Alignment of the full-length genome sequence of the COVID-19 virusand other available genomes of Betacoronavirus showed the closest relationship was with the bat SARS-like coronavirus strain BatCov RaTG13,identity 96%.
Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from patients in different localitieswith symptom onset between the end of December2019 and mid-February2020 showed 99.9% homology, without significant mutation.
Cytopathic effects (CPE) were observed 96 hours after inoculation. Typical crown-like particles were observed under transmission electron microscope (TEM) with negative staining. The cellular infectivity of the isolated viruses could be completely neutralized by the sera collected from convalescent patients. Transgenic human ACE2 mice and Rhesus monkey intranasally challenged by this virus isolate induced multifocal pneumonia with interstitial hyperplasia.The COVID-19 virus was subsequently detected and isolated in the lung and intestinal tissues of the challenged animals.
Тhe COVID-19 virus is unique among human coronaviruses in its combination of high transmissibility, substantial fatal outcomes in some high-risk groups, and ability to cause huge societal and economic disruption.
Among 55,924 laboratory confirmed cases reported as of 20 February2020, the median age is 51years (range 2 days-100years old; IQR 39-63 years old) with the majority of cases (77.8%)aged between 30–69 years. Among reported cases, 51.1% are male, 77.0% are from Hubeiand 21.6% are farmers or laborersby occupation.
Based on the epidemiologic characteristics observed so farin China, everyone is assumed to be susceptible, although there may be risk factors increasing susceptibility to infection.
At some point early in the outbreak, some casesgenerated human-to-human transmission chains that seeded the subsequent community outbreak... a relatively high R0 of 2-2.5
As of 20 February2020, there were 2,055COVID-19 laboratory-confirmed cases reported among HCW (медперсонал) from 476 hospitals across China. The majority of HCW cases (88%) were reported from Hubei
more than 40,000 HCW have been deployed from other areas of China to support the response in Wuhan. Аmong the HCW infections, most were identified early in the outbreak in Wuhan when supplies and experience with the new disease was lower.
There have been reports of COVID-19 transmissionin prisons(Hubei, Shandong, and Zhejiang, China), hospitals (as above)and in a long-term living facility.
Data on individuals aged 18years old and under suggest that there is a relatively low attack rate in this age group (2.4% of all reported cases)
Symptoms of COVID-19 are non-specific and the disease presentation can range from no symptoms (asymptomatic) to severe pneumonia and death. As of 20 February 2020 and 12based on 55924 laboratory confirmed cases, typical signs and symptoms include:fever (87.9%), dry cough (67.7%), fatigue (38.1%), sputum production (33.4%), shortness of breath (18.6%), sore throat (13.9%), headache (13.6%), myalgiaor arthralgia (14.8%), chills(11.4%), nausea or vomiting (5.0%), nasal congestion (4.8%), diarrhea (3.7%), and hemoptysis (0.9%), and conjunctival congestion (0.8%).
People with COVID-19 generally develop signs and symptoms,including mild respiratory symptoms and fever, on an average of 5-6 days after infection (mean incubation period 5-6 days, range 1-14 days).
Most people infected with COVID-19 virus have mild disease and recover. Approximately 80% of laboratory confirmed patients have had mild to moderatedisease, which includes non-pneumonia and pneumonia cases, 13.8% have severe disease (dyspnea, respiratory frequency ≥30/minute, blood oxygen saturation≤93%, PaO2/FiO2 ratio <300, and/or lung infiltrates >50% of the lung field within 24-48 hours) and 6.1% are critical (respiratory failure, septic shock, and/or multiple organ dysfunction/failure). Asymptomatic infection has been reported, but the majority of the relatively rare cases who are asymptomatic on the date of identification/report went on to develop disease. The proportion of truly asymptomatic infections is unclear but appears to be relatively rare.
Individuals at highest riskf or severe disease and death include people aged over 60 years and those with underlying conditions such as hypertension, diabetes, cardiovascular disease, chronic respiratory disease and cancer.
As of 20February, crude fatality ratio[CFR2]- 3.8%. The overall CFR varies by locationand intensity of transmission (i.e. 5.8%in Wuhanvs.0.7%in other areas in China). In China, the overall CFR was higher in the early stages of the outbreak (17.3% for cases with symptom onset from 1-10 January) and has reduced over time to 0.7% for patients with symptom onset after 1 February. The Joint Mission noted that the standard of care has evolved over the course of the outbreak. Based on available information, the median time from symptom onset to laboratory confirmation nationally decreased.This has allowedf or earlier case and contact identification, isolation and treatment.
The CFR is higher among males compared to females (4.7% vs. 2.8%).
the median time from onset to clinical recovery for mild cases is approximately 2 weeks and is 3-6 weeks for patients with severe or critical disease. Preliminary data suggests that the time period from onset to the development of severe disease, including hypoxia, is 1 week. Among patients who have died, the time from symptom onset to outcome ranges from 2-8 weeks.
The prevention and control measures have been implemented rapidly,from the early stages in Wuhan and other key areas of Hubei,to the current overall national epidemic.
Measures were taken to ensure that all cases were treated, and close contacts were isolated and put under medical observation. Other measures implemented included the extension of the Spring Festival holiday, traffic controls, and the control of transportation capacity to reduce the movement of people;mass gathering activities were also cancelled. Information about the epidemic and prevention and control measures was regularly released. Public risk communications and health education were strengthened; allocation of medical supplies was coordinated, new hospitals were built, reserve beds were used and relevant premises were repurposed to ensure that all cases could be treated; efforts were made to maintain a stable supply of commodities and their prices to ensure the smooth operation of society
the focus was on patient treatment and the interruption of transmission, with an emphasis on concrete steps to fully implement relevant measures for the testing, admitting and treating of all patients. New technologies were applied such as the use of big data and artificial intelligence (AI) to strengthen contact tracing and the management of priority populations. Relevant health insurance policies were promulgated on "health insurance payment, off-site settlement, and financial compensation" All provinces provided support to Wuhan and priority areas in Hubei Province in an effort to quickly curb the spread of the diseaseand provide timely clinical treatment. Pre-school preparation was improved, and work resumed in phases and 16batches. Health and welfare services were provided to returning workers in a targeted and ‘one-stop’ manner. Normal social operations are being restored in a stepwise fashion; knowledge about disease prevention is being popularized to improve public health literacy and skills; and a comprehensive program of emergency scientific research is being carried out to develop diagnostics, the rapeuticsand vaccines,delineate the spectrum of the disease,and identify the source of the virus.
The remarkable speed with which Chinese scientists and public health experts isolated the causative virus, established diagnostic tools, and determined key transmission parameters,such as the route of spread and incubation period, provided the vital evidence base for China’s strategy, gaining invaluable time for the response.
the Joint Mission estimates that this truly all-of-Government and all-of-society approach that has been taken in China has averted or at least delayed hundreds of thousands of COVID-19 cases in the country. By extension, the reduction that has been achieved in the force of COVID-19 infection in China has also played a significant role in protecting the global communityand creating a stronger firstline of defense against international spread.
China’s uncompromising and rigorous use of non-pharmaceutical measures to contain transmission of the COVID-19 virus in multiple settings provides vital lessons for the global response.
Much of the global community is not yet ready, in mindset and materially, to implement the measures that have been employed to contain COVID-19 in China. These are the only measures that are currently proven to interrupt or minimize transmission chains in humans. Fundamental to these measures is extremely proactive surveillance to immediately detect cases, very rapid diagnosis and immediate case isolation, rigorous tracking and quarantine of close contacts, and an exceptionally high degree of population understanding and acceptance of these measures.
Achieving the high quality of implementation needed to be successful with such measures requires an unusual and unprecedented speed of decision-making by top leaders, operational thoroughness by public health systems, and engagement of society. Given the damage that can be caused by uncontrolled, community-level transmission of this virus, such an approach is warranted to save lives and to gain the weeks and months needed for the testing of therapeutics and vaccine development. The time that can be gained through the full application of these measures –even if just days or weeks –can be invaluable in ultimately reducing COVID-19 illness and deaths.
COVID-19 is spreading with astonishing speed; COVID-19 outbreaks in any setting have very serious consequences; and there is now strong evidence that non-pharmaceutical interventions can reduce and even interrupt transmission.