1 Introduction to COVID-19
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Once you have finished this chapter you should be able to:
- Understand what COVID-19 is.
- Name the cause of COVID-19.
- Explain how COVID-19 is spread.
- Describe who is at greatest risk of COVID-19.
COVID-19 and coronavirus
1-1 What is COVID-19?
COVID-19 is an infectious illness that usually starts suddenly with a cough, sore throat and fever.
1-2 What causes COVID-19?
COVID-19 is caused by a new coronavirus which was first identified in 2019. Therefore COVID-19 stands for coronavirus disease of 2019. The full name of this particular coronavirus is SARS CoV-2. It is the first time humans have been infected with this coronavirus and therefore they have no immunity (protection) to it.
1-3 Where did COVID-19 first appear?
It was first found in China and then spread to other countries. Some coronaviruses can cross over from an animal to cause infection in humans. This coronavirus is believed to have crossed over to humans from bats.
1-4 What is the COVID-19 pandemic?
When COVID-19 first appeared in China it was an epidemic as it only spread locally in the country. Later it spread to many other countries to become a pandemic. Therefore a pandemic is the spread of an infectious disease worldwide.
The spread of coronavirus
1-5 How does coronavirus spread between people?
One of the things which makes this virus so dangerous is that it spreads very quickly between people. There are three important ways that coronavirus can be spread:
- Spread from respiratory droplets: Tiny droplets of saliva or nasal secretion that spray out of a person’s mouth or nose when they cough, sneeze, shout, laugh, sing or even speak may contain coronavirus. If another person is standing close by, these tiny droplets may be breathed in or land in the eyes and cause infection with coronavirus. The closer people are to each other, the greater the risk of infection. Smaller droplets may float in the air, but larger droplets quickly settle onto nearby surfaces such as tabletops and chairs. It is the larger droplets that are responsible for most coronavirus spread. The importance of airborne spread indoors by the smaller droplets is uncertain.
- Spread by direct contact: If you shake hands with someone who has coronavirus infection and has coughed into their hand you may transfer coronavirus onto your own hand. If you then touch your nose, mouth, or eyes you can also become infected. Shaking hands, hugging, or kissing someone who is infected may also pass on the coronavirus.
- Spread by indirect contact: If a person coughs or sneezes into their hand and then touches a surface such as a tap, door handle or phone, coronavirus may be transferred to that surface. If someone else touches that surface and then touches their face coronavirus can be transferred and infect them. Coronavirus may survive on a solid surface for 24 hours or longer if not removed by cleaning or disinfection. Therefore, people may not even see the person who infects them.
- Coronavirus is not spread by mosquitoes, flies, insects, rats, or pets.
1-6 Can people who look well also spread coronavirus?
Yes. Anyone who is infected with coronavirus can pass it on to others just before they become ill and while they are ill with COVID-19. Spread can also occur from infected people who appear well and have no symptoms of COVID-19 (are asymptomatic). Therefore, all people with coronavirus infection can infect others whether they have symptoms or not. Some people with coronavirus may remain infectious for a few days after they feel better again.
1-7 What is the incubation period of COVID-19?
The incubation period of COVID-19 is the time between being infected with coronavirus and the time of first feeling unwell. It is usually about 5 days but it can be anywhere between 2 to 14 days.
1-8 How many people does one person usually infect with coronavirus?
If no protective measures are taken, one infected person will spread coronavirus to an average of three other people. This means coronavirus is three times more infectious than the influenza (flu) virus. However, coronavirus is far less infectious than some other viral diseases, such as measles.
1-9 How many people infected with coronavirus become ill?
It appears that many people who get COVID-19 remain well and do not develop any symptoms of the disease (30% to 50% of people are asymptomatic). This is a huge problem as they do not know that they are infected with coronavirus and are ‘silent spreaders’ of the infection.
1-10 How many people with COVID-19 will become seriously ill?
About 80% of people who are ill with COVID-19 will have a mild, self-limiting illness lasting 5 to 10 days. A further 15% will be moderately ill and need admission to hospital for oxygen and other supportive therapy. A further 5% will become seriously ill and need intensive care, usually requiring assisted ventilation. Therefore 20% of people with COVID-19 will need to go to hospital.
1-11 Do children get COVID-19?
Children and teenagers also get infected with coronavirus but most do not become ill. However a small percentage do become seriously ill and may even die of COVID-19. Therefore children and young people are thought to be an important source of infection to older people. Children who appear well may spread coronavirus to their parents and grandparents.
1-12 What happens if pregnant women get COVID-19?
Pregnant women can become sick with COVID-19 but coronavirus usually does not spread to their unborn baby in the womb and coronavirus is not present in their breast milk. Infection can however spread to the baby after birth from the mother’s respiratory droplets or by direct contact. Therefore, mothers must wear a mask and wash their hands carefully before breastfeeding their baby, for at least 14 days after the start of their symptoms.
The risk of COVID-19
1-13 Who is at risk of becoming seriously ill with COVID-19?
People at increased risk for serious illness are:
- Older people, especially those over 70 years of age. The older they are the greater the risk as the immune system weakens in the elderly.
- People with chronic lung conditions such as emphysema or tuberculosis.
- People with other medical conditions (co-morbidities) such as heart disease, cancer, high blood pressure and diabetes.
- People with untreated HIV infection and those who do not adhere to antiretroviral treatment (ART). People living with HIV who take their ART correctly and have an undetectable viral load may not be at increased risk.
- Health workers and support staff who care for many infected patients and are exposed to a lot of coronavirus.
- Men are at higher risk of severe COVID-19 than women. It is not known why.
1-14 How many deaths will COVID-19 cause?
The number of people in a country who die of COVID-19 depends on several things, including the average age of the population, the availability and quality of health care, and how many people have chronic diseases. Information from developed countries suggests about 3% of people who are ill with COVID-19 will die even with hospital treatment. In poor communities with a weak health service, 5% or more may die.
Many people with coronavirus infection remain well (they are asymptomatic) and more than 97% will recover. Many people with coronavirus infection are therefore not tested and not included in the official totals. Therefore, the mortality rate for all people infected with coronavirus (symptomatic plus asymptomatic) is expected to be less than 3%.
1-15 Can people infected with coronavirus avoid getting ill with COVID-19?
Most people with a healthy immune system will not get very ill with COVID-19. Therefore, it is important for everyone to try to live a healthy life. Even those who are infected with coronavirus must try to reduce stress, get enough rest, drink enough water and, if possible, eat small healthy meals. Smoking and drinking alcohol affects immunity and may increase the risk of getting severe COVID-19.
1-16 Can antibiotics be used to treat COVID-19?
No, antibiotics cannot be used to treat COVID-19, as antibiotics do not kill viruses.
1-17 Can COVID-19 be cured?
At the moment there is no medication proven to kill the coronavirus and cure COVID-19. However, many clinical drug trials show great promise and are being evaluated as potential treatments.
Case study 1
Ivy is a nurse at a local clinic. She is well but worried that she may have coronavirus infection. Two weeks ago, she sang at a choir practice with someone who now has COVID-19. After the meeting she shook his hand. She is not sure whether coronavirus is the same as COVID-19.
1. What is the difference between coronavirus and COVID-19?
Coronavirus is the cause of an illness called COVID-19.
2. Can she have coronavirus infection but not be sick with COVID-19?
Yes, as many people with coronavirus infection remain well.
3. Could she have become infected at the choir practice?
Yes, as coronavirus is spread by droplet spread. Even if an infected person is well they can still spread the virus.
4. Could she have become infected by shaking his hand?
Coronavirus can also be spread by direct contact. If he had coughed into his hand and she touched her face after shaking hands, coronavirus could have been transferred from his hand to her face.
Case study 2
A week before, a schoolgirl aged 10 years attends a friend’s birthday party where one of the parents is later diagnosed with COVID-19. Her elderly grandfather, who has diabetes, lives with the family. Her mother is worried that the whole family may get infected.
1. Is the schoolgirl likely to become ill with COVID-19?
Yes, she is likely to become infected but may not develop symptoms or may only have mild symptoms of COVID-19.
2. Should she be worried about her grandfather?
Yes, as he is elderly and has diabetes. Both are risk factors for severe COVID-19.
3. When would you expect him to become ill?
As the average incubation period for COVID-19 is 5 days she could become infectious 5 days after the party. It would then take another 5 days before her grandfather became ill. So she could expect him to become ill in the next few days. However the incubation period could be between 2 and 14 days.
4. How many people are usually infected by someone with coronavirus infection?
About three. Each of them will probably infect another three people, who in turn will infect three more people. In a short while, at least thirteen people will be infected. With another round of infections, there will be an additional 27 infected people. This shows how quickly COVID-19 can spread in a community.