4 ms·

How often do people attend public events of 1,000 or more people? From a public health perspective, I'm sure the safest number is 0. But along the curve of 0 to

How often do people attend public events of 1,000 or more people? From a public health perspective, I'm sure the safest number is 0. But along the curve of 0 to 1,000 -- is the risk increase linear? Exponential? It's hard to say how effective of a measure this is in reducing spread.

dpeck 7y ago
I read this as mostly targeting sporting events and big concerts. Where groups with high numbers of infrequent attendees and a high number of events (basketball, baseball, soccer) are in close contact in the stands for several hours at a time.
munk-a 7y ago
Not often - and that's why it's so risky. Events like concerts draw random folks from diverse workplaces and communities with a shared interest that otherwise wouldn't interact, as such it tends to be a good way for the disease to break out into new communities.
- Tepix 7y ago
  Quite a few people go to a sports match with tens of thousands of visitors every fortnight.
rgovostes 7y ago
The number of potential interactions is (n 2) or nC2, which is quadratic. Here's a plot: https://www.wolframalpha.com/input/?i=plot+Binomial%5Bn%2C+2%5D+for+n%3D1+to+1000 https://www.wolframalpha.com/input/?i=plot+Binomial%5Bn%2C+2... Obviously this is the simplest possible way to look at it, not modeling how many of those people actually come in contact with one another, the probability of transmission, etc.
es09 7y ago
If you assume a random person has a probability of carrying the virus at 0.001, here's the probability of someone in a crowd of N people being sick - https://www.wolframalpha.com/input/?i=plot+%281-%280.999%29%5En%29+for+n%3D1+to+2000 https://www.wolframalpha.com/input/?i=plot+%281-%280.999%29%... At around the 700 mark, the probability is > 0.5. So if you are in a crowd of 700+ people, someone's likely sick. Of course, you need to have some reasonable estimate of how many are carrying the virus in a given population to do this calculation.
ken 7y ago
As an individual, not that often. Collectively, a lot. Not counting the 2 outdoor amphitheatres, I can name 8 theatres in my area with capacity >1000. Several more in the 800-999 range, and I'm not sure if these thresholds would apply to "audience in the house" or "total souls in the building". Seattle's gathering limit is much lower (250) than SF's, and includes "social distancing" and other limitations, which essentially shuts down all concerts, plays, musicals, conventions, and lectures. For example, I see the 5th Avenue Theatre here (capacity: 2100) just cancelled their entire run of a show that opens this Friday (8 performances/week for 3 weeks). That would have potentially been >50,000 people. I estimate bans like this will prevent the intermingling of at least several hundred thousand people each month, in each metropolitan area which enacts it. I'm no expert on the spread of disease but that seems pretty significant.
blihp 7y ago
Conferences, concerts, sporting events, expos etc. They're just trying to slow down the rate at which it spreads. All of these types events also typically involve some amount of travel (whether on the part of the organizers, entertainers/presenters and attendees) It's not only the fact that it's a large number of people gathering, but also that it's a large number of people in close proximity to people they wouldn't otherwise be from out of town who are at higher risk of having been exposed to the virus. They pass it on to a few people at the event, who in turn take it home and give it to family members and in a few weeks the city has a big problem.
anigbrowl 7y ago
Me, maybe every 2-3 months. My wife, every 2-3 weeks.

dpeck 7y ago

I read this as mostly targeting sporting events and big concerts. Where groups with high numbers of infrequent attendees and a high number of events (basketball, baseball, soccer) are in close contact in the stands for several hours at a time.

munk-a 7y ago

Not often - and that's why it's so risky. Events like concerts draw random folks from diverse workplaces and communities with a shared interest that otherwise wouldn't interact, as such it tends to be a good way for the disease to break out into new communities.

Tepix 7y ago
Quite a few people go to a sports match with tens of thousands of visitors every fortnight.

rgovostes 7y ago

The number of potential interactions is (n 2) or nC2, which is quadratic. Here's a plot: https://www.wolframalpha.com/input/?i=plot+Binomial%5Bn%2C+2%5D+for+n%3D1+to+1000 https://www.wolframalpha.com/input/?i=plot+Binomial%5Bn%2C+2... Obviously this is the simplest possible way to look at it, not modeling how many of those people actually come in contact with one another, the probability of transmission, etc.

es09 7y ago

If you assume a random person has a probability of carrying the virus at 0.001, here's the probability of someone in a crowd of N people being sick - https://www.wolframalpha.com/input/?i=plot+%281-%280.999%29%5En%29+for+n%3D1+to+2000 https://www.wolframalpha.com/input/?i=plot+%281-%280.999%29%... At around the 700 mark, the probability is > 0.5. So if you are in a crowd of 700+ people, someone's likely sick. Of course, you need to have some reasonable estimate of how many are carrying the virus in a given population to do this calculation.

ken 7y ago

As an individual, not that often. Collectively, a lot. Not counting the 2 outdoor amphitheatres, I can name 8 theatres in my area with capacity >1000. Several more in the 800-999 range, and I'm not sure if these thresholds would apply to "audience in the house" or "total souls in the building". Seattle's gathering limit is much lower (250) than SF's, and includes "social distancing" and other limitations, which essentially shuts down all concerts, plays, musicals, conventions, and lectures. For example, I see the 5th Avenue Theatre here (capacity: 2100) just cancelled their entire run of a show that opens this Friday (8 performances/week for 3 weeks). That would have potentially been >50,000 people. I estimate bans like this will prevent the intermingling of at least several hundred thousand people each month, in each metropolitan area which enacts it. I'm no expert on the spread of disease but that seems pretty significant.

blihp 7y ago

Conferences, concerts, sporting events, expos etc. They're just trying to slow down the rate at which it spreads. All of these types events also typically involve some amount of travel (whether on the part of the organizers, entertainers/presenters and attendees) It's not only the fact that it's a large number of people gathering, but also that it's a large number of people in close proximity to people they wouldn't otherwise be from out of town who are at higher risk of having been exposed to the virus. They pass it on to a few people at the event, who in turn take it home and give it to family members and in a few weeks the city has a big problem.

anigbrowl 7y ago

Me, maybe every 2-3 months. My wife, every 2-3 weeks.