Emergence
The coronavirus first emerged in late-December 2019 in Wuhan, China. As it began spreading into nearby regions, the government of China locked down the city, quarantining about 11 million people in Wuhan. Over the days, it went on to include almost 60 million people in the province of Hubei.
The lockdown meant industrial operations in the coronavirus hotspot were stopped. Travel restrictions were placed within China meant that air, rail and road traffic were paused or scaled back across some regions.
It was in early 2020 that the World Health Organization (WHO) identified virus SARS-CoV-2. The outbreak quickly spread around the world.
Coronavirus
Coronavirus (named for the crownlike spikes on its surface) is a common type of virus and is a member ofCoronavirinaea subfamily of the Coronaviridaefamily. It causes a respiratory infection—in the nose, sinuses, or upper throat. Most coronaviruses aren’t dangerous. Some coronaviruses infect people, birds and animals.
Types
Coronaviruses were first identified in the 1960s.
7 types of coronavirus are recognised that can infect humans.
The common types are:
- 229E (alpha coronavirus)
- NL63 (alpha coronavirus)
- OC43 (beta coronavirus)
- HKU1 (beta coronavirus)
These cause mild to moderate respiratory infections, like the common cold. Rarer strains that cause more severe complications include MERS-CoV, which causes Middle East respiratory syndrome (MERS), and SARS-CoV, the virus responsible for the severe acute respiratory syndrome (SARS).
The SARS-CoV-2, a new type of coronavirus found recently, is one of the types of coronaviruses. It’s called ‘novel coronavirus’— referring to a new coronavirus type that has not been previously identified. It has been named by the International Committee on Taxonomy of Viruses.
A Chinese study of 103 COVID-19 cases found 2 strains of SARS-CoV-2, which they named L and S. While the S type is older, it was the L type that was more commonly found in the early stages of the outbreak. It may be that one may cause more cases of the disease than the other.
Infections
Coronaviruses will infect most people at some time or other during their lifetime.
The coronaviruses utilise animals as their primary hosts and some infect humans too. The forerunners of the SARS, as well as the MERS coronaviruses, have been traced in bats. The SARS virus is said to have first infected bats, then civets (small, nocturnal mammals) and then infected people, while MERS infected camels before spreading to humans. Evidence suggests that the novel coronavirus of 2019 spread from bats to humans after perhaps passing through an intermediate carrier. However, the most common human coronaviruses — named 229E, NL63, OC43 and HKU1 — affect humans as their natural hosts (they do not affect animals first and then pass on to humans).
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Box
SARS and MERS
SARS (Severe acute respiratory syndrome) , a contagious disease that leads to a life-threatening form of pneumonia, develops after infection with the SARS-CoV coronavirus. It began spreading in November 2002, after appearing in the Guangdong Province in southern China. It spread to Hong Kong and then around the world, causing infections in over 24 countries. It came to a halt in terms of wide-spreading in July of 2003.
SARS-CoV infects the upper and lowers respiratory tracts. Its symptoms develop over a week. It starts with a fever and then people develop flu-like symptoms, including dry coughing, chills, diarrhoea, breathlessness and aches. After pneumonia, in most cases, it causes failure of the lungs, heart, or liver at the advanced stage.
The 2002 outbreak led to over 8,098 people contracting SARS, of which 774 infections were fatal (a mortality rate of 9.6 per cent). Cases of SARS have not been reported since 2015. Interestingly, like in the case of COVID-19, in SARS too complications were more likely in older adults. According to one set of data, over half of those who died from the infection were above 60-65 years of age.
MERS (Middle East respiratory syndrome), which was first detected in Saudi Arabia and began to affect humans in 2012, is attributed to the coronavirus MERS-CoV. As the name suggests, it is an illness that severely affects the respiratory system. Since then, it has spread to other countries. About 858 people have died from MERS. The largest outbreak of MERS outside of the Arabian Peninsula took place in South Korea in May 2015.
Symptoms of this disease are fever, coughing and breathlessness. It, like others, spreads through close contact with people who already have an infection. According to a study conducted in 2019, the disease is fatal in 30-40 per cent of people who contract it.
Box ends
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COVID-19 Infection
‘COVID-19’ is the name of the disease caused by the novel member of the coronavirus family, SARS-CoV-2, that emerged in 2019. SARS-CoV-2 spreads the same way other coronaviruses do, mainly through person-to-person contact. Breaking down the abbreviation COVID-19, we have CO for corona; VI for the virus; and D for disease; while 19, of course, indicates the year of its discovery.
COVID-19 infection may affect the upper respiratory tract (the nose, throat, the sinuses) or the lower respiratory tract (windpipe and lungs). Infections range from mild to serious. Symptoms of COVID-19, caused by the new coronavirus SARS-CoV-2, include respiratory illness with fever, cough, and difficulty breathing.
Causes
Researchers aren’t sure what caused it. There’s more than one coronavirus, and they are commonly found in humans as well as in animals such as bats, cattle, camels, and cats. As stated, SARS-CoV-2, the virus that causes COVID-19, is similar to MERS and SARS. It is said that they all come from bats. It was found that many people who were infected by COVID-19early on had some connection to a live seafood and animal market in China, commonly termed a “wet market.” Though it is suggested that the virus may have come from animals sold in the market, there have been reports of scientists in China involved in research on bats—in fact, very close to the market in Wuhan to which place the virus has been traced and at about the same time.
Transmission
Researchers believe that the viruses transmit via fluids in the respiratory system, such as mucus (respiratory droplets that infected people expel when they breathe, cough or sneeze). The transmission rate is relatively high. There have been various findings on the range of the spread of the infection. While one research has estimated that one infected person can transmit the disease to between 2 and 2.5 others, another study estimated a higher rate – one case transmitting the infection to 4.7 to 6.6 persons. A person suffering from seasonal flu, in comparison, is likely to pass it to between 1.1 and 2.3 other persons.
Coronaviruses can spread in the following ways:
- Coughing and sneezing without covering the mouth which can lead to dispersal of the droplets into the air.
- Coming in physical contact (touching or shaking hands) with a person who has the virus can pass it between individuals.
- It can spread through contact with a surface or object that has the virus (touching it and then the nose, eyes, or mouth can spread it).
- Some animal coronaviruses, such as feline coronavirus, may spread through contact with faeces. However, it is not clear whether or not this also applies to human coronaviruses.
To prevent transmission, therefore, people should not come in close contact with each other when the virus is spreading. Staying at home and resting while the symptoms are active is the best means of safeguard.
Covering the mouth and nose with a tissue or handkerchief while coughing or sneezing is most important to prevent transmission. It is important to dispose of any tissues after use and maintain proper hygiene in general, but simple measures — such as washing your hands, disinfecting frequently touched surfaces and objects, and avoiding touching your face, eyes and mouth — can greatly lower risk of infection.
Wearing cloth face masks in public places is seen as necessary where it is difficult to maintain a 6-foot (2-metres) distance from others. This is likely to slow down the transmission of the virus from asymptomatic carriers of the virus and people who are not aware of having contracted it. Surgical masks and N95 respirators are generally reserved for healthcare workers.
One is likely to get COVID-19 from people but the virus can also spread from surfaces of goods like packages, groceries, or food. Most viruses are capable of surviving for some hours on the surface on which they land, but generally, they cannot do so for long outside a living host. Research shows that SARS-CoV-2 is different: it can last for several hours on various types of surfaces including copper (4 hours), cardboard (up to 24 hours) and plastic or stainless steel (up to 2 to 3 days). In fact, scientists are not quite clear about exactly how long this virus can survive outside a live host. People can pick up a coronavirus from a contaminated surface at least for a short window of time. Thus, it is of utmost importance that surfaces are disinfected to be free of the virus. One should wipe down plastic, metal, or glass packaging with soap and water. The coronavirus can linger on hard surfaces, so it is sensible to clean and disinfect countertops and anything else one’s bags or hands have touched in case one has gone shopping. The insistence on cleaning surfaces or goods purchased is important, as the virus may be lurking on the materials.
Scientists cannot clearly say what is the mortality rate of this disease as it is not certain how many people have become infected (it takes time from being infected and expression of the infection to treatment and death). But it is most dangerous for elderly people and those with pre-existing health burdens. In March, it was stated that some 3.4 per cent of all patients may have died (WHO). Those above 80 years of age had a high fatality rate of 14.8 per cent, dropping to 8 and 3 per cent in 70-79 and 60-69 age groups respectively.
Risk Factors
While COVID-19 can infect anyone, most infections are usually mild, especially in children and young adults. But if one is not in an area where COVID-19 is spreading, one has not travelled from an area where it’s spreading, and one has not been in contact with someone who has it, the risk of infection is low.
People most at risk of getting seriously affected by the infection are those above 65 years of age, those who live in nursing homes, those with weak immune systems, and those with medical conditions such as hypertension, diabetes, heart disease, lung disease, asthma, liver disease, kidney disease that needs dialysis, and those undergoing cancer treatment, especially chemotherapy, or those who smoke.
Structure and Working of the Virus
Coronaviruses have spiky projections on their outer surfaces that resemble the points of a crown (‘corona’). Beneath the virus’ pronged exterior is a round core that contains genetic material that the virus can inject into vulnerable cells to infect them. These are ‘spike’ proteins that extend from within the core to the viral surface and allow the virus to recognize and latch onto specific cells in the body. It has a “greasy” membrane.
Researchers say that the spike engages its receptor [on a host cell], and a cascade is triggered, and the virus mergers with the cell. This union allows the virus to release its genetic material and attack the cell. Then the virus sheds its coat and new viruses grow in the cell.
An idea is that the coronaviruses presumably are tuned to maximise spread amongst the population rather than pathogenicity, i.e., harm their human host.
Symptoms
Coronaviruses affecting humans typically cause a respiratory infection with mild to severe flu-like symptoms, but the exact symptoms vary depending on the type of coronavirus.
The 4 common human coronaviruses can cause people to develop a runny nose, headache, cough, sore throat and fever. In some individuals, like patients with cardiopulmonary disease or a weakened immune system, the viral infection can progress to a more severe lower-respiratory infection like bronchitis or pneumonia.
Severe MERS and SARS infections generally progress to pneumonia, apart from both causing fever; then there are chills and body aches (SARS) and coughing and shortness of breath (MERS).
The novel coronavirus (COVID-19) causes symptoms similar to those of other coronaviruses: fever, cough and difficulty breathing in most patients. Dizziness, nausea, vomiting and a runny nose are rarer. The appearance of symptoms can occur at any time from 2 days to 14 days. It varies from person to person. The main symptoms include fatigue, chills (sometimes with shaking), body aches, headache, sore throat, loss of smell or taste, and diarrhoea. The virus can lead to pneumonia, respiratory failure, septic shock, as well as strokes. Some people hospitalised for COVID-19 have also had dangerous blood clots in their legs, lungs, and arteries.
A condition known as cytokine release syndrome (or cytokine storm) could lead to complications. In this condition, the immune system is triggered by the infection to pour into the bloodstream cytokines (which are inflammatory proteins) that can kill tissue and damage organs.
Some pointers for the common people are as follows:
- One side of the person’s face may become numb or drooping, and the smile lopsided in severe cases.
- Arms may become weak or numb; when the infected tries to raise both arms, one sags.
- Speechlacks clarity (difficulty in repeating a sentence).
Cold, Flu or COVID-19
COVID-19 can cause symptoms rather similar to those in the case of a bad cold or the flu. But there are differences as well in the symptoms.
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table
| Cold, Flu and COVID-19 | ||||
| Symptom | Cold | Flu |
COVID-19 (ranging from moderate to severe) |
|
| 1.Fever | Rare |
High (100-102 F), Can last 3-4 days |
Common | |
|
2.General pains and aches |
slight |
Usual; many times it is severe |
May occur |
|
|
3.headaches |
rare |
severe |
May occur |
|
|
4.Fatigue and weakness |
Mild |
Intense (may last up to 2-3 weeks) |
May be present |
|
|
5.Extreme exhaustion |
Never |
Usual (starts early) |
Can be present |
|
|
6.Stuffy/runny nose |
Common |
Sometimes present |
Has been reported |
|
|
7.Sneezing |
Usual |
Sometimes |
May occur |
|
|
8.Shortness of breath |
rare |
rare |
In more serious cases only |
|
|
9.Cough |
Mild to moderate |
Common, can become severe |
Common | |
|
10.sore throat |
common |
common |
Has been reported |
|
Unlike the flu, a lot of people do not have a natural immunity to the coronavirus because it’s new. Natural immunity means that the virus, once it attacks, triggers the body to make things called antibodies.
The coronavirus appears to cause higher rates of severe illness and death than the flu, though the symptoms themselves can vary widely from person to person.
Flu is said to be seasonal but flu pandemics have happened year-round. Lab studies have found that higher temperatures and humidity levels might help slow the spread of the new coronavirus, but weather changes by themselves won’t matter much if public health efforts are lacking.
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Sidelight
Community spreads word used by doctors and health officials when they do not know the source of the infection. In the case of COVID-19, it usually refers to a situation in which persons get infected by the virus even though they have not travelled outside the country or known to have been exposed to a person who has travelled abroad or who has been infected by COVID-19.
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Treatment
There’s no specific treatment for COVID-19. People who have a mild infection need the care to ease their symptoms, like getting rest, taking fluids, and taking medication to reduce fever. Over-the-counter medicines can help for a sore throat, body aches, and fever. The WHO made a statement that one shouldn’t take ibuprofen to treat COVID-19 symptoms—this was in March 2020. But they reversed it soon after and said there was no proof that taking it caused any harm.
Antibiotics generally don’t help in viral infections. But if people with COVID-19 are advised to take antibiotics, it could be for an infection that came along with the disease.
Though clinical trials are ongoing to explore treatments used for other conditions that could fight COVID-19 and to develop new treatments, nothing has emerged so far as a course of treatment that would yield required results, especially in serious cases.
Research has focused on remdesivir, an antiviral medication created to control Ebola. An emergency FDA ruling lets doctors use hydroxychloroquine and chloroquine for people with COVID-19 and in clinical trials to study them further. The medications are approved to treat malaria and autoimmune conditions like rheumatoid arthritis and lupus. In June 2020, an antiviral drug Favipiravir was launched by Glenmark Pharmaceuticals under the brand name FabiFlu. This was meant for the treatment of patients suffering from mild to moderate COVID-19. Tocilizumab, a medication used to treat autoimmune conditions, is undergoing clinical trials. And the US FDA is also allowing clinical trials and hospital use of blood plasma from people who have had COVID-19 and recovered to help others build immunity (convalescent plasma). This has been called ‘plasma therapy’.
It is not clear if a person can get re-infected with coronavirus. With other coronaviruses that only cause colds, there is a period during which one is immune, though that immunity goes away after some time.