Foppa2118
Registered User
- Oct 3, 2003
- 52,385
- 31,643
I don't think they care about that as much as they did at first, at least not here.
Tests aren't as reliable as they thought they were and they simply don't have enough. The #1 deciding factor appears to be how many people show up at the hospital...if they have enough room they'll open up the economy. If/when they get overwhelmed they'll close it again. Rinse and repeat until vaccine or herd immunity.
There are two types of tests that are important right now. The PCR tests to see if you currently have the virus, and the antibody tests to see if you ever had the virus.
Both tests will provide a critical piece of information that's important for evaluating risk. That's how many have/had the virus, including asymptomatic/presymptomatic, and therefore what percentage of the population may (and I stress may because we haven't done studies to know for sure) have built up enough immunity.
Herd immunity is calculated based upon the reproduction number (vaccine efficacy is factored in as well if there's a vaccine). The current estimated reproduction number for this novel coronavirus is around 2-2.5.
So they estimate the herd immunity threshold to be around 60%. Though some recent CDC studies estimated 85%.
We also don't know the risk of reinfection, or what level of immunity we will develop after contracting the virus, and how long we will have that immunity. There's a wide range that this could be, and it has big impacts on how quickly this will spread once we reopen the economy. Governors opening up their states early are betting people's lives that these will not be big factors.
Since both the PCR and antibody tests will give us an idea of what percentage of the population has had the virus, then if we assume (key word again assume) we develop some immunity after contracting the virus, then we'll have an idea of what the herd immunity is.
We don't have tests with high sensitivity or specificity right now, so we're getting some false negatives, and some positives that are picking up another virus. But the testing is still important for knowing more about the virus, and to aid in contact tracing.
Proper contact tracing is necessary for reopening the country too, otherwise we won't be able to contain the spread once we reopen. They estimate that we'll need 100,000-300,000 contact tracers which is a massive increase to the roughly 2,000 contract tracers they are using right now.
Without proper testing, we don't know what our herd immunity is. Without sufficient contact tracing, we won't be able to contain the spread.
So opening the economy back up without doing sufficient testing along the way, is doing so based on hopes and hunches that it won't return. It's not based on science. And that is risking a second wave even before the expected second wave in the fall.