04-16-2020, 07:28 PM
I remember the much earlier results that suggested a serial interval of something like 2.5 days less than the incubation period, along with the results that the virus is heaviest early in the infection. I am not surprised at a finding that a significant portion of the infections are from pre-symptomatic patients.
Look at the Santa Clara County Dashboard for Testing. I see what appears to be multiple highs that are about 5 days apart:
March 27, March 31/April 1, April 6, April 11.
I believe we're seeing a wave of infections at roughly 5 days. For whatever reason, there was a bump some weeks back. A new wave of people are getting the disease, becoming infectious about the same time, and spreading it to a new generation of people. Some of those people are symptomatic and are going in for tests. What we are seeing is when those tests come back.
I would expect this bump to spread out and become less distinct over time because of variability in exposure to infectious time, exposure to symptom time, and symptom onset to test time. If it doesn't, that would suggest that another factor is in play.
If this were a 7-day cycle, I'd believe it is more likely some day of the week influence. I'm not aware of 5 day cycle that isn't related to the illness, but it could be, say, the cycle at which test materials are delivered or something hard for me to know.
Note that this cycle is the same as the incubation period. A possibility: when a person get the symptoms, someone goes to the drug store, some may go to a medical facility. The increases the chances of exposure for both sick & not-yet-sick patients. Voila, a 5 day cycle of new infections. The serial interval might be shorter (say, 3 days), but the activities that go one involved with symptom onset may perpetuate a 5-day cycle of infections.
This cycle might happen even if the infected person doesn't realize they have symptoms (or doesn't want to admit it). "Honey, I've got a {headache, sore throat, stuffy nose}. Can you go buy me some meds? And pick me up some chicken soup while you're out, please." At which point the spouse or parent (infected 2.5 days ago & newly infectious, but presymptomatic) goes out.
Santa Clara County's data can be shown as a table, but can't be downloaded San Francisco's data can be downloaded. I grabbed their test reports and summed all the results since the beginning for every 5th day (ie, one bucket is the sum of day 1, day 6, ...).
The last full set of buckets are 209, 232, 284, 243, 237. That may be a bump for day 3 + 5*n.
Look at the Santa Clara County Dashboard for Testing. I see what appears to be multiple highs that are about 5 days apart:
March 27, March 31/April 1, April 6, April 11.
I believe we're seeing a wave of infections at roughly 5 days. For whatever reason, there was a bump some weeks back. A new wave of people are getting the disease, becoming infectious about the same time, and spreading it to a new generation of people. Some of those people are symptomatic and are going in for tests. What we are seeing is when those tests come back.
I would expect this bump to spread out and become less distinct over time because of variability in exposure to infectious time, exposure to symptom time, and symptom onset to test time. If it doesn't, that would suggest that another factor is in play.
If this were a 7-day cycle, I'd believe it is more likely some day of the week influence. I'm not aware of 5 day cycle that isn't related to the illness, but it could be, say, the cycle at which test materials are delivered or something hard for me to know.
Note that this cycle is the same as the incubation period. A possibility: when a person get the symptoms, someone goes to the drug store, some may go to a medical facility. The increases the chances of exposure for both sick & not-yet-sick patients. Voila, a 5 day cycle of new infections. The serial interval might be shorter (say, 3 days), but the activities that go one involved with symptom onset may perpetuate a 5-day cycle of infections.
This cycle might happen even if the infected person doesn't realize they have symptoms (or doesn't want to admit it). "Honey, I've got a {headache, sore throat, stuffy nose}. Can you go buy me some meds? And pick me up some chicken soup while you're out, please." At which point the spouse or parent (infected 2.5 days ago & newly infectious, but presymptomatic) goes out.
Santa Clara County's data can be shown as a table, but can't be downloaded San Francisco's data can be downloaded. I grabbed their test reports and summed all the results since the beginning for every 5th day (ie, one bucket is the sum of day 1, day 6, ...).
The last full set of buckets are 209, 232, 284, 243, 237. That may be a bump for day 3 + 5*n.