Something is weird about that 3-10% secondary attack rate number. The study isn’t published yet, so I don’t know what exactly they’re measuring, but I’m pretty confident that people who share a household and hug each other will transmit at much greater than 10% probability.
This is a fairly late update, but closing the loop on this: I believe the 3-10% number ended up being the secondary attack rate among households where the infected person was isolated after diagnosis. So that’s an estimate of the rate of transmission during extended close contact before symptoms/diagnosis, not after, which makes more sense. I assume that extended close contact with a symptomatic infected person will result in very likely transmission.
Keep in mind that there may be substantial variation in the amount of viral shedding for infected people (there are superspreaders, presumably there are also subspreaders), as well as in the susceptibility of people to the virus (presumably there is some cross-immunity for people who have had a coronavirus-type common cold recently, for example.) So the transmission rate among household members can’t necessarily be estimated from the per-contact rate assuming each contact is an independent chance of transmission.
Something is weird about that 3-10% secondary attack rate number. The study isn’t published yet, so I don’t know what exactly they’re measuring, but I’m pretty confident that people who share a household and hug each other will transmit at much greater than 10% probability.
This is a fairly late update, but closing the loop on this: I believe the 3-10% number ended up being the secondary attack rate among households where the infected person was isolated after diagnosis. So that’s an estimate of the rate of transmission during extended close contact before symptoms/diagnosis, not after, which makes more sense. I assume that extended close contact with a symptomatic infected person will result in very likely transmission.
Keep in mind that there may be substantial variation in the amount of viral shedding for infected people (there are superspreaders, presumably there are also subspreaders), as well as in the susceptibility of people to the virus (presumably there is some cross-immunity for people who have had a coronavirus-type common cold recently, for example.) So the transmission rate among household members can’t necessarily be estimated from the per-contact rate assuming each contact is an independent chance of transmission.