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发帖数: 43926 | 1 https://www.nejm.org/doi/full/10.1056/NEJMoa2001316
METHODS
We collected information on demographic characteristics, exposure history,
and illness timelines of laboratory-confirmed cases of NCIP that had been
reported by January 22, 2020. We described characteristics of the cases and
estimated the key epidemiologic time-delay distributions. In the early
period of exponential growth, we estimated the epidemic doubling time and
the basic reproductive number.
RESULTS
Among the first 425 patients with confirmed NCIP, the median age was 59
years and 56% were male. The majority of cases (55%) with onset before
January 1, 2020, were linked to the Huanan Seafood Wholesale Market, as
compared with 8.6% of the subsequent cases. The mean incubation period was 5
.2 days (95% confidence interval [CI], 4.1 to 7.0), with the 95th percentile
of the distribution at 12.5 days. In its early stages, the epidemic doubled
in size every 7.4 days. With a mean serial interval of 7.5 days (95% CI, 5.
3 to 19), the basic reproductive number was estimated to be 2.2 (95% CI, 1.4
to 3.9).
CONCLUSIONS
On the basis of this information, there is evidence that human-to-human
transmission has occurred among close contacts since the middle of December
2019. Considerable efforts to reduce transmission will be required to
control outbreaks if similar dynamics apply elsewhere. Measures to prevent
or reduce transmission should be implemented in populations at risk. (Funded
by the Ministry of Science and Technology of China and others.) | H********g
发帖数: 43926 | | H********g
发帖数: 43926 | 3
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