COVID-19 – Introduction
On February 11, 2020 the World Health Organization named the disease COVID-19. Coronavirus (COVID-19) is a respiratory illness caused by a new virus. Symptoms range from a mild cough to pneumonia. Some people recover easily, others may get very sick very quickly. There is evidence that it spreads from person to person. People with coronavirus may experience fever flu-like symptoms such as coughing, sore throat and fatigue shortness of breath. The virus is most likely spread through close contact with an infectious person contact with droplets from an infected person’s cough or sneeze touching objects or surfaces (like doorknobs or tables) that have cough or sneeze droplets from an infected person, and then touching your mouth or face. It’s very unlikely it can be spread through things like packages or food. There is no treatment for coronavirus, but medical care can treat most of the symptoms. Antibiotics do not work on viruses. Wash your hands with soap and water often – do this for at least 20 seconds. Always wash your hands when you get home or into work. Use hand sanitiser gel if soap and water are not available. Cover your mouth and nose with a tissue or your sleeve (not your hands) when you cough or sneeze. Put used tissues in the bin straight away and wash your hands afterward. Try to avoid close contact with people who are unwell. Do not touch your eyes, nose or mouth if your hands are not clean. Stay at home. Not go to work, school or public places. Not use public transport or taxis. Do this for up to 14 days to help reduce the possible spread of infection. [SOURCE: Govt of China/Australia/UK]
In the Beginning
At the end of December 2019, the Wuhan Municipal Health Commission reported the outbreak of viral pneumonia caused by an unknown pathogen in Wuhan, China. Subsequently, the unknown pathogen was identified as a novel coronavirus denoted as 2019-nCoV by the World Health Organization (WHO) on 10 January 2020. On 12 and 13 January 2020, the full genomic sequence of 2019-nCoV, denoted WIV04 strain (GISAID accession no. EPI_ISL_402124), was released, with about 82% homology to that of SARS-CoV Tor2 (GenBank accession no. AY274119)
Identification of an emerging coronavirus
Identification of pathogens mainly includes virus isolation and viral nucleic acid detection. According to the traditional Koch’s postulates, virus isolation is the “gold standard” for virus diagnosis in the laboratory. First, viral culture is a prerequisite for diagnosing viral infections. A variety of specimens (such as swabs, nasal swabs, nasopharynx or trachea extracts, sputum or lung tissue, blood and feces) should be retained for testing in a timely manner, which gives a higher rate of positive detection of lower respiratory tract specimens. Then, immunological methods – including immunofluorescence assay, protein microarray, direct fluorescent antibody assay, MAb-based rapid NP (nucleocapsid protein) detection, semiconductor quantum dots, and the microneutralization test – which measure binding between the antigen from the whole virus or protein of the coronavirus and corresponding antibody, are easy to operate rapidly but have a lower sensitivity and specificity.
Etiology and pathogenesis
The 2019-nCoV isolated from the lower respiratory tract of patients with unexplainable pneumonia in Wuhan, and it is a novel coronavirus belonging to the β genus. The 2019-nCoV has an envelope; its particles are round or oval, often polymorphic, with a diameter from 60 nm to 140 nm. Its genetic characteristics are significantly different from SARSr-CoV (SARS related coronaviruses) and MERSr-CoV (MERS related coronaviruses). Current research shows it has more than 85% homology with SARSr-CoV (bat-SL-CoVZC45). 2019-nCoV can be found in human respiratory epithelial cells 96 h after in vitro isolation and culture, while it takes about 6 days in VeroE6 or Huh-7 cell lines
No evidence of viral mutation has been found so far. It is necessary to obtain much more clinically isolated viruses with time and geographical variety to assess the extent of the virus mutations, and also whether these mutations indicate adaptability to human hosts
fever, imaging features of pneumonia, normal or reduced white blood cell count, or reduced lymphocyte count in the early stages of the disease onset.
Those with one of the following pathogenic evidence is the confirmed case:
(1) positive for the 2019-nCoV by the real-time PCR test for nucleic acid in respiratory or blood samples
2) viral gene sequencing shows highly homogeneity to the known 2019-nCoV in respiratory or blood samples
Persons with close contacts and suspicious exposure should be advised to have a 14-day health observation period, which starts from the last day of contact with the 2019-nCoV infected patients or suspicious environmental exposure. Once they display any symptoms, especially fever, respiratory symptoms such as coughing, shortness of breath, or diarrhea, they should reach out for medical attention immediately. Contact surveillance should be carried out for those who had exposed to accidental contact, low-level exposure to suspected or confirmed patients, i.e. checking any potential symptoms when carrying out daily activities.
Criteria to define patients with suspected mild symptoms
1 In-home isolation and care after assessment by doctor (golden standard)
2 With a fever < 38 ℃
3 The fever can go down by itself
4 No dyspnea, no asthma
5 With or without cough
6 No underlying chronic diseases, e.g.: heart, lung and kidney diseases
Detection of pathogens in the respiratory tract
Flu antigens. At present, routinely detected flu antigens are A, B, and H7N-subtypes. Sampling of throat swabs is conducive to early rapid screening for flu because of the fast test, but it has a relatively high false negative rate.
Respiratory virus nucleic acid. The detection of respiratory virus nucleic acid is commonly used to detect the infection by other common respiratory viruses, mycoplasma and chlamydia infection, such as adenovirus, parainfluenza virus, respiratory syncytial virus, mycoplasma, chlamydia, influenza A and influenza B virus, etc.
2019-nCoV nucleic acid detection. Accurate RNA detection of 2019-nCoV is with diagnostic value (Strong recommendation). The RNA of 2019-nCoV positive in the throat swab sampling or other respiratory tract sampling by fluorescence quantitative PCR method, especially that from multiple samples and detection kits, excluding sample quality, sample collection time, contaminatory and technical problems, is of great support for etiological diagnosis.
Incubation and contagious period
Based on currently epidemiological survey, the latency period is generally from 3 to 7 days, with a maximum of 14 days . Unlike SARSr-CoV, 2019-nCoV is contagious during the latency period.
The virus that causes coronavirus disease 2019 (COVID-19) is stable for several hours to days in aerosols and on surfaces, according to a new study from National Institutes of Health, CDC, UCLA and Princeton University scientists in The New England Journal of Medicine. The scientists found that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was detectable in aerosols for up to three hours, up to four hours on copper, up to 24 hours on cardboard and up to two to three days on plastic and stainless steel. The was performed at about room temperature, 21-23 degrees Celsius. The results provide key information about the stability of SARS-CoV-2, which causes COVID-19 disease, and suggests that people may acquire the virus through the air and after touching contaminated objects. The study information was widely shared during the past two weeks after the researchers placed the contents on a preprint server to quickly share their data with colleagues.
The scientists, from the National Institute of Allergy and Infectious Diseases(USA), Montana facility at Rocky Mountain Laboratories, compared how the environment affects SARS-CoV-2 and SARS-CoV-1, which causes SARS. SARS-CoV-1, like its successor now circulating across the globe, emerged from China and infected more than 8,000 people in 2002 and 2003. SARS-CoV-1 was eradicated by intensive contact tracing and case isolation measures and no cases have been detected since 2004. SARS-CoV-1 is the human coronavirus most closely related to SARS-CoV-2. In the stability study the two viruses behaved similarly, which unfortunately fails to explain why COVID-19 has become a much larger outbreak.
STUDY OF THE NATIONAL HEALTH INSTITUTE
The National Institute of Health( USA) study attempted to mimic virus being deposited from an infected person onto everyday surfaces in a household or hospital setting, such as through coughing or touching objects. The scientists then investigated how long the virus remained infectious on these surfaces.
The scientists highlighted additional observations from their study:
If the viability of the two coronaviruses is similar, why is SARS-CoV-2 resulting in more cases? Emerging evidence suggests that people infected with SARS-CoV-2 might be spreading virus without recognizing, or prior to recognizing, symptoms. This would make disease control measures that were effective against SARS-CoV-1 less effective against its successor.
In contrast to SARS-CoV-1, most secondary cases of virus transmission of SARS-CoV-2 appear to be occurring in community settings rather than healthcare settings. However, healthcare settings are also vulnerable to the introduction and spread of SARS-CoV-2, and the stability of SARS-CoV-2 in aerosols and on surfaces likely contributes to transmission of the virus in healthcare settings.
The findings affirm the guidance from public health professionals to use precautions similar to those for influenza and other respiratory viruses to prevent the spread of SARS-CoV-2:
- Wash your hands often with soap and water for at least 20 seconds, especially after going to the bathroom; before eating; and after blowing your nose, coughing, or sneezing.
- If soap and water are not readily available, use an alcohol-based hand sanitizer with at least 60% alcohol. Always wash hands with soap and water if hands are visibly dirty.
- Avoid close contact with people who are sick.
- Avoid touching your eyes, nose, and mouth.
- Stay home when you are sick.
- Cover your cough or sneeze with a tissue, then throw the tissue in the trash.
- Clean and disinfect frequently touched objects and surfaces using a regular household cleaning spray or wipe.
- Symptomatic treatment of fever. When the temperature is higher than 38.5 ℃, ibuprofen can be used for antipyretic (oral, 0.2 g per time, it can be used every 4–6 h in continuous fever, but no more than 4 times in 24 h), and the temperature below 38 ℃ is acceptable. Much lower body temperature is not conducive to antiviral treatment.
- The patient should be monitored for blood routine, CRP, PCT, organ function (liver enzyme, bilirubin, myocardial enzyme, creatinine, urea nitrogen, Urine volume, etc.), coagulation function, arterial blood gas analysis and chest imaging.
- Reduce the secretion of lung glands and improve the respiratory function. For patients with dyspnea, cough, wheeze, and respiratory distress syndrome due to the increased respiratory gland secretion, it is recommended to use selective (M1, M3) receptor anticholinergic drugs to reduce the secretion, relax the smooth muscle in airway, relieve airway spasm and improve the pulmonary ventilation.
- The patient should be given effective oxygen therapy, including nasal catheter, mask oxygen, high flow nasal oxygen therapy (HFNO), non-invasive ventilation (NIV) or invasive mechanical ventilation
- According to the clinical manifestations of patients, if the accompanying bacterial infection cannot be ruled out, mild patients can take antibacterial drugs against community-acquired pneumonia, such as amoxicillin, azithromycin, or fluoroquinolones; empirical antibacterial treatment in severe patients should cover all possible pathogens, deescalating therapy until the pathogenic bacteria are clarified.
Source: the WHO (https://www.who.int/), CDC (Centers for Disease Control and Prevention, https://www.cdc.gov/), NICE (National Institute for Health and Clinical Excellence, https://www.nice.org.uk/), National Health Commission of the People’s Republic of China (http://www.nhc.gov.cn/), and National Administration of Traditional Chinese Medicine (http://www.satcm.gov.cn/).