1. What is Corona Virus?
Coronavirus (CoV) is a small spherical enveloped RNA virus of the genus "Dependovirus", in the family "Picornaviridae". Members of this genus are known as "coronaviruses" or simply "cov". The coronavirus genome comprises 10,849 bases and encodes at least three proteins: C (structural), E (phospho-ethanolamine transferase precursor), and M (nonstructural). To date, only one serotype has been identified.
2. Where did it come from?
Coronavirus was first identified in 1953 by Drs. David Baltimore and Joseph Smadel at Walter Reed Army Institute of Research. Initial studies of the virus indicated that it was fairly benign and did not cause any obvious disease in humans or animals.
3. Is it contagious?
The spread of infection to close contacts is through respiratory secretions such as saliva, sputum, or nasal mucus. This does not require physical contact or substantial exposure amounting to aerosolization/viral shedding from an infected host. The time frame for transmissibility ranges from 8-12 days before symptoms appear until 2-5 days after symptoms begin. Patients are only infectious once they have developed symptoms, which include fever, cough, runny nose, headache, sore throat, along myalgia, diarrhea, vomiting, and stomach ac.
4. What are the reactions to it?
The incubation period is about 2-10 days (average 5). Symptoms typically occur in two phases: initially, a nonspecific respiratory illness resembling influenza, and second, either mild viral pneumonia or a more severe progressive respiratory illness requiring hospitalization and supportive therapy. The clinical disease caused by this virus is rarely fatal; however, a secondary bacterial infection of the respiratory tract may lead to acute respiratory distress syndrome (ARDS), which is often fatal.
5. How is CoV diagnosed?
Diagnosis can be made on clinical specimens using molecular techniques such as real-time RT-PCR assays capable of detecting all known human coronaviruses. A number of these assays have been commercialized and distributed in the U.S. and other countries by governmental agencies and commercial companies such as BD, Meridian Bioscience/Taqman, Cepheid, and others. The CDC coronavirus surveillance program (CoVSP) provides real-time RT-PCR assays for testing of upper respiratory specimens from symptomatic outpatients with acute respiratory illness at any location in the U.S.
6. Can it be treated?
There is no specific treatment for CoV; aspirin should be avoided until a diagnosis of secondary bacterial infection (e.g., pneumonia) has been excluded because salicylates may induce severe bronchospasm or exacerbate preexisting myocardial damage in patients coinfected with coronavirus and bacteria.
7. How common is CoV?
CoV infections are not uncommon, although most adult cases are subclinical. Subclinical human coronavirus infection represents the most common mode of natural transmission of these viruses with person-to-person spread occurring via close contact or through the air by large respiratory droplets that result from coughing or sneezing. Infections most commonly occur during winter months when there is close contact between family members and friends at home, school, work, and social functions. Transmission does not require physical contact with an infected individual; it may be transmitted via self-inoculation with respiratory secretions (e.g., hand to nose/mouth). This largely explains why community outbreaks can occur in closed environments such as hospitals, nursing homes, and dormitories.
8. Why is it dangerous?
In severely immunocompromised patients, the severe respiratory disease may be a more prominent presentation of CoV infection with CoV being involved in 10-20% of the cases of acute respiratory failure requiring non-elective intubation and mechanical ventilation in these hosts. In this population, lack of response to antibiotic therapy is common because virus replication overwhelms the host's immune system leading to systemic viral dissemination; drugs that interfere with virus replication (e.g., ribavirin) are often used in hospitalized patients but were not effective alone or even in combination with interferon-alpha for the treatment of acute lower respiratory tract infection caused by the SARS-CoV.
9. Has there ever been a vaccine?
No vaccines are available for human coronaviruses. However, DNA vaccines against the enzootic subgroup C viruses (eastern equine encephalitis virus and porcine respiratory and reproductive syndrome virus) were shown to induce neutralizing antibodies that cross-protected mice against challenge with the virulent virus; this result is encouraging, but the additional study will be needed before initiation of human clinical trials.
10. How likely is it to cause a public health problem?
The low mortality rate associated with CoV infections in immunocompetent hosts is reassuring; however, novel viruses may emerge as pandemic threats in the future if they acquire genetic or antigenic alterations that favor human-to-human transmission or enhance the ability to cause severe disease in immunocompetent hosts.
