
Coronavirus is most contagious before symptoms occur - bookofjoe
https://www.nature.com/articles/s41591-020-0869-5
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bookofjoe
Retired physician here, age 71. I consider everyone a carrier and proceed
accordingly. I will continue to do so indefinitely, regardless of changes in
governmental directives.

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marojejian
Hmm, this seems like a pretty big deal, and should give us caution to not have
confidence we are not spreading covid-19 just because we feel fine. Makes
masks seem more key.

"We estimated that 44% (95% confidence interval, 25–69%) of secondary cases
were infected during the index cases’ presymptomatic stage" "Disease control
measures should be adjusted to account for probable substantial presymptomatic
transmission."

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acqq
"For a reproductive number of 2.5 (ref. 2), _contact tracing and isolation
alone are less likely to be successful if more than 30% of transmission
occurred before symptom onset, unless >90% of the contacts can be traced_.
This is more likely achievable if the definition of contacts covers 2 to 3
days prior to symptom onset of the index case, as has been done in Hong Kong
and mainland China since late February. Even when the control strategy is
shifting away from containment to mitigation, contact tracing would still be
an important measure, such as when there are super-spreading events that may
occur in high-risk settings including nursing homes or hospitals. _With a
substantial proportion of presymptomatic transmission, measures such as
enhanced personal hygiene and social distancing for all would likely be the
key instruments for community disease control._ "

As I see it, it confirms the importance of enhanced hygiene and social
distancing.

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sjg007
We will be quarantining whole supermarkets

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travisporter
The article abstract states "We observed the highest viral load in throat
swabs at the time of symptom onset, and inferred that infectiousness peaked on
or before symptom onset." This finding is extremely significant, but I think
it may be "very contagious" not "most contagious" before symptoms occur

