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Not a great headline. What if I touch thousands of surfaces? Better (and based on the text): Few SARS-Cov-2 transmissions reported to have been via surface tra

Not a great headline. What if I touch thousands of surfaces? Better (and based on the text): Few SARS-Cov-2 transmissions reported to have been via surface transmission. And note: However, it is not clear what proportion of SARS-CoV-2 infections are acquired through surface transmission. Probably not many.

mninm 6y ago
Plus the report is referring to incidents of contact with contaminated surfaces not some random individual surface.
divbzero 6y ago
Even better would be using the article’s actual title: [1] “SARS-CoV-2 and Surface (Fomite) Transmission for Indoor Community Environments” [1]: https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html
em500 6y ago
> What if I touch thousands of surfaces? According to the article, that's probably risky if all of those thousands of surfaces are infected. But you make a good point: I have no idea how many infected surfaces I touched last week/month/year.
- jjk166 6y ago
  Being somewhat conservative, recently in the US there have been an average of around 75000 new cases of covid reported per day. Let's assume there's a 14 day window of infectivity (in reality this period is shorter but there are also unreported cases) so there's a little over 1 million people in the US who can infect surfaces at any given time. Pretending for a moment that these are evenly distributed, that's a 0.3% chance of any given person having covid. If a surface remains infected for 3 days, that would mean that 230 people would need to come into contact with it every 3 days for it to have a 50% chance of an infected person coming in contact with it. This would average out to 77 people per day. If 1000 people traffic a location over an 8 hour day, the odds that an infected person has contacted the surface in the past hour are around 31%. Now the odds of a an infected person actually contaminating a surface they touch are probably lower still, but this would seem to indicate most surfaces in public places have significant likelihood of being unsafe.
idoubtit 6y ago
If someone touched infected surface every day during the past year, their risk of being contaminated would be about 3.6% according to this study (10^-4 at each contact). Touching twice per day would not double the risk, since the process is not linear. So 3.6% is a a kind of absolute maximum. Note the paper suggest the real rate could be lower. For instance, a 10^-5 risk per contact would mean <0.4% risk for 365 contacts.
- jjk166 6y ago
  That's the odds if a person touched one surface every day. Touching the same surface twice would not double the risk, but touching two distinct surfaces would. Most people touch a lot more than one surface per day.
sampo 6y ago
> Few SARS-Cov-2 transmissions reported to have been via surface transmission. I haven't seen a single case of reported surface transmission. There was this case in a New Zealand quarantine hotel, where they first suspected a rubbish bin lid, which the persons had touched 20 hours apart. But now they think it was air moving, by opening the hotel room door from the room to the corridor, and then to the next room, when that door was opened right after. https://www.theguardian.com/global/2021/apr/04/how-new-zealands-covid-success-made-it-a-laboratory-for-the-world https://www.theguardian.com/global/2021/apr/04/how-new-zeala...

mninm 6y ago

Plus the report is referring to incidents of contact with contaminated surfaces not some random individual surface.

divbzero 6y ago

Even better would be using the article’s actual title: [1] “SARS-CoV-2 and Surface (Fomite) Transmission for Indoor Community Environments” [1]: https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html

em500 6y ago

> What if I touch thousands of surfaces? According to the article, that's probably risky if all of those thousands of surfaces are infected. But you make a good point: I have no idea how many infected surfaces I touched last week/month/year.

jjk166 6y ago
Being somewhat conservative, recently in the US there have been an average of around 75000 new cases of covid reported per day. Let's assume there's a 14 day window of infectivity (in reality this period is shorter but there are also unreported cases) so there's a little over 1 million people in the US who can infect surfaces at any given time. Pretending for a moment that these are evenly distributed, that's a 0.3% chance of any given person having covid. If a surface remains infected for 3 days, that would mean that 230 people would need to come into contact with it every 3 days for it to have a 50% chance of an infected person coming in contact with it. This would average out to 77 people per day. If 1000 people traffic a location over an 8 hour day, the odds that an infected person has contacted the surface in the past hour are around 31%. Now the odds of a an infected person actually contaminating a surface they touch are probably lower still, but this would seem to indicate most surfaces in public places have significant likelihood of being unsafe.

idoubtit 6y ago

If someone touched infected surface every day during the past year, their risk of being contaminated would be about 3.6% according to this study (10^-4 at each contact). Touching twice per day would not double the risk, since the process is not linear. So 3.6% is a a kind of absolute maximum. Note the paper suggest the real rate could be lower. For instance, a 10^-5 risk per contact would mean <0.4% risk for 365 contacts.

jjk166 6y ago
That's the odds if a person touched one surface every day. Touching the same surface twice would not double the risk, but touching two distinct surfaces would. Most people touch a lot more than one surface per day.

sampo 6y ago

> Few SARS-Cov-2 transmissions reported to have been via surface transmission. I haven't seen a single case of reported surface transmission. There was this case in a New Zealand quarantine hotel, where they first suspected a rubbish bin lid, which the persons had touched 20 hours apart. But now they think it was air moving, by opening the hotel room door from the room to the corridor, and then to the next room, when that door was opened right after. https://www.theguardian.com/global/2021/apr/04/how-new-zealands-covid-success-made-it-a-laboratory-for-the-world https://www.theguardian.com/global/2021/apr/04/how-new-zeala...