I assume people had to quarantine for two weeks after the concert?
Kucirka et al (https://www.acpjournals.org/doi/10.7326/M20-1495) did a pooled analysis of seven other studies and found that "over the 4 days of infection before the typical time of symptom onset (day 5), the probability of a false-negative result in an infected person decreases from 100% (95% CI, 100% to 100%) on day 1 to 67% (CI, 27% to 94%) on day 4. On the day of symptom onset, the median false-negative rate was 38% (CI, 18% to 65%). This decreased to 20% (CI, 12% to 30%) on day 8 (3 days after symptom onset) then began to increase again, from 21% (CI, 13% to 31%) on day 9 to 66% (CI, 54% to 77%) on day 21."
A lot of folks are jumping into this thread very confident that my numbers are wrong, but they're pretty well established and uncontroversial.
Let's assume the "real" share of infectious people in the population is 10/100k (That's twice as much as the most recent reported 7-day incidence (5.1/100k) of new infections for Leipzig, the area where the study was performed.)
Further let's assume a PCR Test has a 30% FNR, and a 10% FPR (numbers completely made up, I don't have a source).
Then out of 1500 People who have tested negative, we'd expect 0.05 to have the virus.
Once the expected value starts to creep over 1, then that's enough to infect quite a lot of people. It's not too much past that to expect that one of the infected has 'underlying condition' and risking death.
In British Coloumbia there's been a big outbreak due to a single gathering in the interior, notably (shamefully) attended by Medics and Doctors.
It's a little risky.
It's just not the time to have major gatherings, but at least this one is in the service of the science of 'stopping it' - which is better than most places are doing.
Kucirka et al (https://www.acpjournals.org/doi/10.7326/M20-1495) did a pooled analysis of seven other studies and found that "over the 4 days of infection before the typical time of symptom onset (day 5), the probability of a false-negative result in an infected person decreases from 100% (95% CI, 100% to 100%) on day 1 to 67% (CI, 27% to 94%) on day 4. On the day of symptom onset, the median false-negative rate was 38% (CI, 18% to 65%). This decreased to 20% (CI, 12% to 30%) on day 8 (3 days after symptom onset) then began to increase again, from 21% (CI, 13% to 31%) on day 9 to 66% (CI, 54% to 77%) on day 21."
> the person was unlikely to be infectious at the time of the test.
https://www.health.govt.nz/our-work/diseases-and-conditions/...
Of course if you are testing proper samples from the airways and they come back negative, it’s not very likely these people can infect others through droplets from their airways at that moment. The problem is that they might be in the incubation period but that is irrelevant here.
And anyway PCR does not nearly have a 30% false negative rate, I’m not quite sure where you got these stats.
Kucirka et al (https://www.acpjournals.org/doi/10.7326/M20-1495) did a pooled analysis of seven other studies and found that "over the 4 days of infection before the typical time of symptom onset (day 5), the probability of a false-negative result in an infected person decreases from 100% (95% CI, 100% to 100%) on day 1 to 67% (CI, 27% to 94%) on day 4. On the day of symptom onset, the median false-negative rate was 38% (CI, 18% to 65%). This decreased to 20% (CI, 12% to 30%) on day 8 (3 days after symptom onset) then began to increase again, from 21% (CI, 13% to 31%) on day 9 to 66% (CI, 54% to 77%) on day 21."
You are mistaken.
Your second study is flawed as indicated by the comments on it, it’s a meta study based on poor data.
If you choose a point and go looking for studies to support it, regardless of quality and ignoring studies that do not, that’s not science.
And by the way, your studies are about something that is not important here. What is important here is if the patient carries virus particles in his airways so they can infect others, not if they are infected themselves.
Why would they not wear masks?
The amount of infected people is so low it’s basically impossible to scientifically test infections, that’s not what they are doing (especially given they tested everyone in advance). They are testing crowd movement, how many people do you get close to etcetera.