It’s been months. We don’t have concrete examples of infection via surfaces. At all. It increasingly seems like while such a route is possible, and must occasionally happen, getting enough virus to cause an infection, in a live state, via this route, is very hard.
On April 23 I wrote on Facebook:
For most things, I’m just leaving it to air out for 3+ days. If I need to put it in the fridge or freezer, I disinfect it first.
My gestalt amateur sense is that surface transmission from people you aren’t spending a bunch of in-person time with seems really low. (Do we even know of any clear examples of this, for COVID-19?) But I’m in a dusty/moldy house in a remote area with no nearby ICUs, so I’d rather err on the side of caution.
(The dust thing seems less important to me now that I’m thinking of COVID-19 as disproportionately endangering people who have cardiovascular issues, not so much people who have respiratory issues.)
Eloise Rosen replied:
> Do we even know of any clear examples of this, for COVID-19?
Yes!
“A woman aged 55 years (patient A1) and a man aged 56 years (patient A2) were tourists from Wuhan, China, who arrived in Singapore on January 19. They visited a local church the same day and had symptom onset on January 22 (patient A1) and January 24 (patient A2). Three other persons, a man aged 53 years (patient A3), a woman aged 39 years (patient A4), and a woman aged 52 years (patient A5) attended the same church that day and subsequently developed symptoms on January 23, January 30, and February 3, respectively. *Patient A5 occupied the same seat in the church that patients A1 and A2 had occupied earlier that day (captured by closed-circuit camera)* (5). Investigations of other attendees did not reveal any other symptomatic persons who attended the church that day.”
I haven’t seen other examples, though, so I remain skeptical that surface transmission is a big deal. Erin Bromage previously claimed that the South Korean call center outbreak occurred “roughly 6% from fomite transfer” but then retracted the claim; not sure what happened there.
OK, so if true we have one hard example, so presumably it is *possible*. But I also haven’t heard of a second one, and also asymptomatic transmission is a thing, etc etc.
It would be weird if we didn’t have one case somewhere that has a plausible surface vector even if they were completely safe.
A detailed investigation of outbreak in a South African hospital found pretty good evidence for transmission by surfaces or indirect contact (nurse touches infected person A and then later touches susceptible person B). Doesn’t mean risk from deliveries is significant but worth being wary of surfaces in general.
According to current evidence, SARS‐CoV‐2 is transmitted between people through respiratory droplets and contact routes. Droplet transmission may also occur through fomites so transmission of the virus can occur by direct contact with an infected person or indirect contact with surfaces in the immediate environment of that person or with objects used on the infected person (e.g. stethoscope or thermometer). The spatial distribution of cases and exposed individuals who became infected on the wards suggests that indirect contact via health care workers or fomite transmission were the predominant modes of transmission between patients in this outbreak. Direct droplet or contact transmission would be plausible where the people that were exposed were located in close proximity to an infectious case, e.g. P4 in the bed directly opposite P3 on MW1 between 13 ‐ 16 March (Figure 7); or X1 and X3 sharing a four‐bedded bay with P7 on MW1 between 27 March ‐ 2 April (Figure 10). However, in other examples the exposed individuals were located in different rooms and different areas of the ward, making indirect contact via health care workers or fomite transmission more plausible. We also present evidence suggestive of direct droplet transmission from a symptomatic health care worker to two patients on the neurology ward.
Right, I was thinking the same thing—not just a person, but medical personnel. So you’re going from patient 1, to someone’s hands, who is then directly touching patient 2, plausibly even patient 2′s mucous membranes. That’s much more direct than a typical fomite contact, which is more like face-hands-fomite-hands-face (or if you sneeze on a doorknob, face-fomite-hands-face.)
On April 23 I wrote on Facebook:
(The dust thing seems less important to me now that I’m thinking of COVID-19 as disproportionately endangering people who have cardiovascular issues, not so much people who have respiratory issues.)
Eloise Rosen replied:
I haven’t seen other examples, though, so I remain skeptical that surface transmission is a big deal. Erin Bromage previously claimed that the South Korean call center outbreak occurred “roughly 6% from fomite transfer” but then retracted the claim; not sure what happened there.
OK, so if true we have one hard example, so presumably it is *possible*. But I also haven’t heard of a second one, and also asymptomatic transmission is a thing, etc etc.
It would be weird if we didn’t have one case somewhere that has a plausible surface vector even if they were completely safe.
A detailed investigation of outbreak in a South African hospital found pretty good evidence for transmission by surfaces or indirect contact (nurse touches infected person A and then later touches susceptible person B). Doesn’t mean risk from deliveries is significant but worth being wary of surfaces in general.
https://www.sciencemag.org/news/2020/05/study-tells-remarkable-story-about-covid-19-s-deadly-rampage-through-south-african
The surface being a person seems important in that example. Reduces the number of steps, if nothing else.
Right, I was thinking the same thing—not just a person, but medical personnel. So you’re going from patient 1, to someone’s hands, who is then directly touching patient 2, plausibly even patient 2′s mucous membranes. That’s much more direct than a typical fomite contact, which is more like face-hands-fomite-hands-face (or if you sneeze on a doorknob, face-fomite-hands-face.)