The term “new china virus” is a colloquialism for a pathogen officially designated as Severe Acute Respiratory Syndrome Coronavirus 2, or SARS-CoV-2. This virus is the causative agent of the disease known as COVID-19. The name points to its initial detection in China, but scientific naming conventions aim for geographically and culturally neutral terms to prevent stigma.
Identification and Naming
In late 2019, health authorities in Wuhan, China, detected a cluster of pneumonia cases with no clear cause. By early January 2020, scientists had isolated and genetically sequenced a novel coronavirus. This was a new strain in a family of viruses known for causing illnesses ranging from the common cold to more severe diseases.
The International Committee on Taxonomy of Viruses (ICTV) is responsible for naming viruses based on their genetic structure. On February 11, 2020, the ICTV named the virus SARS-CoV-2, as genetic analysis revealed it was related to the coronavirus that caused the 2003 SARS outbreak. On the same day, the World Health Organization (WHO) named the disease COVID-19, an acronym for Corona-Virus-Disease-2019. The distinction between the virus (SARS-CoV-2) and the disease (COVID-19) is a standard practice, similar to how HIV is the virus that causes AIDS.
Viral Structure and Transmission
SARS-CoV-2 is an RNA virus, meaning its genetic material is ribonucleic acid. It belongs to the large family of coronaviruses, so-named for the crown-like spikes that protrude from their surface. These spike proteins are fundamental to the virus’s ability to infect human cells. The tips of these spikes bind specifically to a protein on the surface of human cells called angiotensin-converting enzyme 2 (ACE2). ACE2 receptors are abundant on cells in the lungs, arteries, heart, kidney, and intestines, which explains the virus’s wide-ranging effects.
Once the spike protein latches onto an ACE2 receptor, the viral and cell membranes fuse, allowing the virus to release its RNA genome into the cell. The infected cell’s own machinery is then hijacked, forced to read the viral RNA and produce new viral components. These components assemble into new virus particles, which are then released to infect other cells, continuing the cycle of infection.
The primary way SARS-CoV-2 moves from person to person is through the air. When an infected person breathes, talks, coughs, or sneezes, they release respiratory fluids. These fluids can be larger droplets that fall quickly or smaller aerosol particles that can remain suspended in the air for longer periods and travel farther. Inhaling these infectious particles is the main route of transmission.
Another potential route of transmission is through contact with contaminated surfaces, known as fomites. This occurs if a person touches a contaminated surface and then their own mouth, nose, or eyes. However, scientific consensus indicates that this method of transmission is significantly less common than airborne inhalation.
The Course of a COVID-19 Infection
After SARS-CoV-2 enters the body, there is an incubation period before symptoms appear. This period typically lasts from two to 14 days, with an average of about five to six days. During this time, the virus is replicating, primarily in the cells lining the respiratory tract. An infected person can be contagious during this phase, even without showing any signs of illness.
The symptoms of COVID-19 are diverse and can range from very mild to severe. Common early symptoms include fever, a dry cough, fatigue, and a loss of taste or smell. Some individuals may also experience sore throat, headache, muscle aches, or gastrointestinal issues. For many, the illness does not progress beyond this stage, and they recover within a couple of weeks.
In more severe cases, the infection can lead to pneumonia as the virus damages the air sacs (alveoli) in the lungs, causing them to fill with fluid and inflammatory cells. This inflammation impedes oxygen from passing into the bloodstream, causing shortness of breath and low blood oxygen levels. This condition can progress to Acute Respiratory Distress Syndrome (ARDS), a form of lung failure that often requires mechanical ventilation.
The body’s own immune response can sometimes contribute to the severity of the disease. In some patients, the immune system overreacts to the virus in a phenomenon known as a “cytokine storm.” This massive release of inflammatory molecules, called cytokines, can cause widespread inflammation and damage organs beyond the lungs, including the heart, kidneys, and brain. This systemic inflammation is a cause of the most severe complications of COVID-19.
Scientific Countermeasures
A primary focus was the creation of vaccines. Technologies like messenger RNA (mRNA) and viral vectors were utilized to develop vaccines with unprecedented speed. These vaccines work by introducing a harmless piece of the virus’s genetic code, specifically the part that codes for the spike protein, to the body’s cells. This genetic instruction prompts the cells to produce copies of the spike protein. The immune system then recognizes these proteins as foreign and generates a protective response, creating antibodies and memory cells. This process prepares the immune system to quickly recognize and neutralize the actual SARS-CoV-2 virus if it enters the body in the future, preventing or reducing the severity of illness.
Studies have shown that wearing high-quality, well-fitting masks effectively reduces the transmission of respiratory droplets and aerosols. Improving indoor ventilation, either by opening windows or using air filtration systems, helps to disperse and remove virus particles from the air, lowering the risk of transmission in shared spaces.