key: cord-292972-p7ifetgw authors: Jiang, Xuan; Rayner, Simon; Luo, Min‐Hua title: Does SARS‐CoV‐2 has a longer incubation period than SARS and MERS? date: 2020-02-24 journal: J Med Virol DOI: 10.1002/jmv.25708 sha: doc_id: 292972 cord_uid: p7ifetgw The outbreak of a novel coronavirus (SARS‐CoV‐2) since December 2019 in Wuhan, the major transportation hub in central China, became an emergency of major international concern. While several etiological studies have begun to reveal the specific biological features of this virus, the epidemic characteristics need to be elucidated. Notably, a long incubation time was reported to be associated with SARS‐CoV‐2 infection, leading to adjustments in screening and control policies. To avoid the risk of virus spread, all potentially exposed subjects are required to be isolated for 14 days, which is the longest predicted incubation time. However, based on our analysis of a larger dataset available so far, we find there is no observable difference between the incubation time for SARS‐CoV‐2, severe acute respiratory syndrome coronavirus (SARS‐CoV), and middle east respiratory syndrome coronavirus (MERS‐CoV), highlighting the need for larger and well‐annotated datasets. avoid the risk of virus spread, all potentially exposed subjects are required to be isolated for 14 days, which is the longest predicted incubation time. However, based on our analysis of a larger dataset available so far, we find there is no observable difference between the incubation time for SARS-CoV-2, severe acute respiratory syndrome coronavirus (SARS-CoV), and middle east respiratory syndrome coronavirus (MERS-CoV), highlighting the need for larger and well-annotated datasets. Although phylogenetic analysis indicate it belongs to the same β-coronavirus genus as severe acute respiratory syndrome coronavirus (SARS-CoV) and middle east respiratory syndrome coronavirus (MERS-CoV), SARS-CoV-2 has a higher genome-sequence similarity to several β-coronaviruses detected in bats. It shows more than 96% identity to a known bat coronavirus, compared to 79.5% identity to SARS-CoV BJ01. 1, 2 Studies investigating the clinical characteristics, epidemic and treatment have also been carried out. According to clinical investigation of the pneumonia cases in China, SARS-CoV-2 infection causes SARS with major symptoms such as fever, cough, myalgia, or fatigue and minor symptoms such as sputum production, headache, hemoptysis, and diarrhea. 3 As more data become available, additional case features are also being revealed. More than half of the initial cases had visited the Wuhan Huanan seafood market. It is also apparent that the outcome of SARS-CoV-2 pneumonia is enormously destructive, despite a mortality rate less than 3% (according to the latest data on February 8th, 2020 in China 4 ) when compared with SARS-CoV (mortality rate 9.6%) and MERS-CoV (mortality rate 9.6% and 34%). 5 However, the spread of SARS-CoV-2 infection is much broader than SARS or MERS-CoV and involves larger numbers of patients. The symptom onset date of the first identified patient infected by SARS-CoV-2 was December 1st, 2019, which is about 14 days before the subsequent reported cases. 3 The first estimate of mean incubation time was based on the exposure information of 10 confirmed early SARS-CoV-2 infected cases in Wuhan, China and was predicted to be 5. The reported estimate of the SARS-CoV-2 incubation time was based on limited case data. A subsequent unpublished study from 88 cases estimated a mean incubation time of 6.4 days (95% CI, 5.6-7.7 days). 9 However, the data were taken from an online resource, 10 and only a subset of these data (25 patients) had both clearly defined start and stop dates for exposure, together with a date for onset of symptoms. The patients from Wuhan had extended exposure times by December 14th. As an alternative approach, we limited our dataset to the patients whose exposure periods were well-defined. As of February 8th, 2020, this comprised 50 patients (Supporting Information Material). We also collected additional raw data from earlier reports on SARS (153 patients) and MERS (70 patients) outbreaks (Supporting Information Material). We then fitted "Weibull", "lognormal," and "gamma" functions to the respective datasets. These are shown for SARS-CoV-2, SARS, and MERS datasets in Figure 1A -C, respectively. The corresponding mean and 95% Table S1 for raw data and references datasets. These are summarized as boxplots in Figure 1D and have notably varying distributions. For the MERS datasets, for example, we found only five reports published with accessible raw data, but one report had several patients with incubation times ranged from 0 to 21 days. It is unclear whether these data were included in the other datasets. If these data are included in the analysis, it significantly impacts the outcome for estimation of incubation times 7.5 (7.1-7.9) days ( Figure S1) Thus, access to well-annotated data related to these topics from clinical patients and subclinical subjects will help our understanding for each of these factors. Our results indicate that the current 14 days isolation period should be continued until more comprehensive data are available. To this end, we make the following suggestions: 1. Data should be ideally annotated using standard metadata tags, for example, from the Disease Ontology (disease-ontology.org) to aid data standardization, integration, and analysis. infected individuals, but also the samples from the "normal" population. Clinicians can help support these efforts by carefully collecting and capturing as much relevant patient data where possible. In this way, more complete datasets can be constructed, allowing for more in-depth analyses to better determine optimal intervention strategies and patient treatment. A novel coronavirus from patients with pneumonia in China A pneumonia outbreak associated with a new coronavirus of probable bat origin Clinical features of patients infected with 2019 novel coronavirus in Wuhan National Health Commission of the People's Republic of China A novel coronavirus emerging in China-Key questions for impact assessment Early transmission dynamics in Wuhan, China, of novel coronavirus-infected pneumonia Incubation periods of acute respiratory viral infections: a systematic review MERS transmission and risk factors: a systematic review The incubation period of 2019-nCoV infections among travellers from Wuhan, China. medRxiv Does SARS-CoV-2 has a longer incubation period than SARS and MERS?