Well, we’re NOT doctors, and he might be having some fun at our expense because we wouldn’t be able to tell (actually I already knew seroprevalance to be a real word…)
I’m not in a hot spot, otherwise I’d love to volunteer for it. The friend (housemate) who brought back a bad cold from Philly and shared with me, in early January, is convinced that COVID is a real possibility because she truly felt wretched for several weeks, including a brief improvement before worsening. Me, not so much: my cold, while unpleasant, did not follow typical COVID symptoms. No fever, the cough was productive which I gather is not typical (maybe in an asthmatic it behaves differently?), and I didn’t feel all that ill for all that long - just my sleep was disrupted from the coughing.
Not clear from the article: does the CDC plan to do followups on those whose blood lights up, to see if they are still showing antibodies a few months later?
How difficult would it be to do the antibody tests along with, um … say a blood drive? Donate blood, get a free rapid Covid test, and do the antibody test on those testing negative?
So among a fairly small self-selected sample of apparently healthy asymptomatic blood donors in a region of Italy that is near peak COVID-19 two thirds had had asymptomatic infections. Small and self-selected appropriately emphasized, some may have had the same thought process Mama Zappa shares, but still …
This also from that article which is consistent with the hypothesis that kids get so little identifiable or significant COVID-19 (and may be minimally contagious with it) because of their relative frequency and recency of multiple infections with the variety of other human coronaviruses that cause common colds.
Anyones ideas on the thought that California’ s (current) low infection fate is due to the virus passing through as early as Nov. 2019, and giving some degree of herd immunity?
Blood antibody testing started on 3200 people.
I would be completely unsurprised to read of a large number of Californians with evidence of past infection, perhaps asymptomatic or even labeled clinically as influenza or pneumonia not otherwise specified. I have no idea how antibody levels now can prove if that happened in March or in December.
A slight hijack, hopefully not too off-topic – do they do these seroprevalence surveys for the flu? Once this is flattening out, will we be able to get good, apples-to-apples comparisons between how contagious SARS-COV-2 is compared to various flus.
My layman’s impression is that it’s much more contagious, but I’ve never seen this kind of coverage for flu outbreaks, so it may be confirmation bias.
They do them for sure but I don’t know how regularly. There was a bunch of follow up seroprevalence surveys for H1N1, for instance. I would hope they’re doing that extensively this year so we can muddle out what was flu and what was covid-19
I had something in Nov, Dec where I was so shortwinded I couldn’t even shop. 100 steps I was ready to keel over. Dry cough, nose clear but not aware of a fever or Muscle aches.
The IEEE has a nice layperson (well, layengineer) write-up on the testing methods and tests being rolled out for COVID-19, with links to detailed information on the who, what, where.
I am hoping the 5/13 minute tests for the virus are going to drastically increase the rate of testing for infection (the manufacturer claims 50,000 tests a day production rate).
”Herd immunity” requires a significant portion of the population (30% to 50% at least, depending upon the degree of infectiousness) to be immunized, either by vaccine or prior exposure. If 30% or more of the nearly 40 million population of California were infected, even assuming an asymptomatic rate of 80% would still be 8,000,000 people. If there is even only a 5% incidence of severe illness and net case fatality rate of 0.3% (which is about the low end of credible estimates) that would still be a net number of 400,000 new patients and 24,000 additional or premature deaths. If we saw an increase of severe acute respiratory distress across a period of three months that would have flagged epidemic surveillance systems as emergency rooms and ICUs registered an enormous unattributed spike in morbidity and mortality. And it isn’t as if California is walled off from the rest of the country. Los Angeles is a major tourist destination with Disneyland and Universal Studios being dense concentrations of crowds as well as a major transit center to international flights. The San Francisco Bay Area is obviously a major tech business hub with regular travel from and to China and other nations in Asia as well as domestic travel. Even without serology (which would not be able to tell you the timing of infections) it just doesn’t pass the smell test that the SARS-CoV-2 virus could have been circulating in North America undetected for several months before a sudden spike in severe illness and death.
In reality, given the apparent infectiousness of SARS-CoV-2, you’d probably need an immunity level exceeding 50% to get a really significant attenuation of spread, especially as it appears that the virus may be spreading by aerosol routes instead of just intimate contact or fomites (droplets on surface transferred hand-to-mouth). It should be noted that San Francisco instituted “shelter-in-place” protocols a week before California implemented its “Stay At Home” order which was the most vigorous isolation direction in the US to that date. California has also been significantly deficient in getting wide scale testing available even for highly symptomatic patients for reasons largely left for another forum. So, despite a certain…political imperative to attribute the lower rates of infection and death to “herd immunity”, it seems more likely to be a combination of a lack of good testing samples and the effectiveness of isolation measures. Which, of course, argues for maintaining a lockdown until the risks of overwhelming health systems is mitigated to reduce unnecessary death.
EXCEPT that the unusual third hump occurred while lab confirmation of influenza went DOWN. (Same cite.) This can be seen specific to California even more so. https://www.cdph.ca.gov/Programs/CID/DCDC/CDPH%20Document%20Library/Immunization/Week2019-2012_FINALReport.pdf. Lab proven influenza admissions dropped while pneumonia admissions jumped really beginning in February. Interestingly California had a worse pneumonia year than usual and more so than the rest of the country seemed to have. It really does fit with COVID19 being there for while lost in the influenza statistics noise.
No estimates of infection fatality rate can “credible” without data on the rates of undocumented and unsuspected infections in the general population, inclusive of those asymptomatic and minimally symptomatic to the degree of barely noticing it. That is the data this thread is anxiously waiting for.
But that third hump starts in early March, which I would agree corresponds with the likely contagion of SARS-CoV-2 preceding the COVID-19 outbreak. The first peak appears in November and the second one peaking in late January/early February, which is consistent with previous trends (probably some relationship with students going back to school and passing viruses around). California has had an unusually cold and wet winter which it is still “enjoying” (I’m actually personally enjoying it but we usually have sunny warm weather by mid-February) so a higher incidence of pneumonia might be somewhat explained just by the environmental conditions even with a pathogen-specific outbreak. But I’ll go back to the reality that if SARS-CoV-2 were really making the rounds back in early November, we’d be seeing a very significant quantity of unexplained ARDS patients (not just typical pneumonia presentations but aggressive respiratory failures in patients without previous explicable morbidity) and it just isn’t there.
New York is often cited as a special case for transmission for how dense the population is and how much the population uses public transit, but while the Bay Area is not comparable in strict density or the quantity of people on public transit, it is still dense enough with open plan workspaces and people in public spaces where people are on top of one another that you’d expect to see more flareups prior to when the epidemic was formally recognized, which is why San Francisco issued the “Shelter In Place” order so early. We don’t see any of that, and in fact the Bay Area has been remarkably quiet in terms of hospitalizations. For the virus spreading/herd immunity argument to make sense, the virus would have to have suddenly turned virulent, or a second much less virulent strain would have had to circulate first to provide immunity which was an early thesis but while several minor strains have emerged there isn’t any evidence that any are significantly less virulent than others.
Agreed, and that is why I picked 0.3% as a low end for the CFR. It could in fact be lower if the rate of asymptomatic cases is higher. However, from the best samples we have (primarily South Korea, but also some testing done in Germany, Iceland, and comprehensive testing of a town in Italy) the rate seems to be somewhere slightly above 1%. My totally off-the-cuff guestimate is that it’ll come in lower once we have a statistically significant sample of antibody testing, and maybe low enough to justify the more optimistic estimates of total deaths that we’re seeing but I wouldn’t make any plans on reducing isolation measures until there is solid data in hand.
Thank you all for this discussion. Stranger On a Train I would note that Feb in California is one the wettest months of the year. Even for SoCal. Systems usually swing north by March/April, but the"normal" storm track has been screwed up now going back 15 years or so?
This year Feb was one of the driest on record.
As I type this its is 55f out and been raining all day (and week) in Santa Barbara. Interesting April…(before Gray may and June gloom)
edit to add:
Questions: Is seasonal flu temperature related? My laymans understanding was that since more people were in close contact due to being indoors, that the infection rates spike because of that. So basically the flue/colds/virus’s are here year round?
Mutation rate? Is it continual? A simple answer or reference link would be great!! Thank you.
15% of the population already infected and a 0.4% mortality rate seem quite favorable for the hypothesis that coronavirus is only moderately more deadly and a lot more contagious than the flu, and that the primary risk is not the mortality rate itself but the potential to overwhelm the healthcare system with an entire season’s worth of illness in the space of a a few weeks.
I just went to the worldometer site and looked up the testing and infection numbers for the last two days (8th April to 10th April)
In that time, about 400,000 coronavirus tests were done in Germany, and 10,000 new cases of coronavirus were diagnosed.
So, right now, around 2.5% of people who get tested for coronavirus in Germany, turn out to have a positive test.
This doesn’t seem to be compatible with the claim that 15% of the general population are infected. I don’t think the district that this study took place in can be representative of the whole country
(actually I already knew seroprevalance to be a real word…)