Asymptomatic infections

[OutsiderFan]

From other thread I just posted in, I saw a SCC Dr. say 40% of infections are asymptomatic.

This seems exceptionally high to me, and really begs the question of how so many people can carry the virus and not develop the disease.  Does anyone here have any answers or insights into what - if any - common denominators have been identified that prevents people from developing the disease?

My instinct tells me it has something to do with blood type because nothing else makes sense. I know someone who just lost smell/taste and was tired with no fever, but that was still considered symptoms.

[lex24]

From other thread I just posted in, I saw a SCC Dr. say 40% of infections are asymptomatic.

This seems exceptionally high to me, and really begs the question of how so many people can carry the virus and not develop the disease.  Does anyone here have any answers or insights into what - if any - common denominators have been identified that prevents people from developing the disease?

My instinct tells me it has something to do with blood type because nothing else makes sense. I know someone who just lost smell/taste and was tired with no fever, but that was still considered symptoms.

My instinct tells me the Dr. is wildly and irresponsibly guessing. Why do you assume the Dr is anywhere close to correct? Here is another take:

https://www.bmj.com/content/371/bmj.m4851

[BostonCard]

40% asymptomatic infections is in line with previous estimates.

BC

[M T]

From other thread I just posted in, I saw a SCC Dr. say 40% of infections are asymptomatic.

This seems exceptionally high to me, and really begs the question of how so many people can carry the virus and not develop the disease.  Does anyone here have any answers or insights into what - if any - common denominators have been identified that prevents people from developing the disease?

My instinct tells me it has something to do with blood type because nothing else makes sense. I know someone who just lost smell/taste and was tired with no fever, but that was still considered symptoms.

My instinct tells me the Dr. is wildly and irresponsibly guessing. Why do you assume the Dr is anywhere close to correct?  Here is another take:

https://www.bmj.com/content/371/bmj.m4851

For those that didn't follow the link, this article (published 12/21; I don't know when it was submitted) primarily summarizes information from other studies:

• The earlier high estimates of asymptomatic infections has been revised down to 17-20%.
  
• About 49% of those that initially report as asymptomatic eventually do get symptoms.
  
• There is no test to detect if a person is infectious.
  
• Viral load is similar whether or not a person has symptoms (but that doesn't necessarily mean they are equally infectious).
  
• The duration of viral shedding is shorter for those that remain asymptomatic.
  
• Viral culture studies suggest that people with SARS-CoV-2 can become infectious one to two days before the onset of symptoms and continue to be infectious up to seven days thereafter; viable virus is relatively short lived.
  
• Symptomatic and presymptomatic transmission have a greater role in the spread of SARS-CoV-2 than truly asymptomatic transmission.
  
• The transmission rates to contacts within a specific group (secondary attack rate) may be 3-25 times lower for people who are asymptomatic than for those with symptoms.[url=https://www.bmj.com/content/371/bmj.m4851#ref-1][/url]
  
• A city-wide prevalence study of almost 10 million people in Wuhan found no evidence of asymptomatic transmission
  
• People with a symptom of coughing would seem to be more likely to spread the virus to any contact.
  
• People without symptoms are more likely to have more contacts.
  

Between the 20% asymptomatic cases, and the 49% that are initially asymptomatic but later develop symptoms,  a number of 40% that are initially asymptomatic seems about right.

[JustAnotherFan]

From other thread I just posted in, I saw a SCC Dr. say 40% of infections are asymptomatic.

This seems exceptionally high to me, and really begs the question of how so many people can carry the virus and not develop the disease.  Does anyone here have any answers or insights into what - if any - common denominators have been identified that prevents people from developing the disease?

My instinct tells me it has something to do with blood type because nothing else makes sense. I know someone who just lost smell/taste and was tired with no fever, but that was still considered symptoms.

My instinct tells me the Dr. is wildly and irresponsibly guessing. Why do you assume the Dr is anywhere close to correct?  Here is another take:

https://www.bmj.com/content/371/bmj.m4851

For those that didn't follow the link, this article (published 12/21; I don't know when it was submitted) primarily summarizes information from other studies:

• The earlier high estimates of asymptomatic infections has been revised down to 17-20%.
  
• About 49% of those that initially report as asymptomatic eventually do get symptoms.
  
• There is no test to detect if a person is infectious.
  
• Viral load is similar whether or not a person has symptoms (but that doesn't necessarily mean they are equally infectious).
  
• The duration of viral shedding is shorter for those that remain asymptomatic.
  
• Viral culture studies suggest that people with SARS-CoV-2 can become infectious one to two days before the onset of symptoms and continue to be infectious up to seven days thereafter; viable virus is relatively short lived.
  
• Symptomatic and presymptomatic transmission have a greater role in the spread of SARS-CoV-2 than truly asymptomatic transmission.
  
• The transmission rates to contacts within a specific group (secondary attack rate) may be 3-25 times lower for people who are asymptomatic than for those with symptoms.[url=https://www.bmj.com/content/371/bmj.m4851#ref-1][/url]
  
• A city-wide prevalence study of almost 10 million people in Wuhan found no evidence of asymptomatic transmission
  
• People with a symptom of coughing would seem to be more likely to spread the virus to any contact.
  
• People without symptoms are more likely to have more contacts.
  

Between the 20% asymptomatic cases, and the 49% that are initially asymptomatic but later develop symptoms,  a number of 40% that are initially asymptomatic seems about right.

Thank you, MT.

Posts like this are why we should not close this forum until May.

[DocSavage87]

For those that didn't follow the link, this article (published 12/21; I don't know when it was submitted) primarily summarizes information from other studies:

• The earlier high estimates of asymptomatic infections has been revised down to 17-20%.
  
• About 49% of those that initially report as asymptomatic eventually do get symptoms.
  
• There is no test to detect if a person is infectious.
  
• Viral load is similar whether or not a person has symptoms (but that doesn't necessarily mean they are equally infectious).
  
• The duration of viral shedding is shorter for those that remain asymptomatic.
  
• Viral culture studies suggest that people with SARS-CoV-2 can become infectious one to two days before the onset of symptoms and continue to be infectious up to seven days thereafter; viable virus is relatively short lived.
  
• Symptomatic and presymptomatic transmission have a greater role in the spread of SARS-CoV-2 than truly asymptomatic transmission.
  
• The transmission rates to contacts within a specific group (secondary attack rate) may be 3-25 times lower for people who are asymptomatic than for those with symptoms.[url=https://www.bmj.com/content/371/bmj.m4851#ref-1][/url]
  
• A city-wide prevalence study of almost 10 million people in Wuhan found no evidence of asymptomatic transmission
  
• People with a symptom of coughing would seem to be more likely to spread the virus to any contact.
  
• People without symptoms are more likely to have more contacts.
  

Between the 20% asymptomatic cases, and the 49% that are initially asymptomatic but later develop symptoms,  a number of 40% that are initially asymptomatic seems about right.

Agree.  I also think there isn't consistent use of terms in reporting between "asymptomatic" and "pre-symptomatic".  Here's an example of a pre-symptomatic case that spread the virus during a gathering despite testing.  Remember that just because you test positive doesn't mean you are free from the virus.  It takes time for test positivity and there's a non-negligible % of false negative results as well.  (We saw a false positive crush any chance we had of winning vs Oregon.)