Your forecast seems plausible to me but on the lower end of what I’d have thought.
Attending a conference probably implies a lot more social mingling than the average Londoner is doing.
If a lot of vaccinated people are asymptomatic (at least initially) and LFTs aren’t very sensitive, would we expect a factor 7.5 reduction of conference attendees? I don’t have the figures to compare this with, but for instance, a factor of 5 doesn’t feel obviously wrong.
You say if no one were vaccinated, around 8 people would be infected on average? That seems low and like you went with the R0 of omicron in an unvaccinated population. But again, people are attending a conference. In a conference setting, even just one superspreader among the 8 people could infect >100 people if they were unvaccinated. I do think superspeaders are less likely in a triple-vaccinated population, but omicron ba.2 seems to be pretty undeterred by vaccination in some ways.
Incubation time is frequently <2 days with omicron, so you may have some people who get it at reception and infect more people on the last day of the conference. (I haven’t looked up whether the conference lasts 2.5 days or just 2 days, so that may also be relevant.) (On the other hand, some people may stop attending the conference once they feel unwell or if they take a second test and it’s now positive.)
FWIW, at the last EAG I saw people go to a crowded restaurant and then go back to the conference. If that’s done on the last day, it doesn’t matter. If it’s done on the first day, it may lead to more new infections.
Overall, I think >5% of attendees infected doesn’t seem implausible to me, but I would also put some probability on your number at the lower end. (With the nice weather, if people do most of their one-on-ones outside, I think that would reduce the risks by a lot!)
I also expect that the accounting will be complicated because of EAG afterparties or after events. Probably those will be riskier than the conference but the people who attend may already have had one of the omicrons and therefore be pretty safe, or they may not care about getting infected because they’re back to living life normally and EAG isn’t an inconvenient time for them to catch it.
Your forecast seems plausible to me but on the lower end of what I’d have thought.
Attending a conference probably implies a lot more social mingling than the average Londoner is doing.
If a lot of vaccinated people are asymptomatic (at least initially) and LFTs aren’t very sensitive, would we expect a factor 7.5 reduction of conference attendees? I don’t have the figures to compare this with, but for instance, a factor of 5 doesn’t feel obviously wrong.
You say if no one were vaccinated, around 8 people would be infected on average? That seems low and like you went with the R0 of omicron in an unvaccinated population. But again, people are attending a conference. In a conference setting, even just one superspreader among the 8 people could infect >100 people if they were unvaccinated. I do think superspeaders are less likely in a triple-vaccinated population, but omicron ba.2 seems to be pretty undeterred by vaccination in some ways.
Incubation time is frequently <2 days with omicron, so you may have some people who get it at reception and infect more people on the last day of the conference. (I haven’t looked up whether the conference lasts 2.5 days or just 2 days, so that may also be relevant.) (On the other hand, some people may stop attending the conference once they feel unwell or if they take a second test and it’s now positive.)
FWIW, at the last EAG I saw people go to a crowded restaurant and then go back to the conference. If that’s done on the last day, it doesn’t matter. If it’s done on the first day, it may lead to more new infections.
Overall, I think >5% of attendees infected doesn’t seem implausible to me, but I would also put some probability on your number at the lower end. (With the nice weather, if people do most of their one-on-ones outside, I think that would reduce the risks by a lot!)
I also expect that the accounting will be complicated because of EAG afterparties or after events. Probably those will be riskier than the conference but the people who attend may already have had one of the omicrons and therefore be pretty safe, or they may not care about getting infected because they’re back to living life normally and EAG isn’t an inconvenient time for them to catch it.