A
Hong Kong research letter published at the CDC documents two cases of Omicron, where the easiest explanation is that one case got it from the other, without any real contact, even at a distance. Â Two tourists, arriving a day apart, were set up in quarantine in rooms in a quarantine hotel opposite one another. Â Video indicates that neither left their room during quarantine. Â PCR testing is done every 3 days, so they would not have been tested on the same day. Â Other than testing, the only time they opened their doors was to get food dropped off at their door. Â No one entered their rooms. Â No items were shared.
Both tourists had two doses of Pfizer (late May/early June for 2nd dose). Â Both had negative PCR tests within 3 days of arrival.
Nov 10. Â Tourist A arrives from South Africa and is quarantined in a quarantine hotel.
Nov 11. Â Tourist B arrives from Canada and is quarantined in the same quarantine hotel across the hall from Tourist A.
Nov 13. Â Tourist A tests positive for COVID without symptoms. Â He has a high viral load.
Nov 14. Â Tourist A is hospitalized
Nov 17. Â Tourist B develops mild symptoms.
Nov 18. Â Tourist B tests positive for COVID with a high viral load and is hospitalized.
Both were infected with the Omicron variant. Â The two virus sequence differ by 1 nucleotide. Â Neither Tourist A nor Tourist B's virus sequence are exactly like any others previously reported. Â Tourist A's differs by 1 nt from 2 other early sequences out of Botswana (from Nov. 11).
(I believe this was the first case of Omicron reported to WHO.)
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They don't go into detail about food delivery nor about ventilation of the hallway. Â If Tourist A is highly infectious on Nov 13 (or 12), he may have introduced the virus into the hallway on that day when he opened his door for food (whether or not he was wearing a mask). Â If Tourist B subsequently (and soon) opened his door, he may have inhaled some of the virus (if he wasn't wearing a mask). Â He then shows up with symptoms 4 days later.
Alternatively, Tourist A's door was opened to take him to the hospital on the 14th, and possibly to clean his room. Tourist B was given a PCR test that day. When he took his mask off so he could be swabbed, he inhaled a nose full of virus still in the air of the corridor.
I think the 15 minutes within 6 feet arbitrary definition of "close contact" may soon go the way of the "You don't need a mask" advice.