacts were tested for COVID-19, and none of those contacts got infected from the asymptomatic cases.
Conclusion:
The three studies show that asymptomatic transmission is minimal to none. Considering that the cycle threshold for the PCR testing at the time the studies were made was very high (33 to 45), which can lead to as much as 90 to 97% false positives. Maybe some of the asymptomatic ones are false positives. They have no viable SARS-CoV-2 to transmit.
That is why to prevent the false increase of breakthrough infections after COVID vaccination, the CDC instructed the state health departments in their COVID-19 Vaccine Breakthrough Case Investigation and Reporting to submit specimens with a cycle threshold (Ct) value of ≤ 28 for sequencing.
Aside from preventing false positives that will make the vaccines look ineffective, low CT thresholds are needed to sequence the virus to know if it is a mutant variant.
Why is that? Because Ct cycles of more than 28 are likely to be false-positive and will not grow any viruses for sequencing.
On the other hand, PCR testing with Ct cycles of more than 28, which was the standard before the vaccination, will only detect parts of the virus and hence more likely to be non-infectious.
With this knowledge, it becomes easier to resume a normal life and not be scared.
Knowledge about Covid-19 is rapidly evolving. Information may update as new studies are made. Stay current by subscribing. Feel free to share and like.
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- Antibodies to COVID-19 can Exist in the Uninfected
- CD4+ Cross-Reactivity between Seasonal Coronavirus Colds and COVID-19
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