The coronavirus: What is known so far
By Professor DYD Samarawickrama-April 23, 2020, 12:00 pm
Introduction
There has been a lot of articles published on the coronavirus in both the print and digital media. For anyone who missed those, there have been plenty of material presented on radio and television. However, there appears to be a few gaps. Therefore, this is an attempt to address those.
Predictions
Bill Gates, the founder of Microsoft predicted in 2015 that that the next great challenge facing humans would not be a nuclear war but an infection by a virus. Professor Devi Sridhar, Professor of Global Public Health at the University of Edinburgh, UK was more specific. In 2018, while addressing a literary festival in the UK, she said that a Chinese farmer would get infected by an animal and then spread it to the local community before getting on a plane and hitting the UK. No one expected her prediction to come true in two years.
The virus
Most know now why this virus is called coronavirus. But only a few are aware that coronavirus disease was first described in 1931, with the first coronavirus (HCoV-229E) isolated from humans in 1965. Other well-known coronaviruses are the virus causing Severe Acute Respiratory Syndrome SARS and that causing Middle East Respiratory Syndrome MERS.
The corona or the ‘crown’ consists of club-shaped glycoprotein spikes that project from the envelope surrounding the virus particle. These cause severe infections by first latching onto protein receptors sitting on the outside of lung cells enabling the virus to transmit its RNA material to human cells for multiplication.
The International Committee on Taxonomy of Viruses has designated the virus itself with the title of “SARS-CoV-2”. The official name for the disease caused by SARS-CoV-2 is called COVID-19 or Corona Virus Disease 2019. “We had to find a name that did not refer to a geographical location, an animal, an individual or group of people, and which is also pronounceable and related to the disease,” the WHO Director-General Tedros Adhanom Ghebreyesus said. All these terms are used interchangeably by many. However, one must remember that SARS-CoV-2 is the virus and COVID-19 the disease caused by the virus.
Reservoirs
These viruses have been in existence for a long time among wild animals. People are not the original source of coronavirus diseases. SARS, MERS and COVID-19 are zoonotic. That means that people originally catch the virus responsible from some animal.
Bats are often thought of as the source of coronaviruses. Snakes and other animals can be carriers. Yet even they seldom pass the virus directly on to humans. SARS probably first jumped from bats into raccoon dogs or palm civets. MERS went from bats to camels before infecting humans. Once in those animals, the virus seems to have mutated and acquired the capacity to infect humans who had come into contact with the animals at markets selling live animals. One theory is that there was direct contact with wild animals or their flesh or that meat from an infected animal was eaten raw or after partial cooking.
Transmission
The virus is highly infectious. Initially, it was thought that the transmission was via droplets. Therefore, the advice was to cover one’s mouth and nose with a tissue and bin it when coughing or sneezing and if you do not have a tissue, into the elbow of one’s arm. In addition, as the droplets can travel 2 metres or 6 feet, people were advised to remain apart by that amount: “social distancing”. However, recent research has shown that the virus can remain airborne for some time. in addition, research from Singapore has indicated that asymptomatic transmission, and transmission of SARS-CoV-2 in an environment with high temperature and humidity is possible. This is very concerning for Sri Lanka where the humidity is high.
Interestingly, the incidence of COVID-19 in Africa has appeared to lag behind the rest of the world with only 12,000 confirmed cases and 627 deaths as of Good Friday. This has been attributed to several factors such as limited testing, under-reporting, a low average age, high local temperatures and poor international air connections. Indeed, the affluent Africans who travel abroad frequently appear to be the first victims.
Stability on surfaces
Laboratory tests conducted in China has found that no infectious virus could be recovered from printed papers and tissue papers after a 3-hour incubation, whereas no infectious virus could be detected from treated wood and cloth on day 2. By contrast, SARS-CoV-2 was more stable on smooth surfaces. No infectious virus could be detected from treated smooth surfaces on day 4 (glass and banknote) or day 7 (stainless steel and plastic). It has been reported that the Chinese authorities have destroyed the bank notes in circulation in some areas and issued new bank notes. In other areas, notes and coins have been disinfected with ultra-violet light or high temperatures and quarantined for 14 days before re-circulation.
Sewage
Research conducted at Amsterdam airport early this year has shown the presence of the virus in human wastewater or sewage. “This could be explained by virus excretion from potentially symptomatic, asymptomatic, or pre-symptomatic individuals passing through the airport” the research workers stated. This raises the alarming possibility of faecal-oral transmission in areas with poor sanitation.
The sewage tests can act as an early warning system: Dutch scientists discovered that the virus was present in sewage from the city of Amersfoort before any cases were reported there. This is because the infected patients appear to excrete the virus well before they display symptoms. Equally, presence of the virus in sewage may also give an opportunity to monitor disease in cities and towns where there is a proper sewage system. Dutch scientists believe that the levels of the virus found in sewage can enable epidemiologists to determine how many people have been infected.
Pathology
After the SARS outbreak, the World Health Organisation reported that the disease typically attacked the lungs in three phases: 1. viral replication, 2. immune hyper-reactivity, and 3. pulmonary destruction.
In the early stages of an infection, the novel coronavirus rapidly invades human lung cells. It was noted that SARS virus loved to infect and kill cilia cells, which then sloughed off and filled patients’ airways with debris and fluids.
That is when phase two kicks in. Activated by the presence of the virus, the body steps up to fight the disease by flooding the lungs with immune cells to clear away the damage and repair the lung tissue.
When working properly, this defence mechanism is well regulated, confining itself only to infected areas. But sometimes one’s immune system goes haywire and kill not only the infected cells but also healthy tissue. So, one gets more damage instead of less from the “deranged” immune response.
During the third phase, lung damage continues to build—which can result in respiratory failure. Even if the patient survives, there is likely to be permanent lung damage. According to data available, SARS punched holes in the lungs, giving them “a honeycomb-like appearance” and these lesions have been reported to be present in the lungs affected by the current pandemic. Others have reported a ground glass appearance of both lungs. As more debris clogs up the lungs, the pneumonia worsens.
These holes are likely to be created by the immune system’s hyperactive response, which creates scars that both protect and stiffen the lungs. When that occurs, patients often have to be put on ventilators to assist their breathing. Meanwhile, inflammation also makes the membranes between the air sacs and blood vessels more permeable, which can fill the lungs with fluid and affect their ability to oxygenate blood. In other words, the lungs are flooded and breathing becomes very difficult. There is organ failure too. That is how people die.
Physiology
Clinicians and scientists are trying to understand at physiological level why this virus is so deadly. Heamoglobin in red blood cells carry oxygen around the body. Simply put, some believe that this virus binds to the heam group of haemoglobin impairing its function of carrying oxygen round the body. This then leads to a lack of oxygen in the tissues ending in organ failure. A clearer picture will emerge in due course.
Risk factors
A very recent paper published in China has reported the findings from 30 studies involving 53,000 patients. Predictors for disease severity included old age, male, smoking, and any comorbidity (especially chronic kidney disease, chronic obstructive pulmonary disease and cerebrovascular disease). Meanwhile, old age, followed by cardiovascular disease, hypertension and diabetes were found to be independent prognostic factors for COVID-19 related death.
Symptoms
Common symptoms include high temperature above 37.8 deg. C, cough, shortness of breath, body aches and muscle pain. Severe symptoms include very high temperature, pneumonia and kidney failure leading to death.
As the initial symptoms are similar to those of influenza, it is difficult to tell the difference between a mild case of coronavirus and the common cold. Doctors have to test for SARS-CoV-2 to be certain of the diagnosis. Symptoms of a common cold usually peak anywhere from two to three days after contracting it. On the other hand, the symptoms of COVID-19 tend to show up anywhere from 2 to 14 days after exposure.
The loss of taste or smell are two new symptoms which had been under-reported previously. In some cases, these were the only symptoms patients had experienced at the beginning. The loss of smell and taste has been followed by a general malaise and headache on the 3rd day. From around 5 – 7th day, high fever and a severe cough have appeared. There has also been a loss of appetite followed by a shortness of breath. The breathing rate has doubled to 30 per minute. Although the fever has decreased from about the 8th day, cough and the shortness of breath have continued plus severe muscle pain. From around the 10th day, fever has disappeared, but severe lethargy and shortness of breath have persisted. It seems to take about three weeks for these symptoms to disappear. In addition to these physical symptoms, patients have felt depressed and helpless. Some recover but tragically, others fail to do so.
Children
According to the US Centres for Disease Control CDC, children with COVID-19 might not display fever or cough as often as do adults. It adds that whereas most COVID-19 cases in children are not severe, serious COVID-19 illness resulting in hospitalization still occurs in this age group.
Whereas fever, cough, and shortness of breath were commonly reported among adult patients aged 18–64 years, these signs and symptoms are less frequently reported among paediatric patients. Among those with known information on each symptom, 56% of paediatric patients reported fever, 54% reported cough, and 13% reported shortness of breath, compared with 71%, 80%, and 43%, respectively, reporting these signs and symptoms among patients aged 18–64 years.
Mortality rate
Overall mortality rate for COVID-19 is about 2%. This compares well with SARS at 10% and MERS at 34%. Men are more likely to die due to this virus than women. In China, males accounted for 63% of the dead, 69% at present in Italy and more than 70% In the UK. Scientists think that this may be due to several reasons: basic differences in the immune system of males and females; males seeking treatment for their condition later than females; men washing their hands less; men more likely to smoke and drink alcohol than women. And men are more likely to have heart disease, diabetes and chronic lung disease.
Basic protective measures
There are several basic protective measures one can take:
1. Wash one’s hands frequently
The outer covering of this virus is fatty making it sticky. Washing one’s hands with soap and water for 20 seconds disrupts this outer covering making this action quite effective. It is important to recognise that normal hand washing lasts only about 5 seconds, so that effective hand washing for this virus should last four times as long.
Hand sanitizers also work but they must have at least 60% alcohol to be effective. Shoes and sandals can also harbour the virus. Therefore, leaving footwear outside or in the porch or a garage is safe practice.
2. Maintain social distancing
One must Maintain 2 metres (6 feet) between oneself and anyone who is coughing or sneezing. When someone coughs or sneezes, they spray small droplets from their nose or mouth which may contain virus. If you are too close, you can breathe in the droplets, including the COVID-19 virus if the person has the disease.
The impact of social distancing has been studied by scientists in the UK. Without this measure, one infected person can infect about 3 other persons in 5 days who in turn can infect about 400 persons in 30 days. With social distancing, one infected person can infect another one or two who in turn will infect only 15 persons in 30 days. However, it is important to realise that it takes about a month to see the effect of this on new infections in a population and another month to see a reduction in the number of deaths.
The much-quoted graph below shows the impact of social distancing and its duration on the pandemic. With case isolation alone, the peak is likely to be reached in about 3 months. If social distancing is in place, the peak will be lower, and the cases can be eliminated in about 8 moths. If social distancing is in place only for a short period, there is every likelihood of a resurgence in cases after 9 – 10 months. it is in place throughout the pandemic, the near complete reduction can be seen in 8 months. (See graph)
Simulations of transmission model of COVID-19:
A baseline simulation with case isolation only (red); with social distancing in place throughout the epidemic, flattening the curve (green), and a simulation with more effective social distancing in place for a limited period only, typically followed by a resurgent epidemic when social distancing is halted (blue). These are not quantitative predictions but robust qualitative illustrations for a range of model choices.
Source: Anderson, Heesterbeek, Klinkenberg & Hollingsworth, Imperial College, London March 2020
Available data from many countries tend to confirm this pattern of the spread of disease.
3. Avoid touching eyes, nose, mouth and other areas
Hands touch many surfaces and can pick up the virus. Contaminated hands can transfer the virus to one’s body. The virus can enter via all mucous membranes, including eyes, nose, mouth, gut and the areas down below (genito-anal regions). Therefore, one mut not touch any of these areas till hands have been washed thoroughly for 20 seconds.
4. Practise good respiratory hygiene
This means covering the mouth and nose with one’s bent elbow or tissue when coughing or sneezing. Dispose of the used tissue immediately. Wearing a mask will also help reduce the risk of the spread of droplets.
5. If one has fever, cough and difficulty breathing, seek medical care early
One must stay home if feeling unwell. If one has a fever, persistent cough and difficulty breathing, early medical attention must be sought. Hiding the disease is not going to help anyone. It may even kill the individual and spread the disease to others.
Wearing masks
The WHO is currently only advising those who are sick and showing symptoms of COVID-19 to wear a mask. Healthy persons only need to wear a mask if they are caring for someone with a suspected COVID-19 infection. The WHO emphasises that wearing a mask is only effective if it is combined with frequent hand washing with soap and water, and an alcohol-based hand rub. Professional-grade masks are best kept for healthcare workers who need them most. This advice may change with time. Some countries have already started instructing people to wear masks in public.
Testing
There are two types of tests available:
1. Antigen test: this will indicate whether a person has the disease. The tried and tested is the PCR (polymerase chain rection) Test. Two swabs are taken from the nose and the throat and the specimens subjected to the Test. It takes several days to get the results. There are reports of a rapid test being made available, but we await the outcome of clinical trials to be certain that these will diagnose the disease correctly and reliably.
2. Antibody Test: These detect whether a person had the disease. Several antibody tests have been assessed by the UK government scientists and found them not to be accurate nor reliable. Therefore, the UK government has not deployed this type of test so far. Several clinical trials are underway to develop an antibody test.
Treatment
There is no cure for COVID-19 at present. However, there are several clinical trials underway at present in Australia, China, the UK, the USA and about 8 other countries. Some trials involve the use of modified retroviral drugs used to treat HIV/AIDS. Another promising trial involves Remdesivir, which was tested previously in humans with Ebola.
Much has been written about the use of anti-malarial drugs such as chloroquine to treat COVID-19. However, there no evidence at present to justify their use. Several clinical trials are underway, but these are early days and one must not assume their effectiveness.
Very recently, US food and Drugs Administration FDA approved the use of convalescent plasma for treatment of COVID-19 patients. Convalescent plasma is plasma recovered from patients who have recovered from COVID-19. This is not a new method: it has been used in the past to treat diseases such as polio, measles, mumps and the 1918 flu epidemic. The reasoning is that plasma recovered from recovered patients may have antibodies to fight the infection.
However, this treatment will be limited to those suffering from serious or immediately life-threatening disease. Life threatening disease has been defined as respiratory failure, septic shock or organ failure. The reason for this limitation is that this treatment has not been effective in every disease treated in the past such as SARS and MERS.
Vaccine
The ultimate tool for the prevention of this disease is a vaccine. Although much research is underway, an effective vaccine is 12 to 18 months away. One promising development is in Oxford, UK where the research started soon after China published the gene sequence of the SARS-CoV-2 in January 2020. The Oxford team believes that their vaccine will be ready for testing by September. However, one must be cautious given that four decades after HIV/AIDS appeared, there is no vaccine yet. One factor favouring the Oxford team is that this virus seems to be stable when compared with the HIV which mutates at an astronomical rate.
Myths
There are a lot of “remedies” publicised in the social media. Unfortunately. Measures such as eating herbs, such as garlic, rinsing one’s nose, drinking hot water or alcohol and steam inhalation will not help. There is no scientific evidence to support the effectiveness of any of these measures.
Summary
This article provides current information regarding this deadly disease. It is hoped that a minority of people who are not following guidelines will realise the seriousness of this disease and start following instructions given by the government based on scientific and medical advice. “Stay at home, prevent spread and save lives” is a slogan well worth listening to if we want to beat this virus.
Declaration: This paper has been prepared in the public interest and in good faith.
SRI LANKA 