- Coronavirus outbreak was first reported in China’s Wuhan in December 2019
- Across the world, over 1.3 crore cases of Coronavirus have been recorded
- India is the third worst-hit nation by COVID-19
New Delhi: It was called the Novel Coronavirus given that it was a new virus about which nothing was known. Almost seven months since the outbreak was first reported in Wuhan, China, scientists across the globe are working round the clock to learn more about the virus. As they discover unknown aspects that can help put a check on the spread or help develop a cure, there are some terms that are being commonly used in the course of this pandemic. Here is a glossary of 15 such terms associated with the virus causing COVID-19 and its treatment.
When you spray deodorant or perfume and fine particles come out, that’s an aerosol. It can come out in different circumstances like in hospitals, when we put a tube inside a patient’s mouth to help in breathing explained Dr Rajesh Parikh, Director, Medical Research at Jaslok Hospital and the author of a book ‘The Coronavirus – What You Need To Know About The Global Pandemic’.
In epidemiology, aerosols or droplet nuclei refer to droplets less than or equal to 5 micron in diameter. Aerosols remain infectious when suspended in air over long distances and time.
According to WHO, Airborne transmission of SARS-CoV-2 can occur during medical procedures that generate aerosols. However, it is still evaluating whether SARS-CoV-2 may also spread through aerosols in indoor settings with poor ventilation.
Antibodies are proteins produced by a human body and used by the immune system to identify and neutralise foreign objects such as bacteria and viruses. Explaining the term in detail, Dr Mugdha Tapdiya, Senior Consultant, Internal Medicine at Fortis Hospital in Delhi’s Vasant Kunj said,
Antibodies are the immune response that our body develops against any infection. After contracting the COVID-19 infection, it takes one to three weeks for antibodies to develop. There are two kinds of antibodies – IgM (Immunoglobulin M) and IgG (Immunoglobulin G).
While IgM develops at an early phase of the infection, typically after the first week of contracting the virus, IgG antibodies are more likely to show up later – when an individual has recovered from the infection. IgM disappears after six weeks whereas IgG stays on for a longer period of time. However, as of now, it is not clear for how long IgG gives immunity against COVID-19.
IgM tells us that an individual has been exposed and he/she is either entering early immune phase or established immune phase, said Dr Ravindra Mehta, Chief of Pulmonary and Critical Care Medicine at Apollo Hospitals in Bengaluru.
When a virus enters a human body, it carries some characteristics on its surface and that’s called antigen. In simpler terms, antigen is particular attributes of the virus which helps our immune system and body in identifying the virus. Explaining the same with an example, Dr Ravindra Mehta, said,
Let’s say I’m COVID-19 and on my surface, I have a particular shirt, it’s a green shirt. This green shirt is like antigen. When an antigen test is done, it looks for the characteristics of the virus. Here, the test will lookout for a green shirt.
4. Fatality Rate
The fatality or mortality rate indicates the percentage of people dying because of the virus or disease. In epidemiology, a case fatality rate (CFR) is the percentage of deaths out of the total number of people who have been diagnosed with the disease. In the context of COVID-19, India’s fatality rate is 2.57 per cent (as on July 16) that is out of every 100 COVID-19 patients, two to three people are losing the battle against COVID-19. Globally, the fatality rate is 4.3 per cent.
Fomite is a technical term for contaminated objects and surfaces. Respiratory secretions or droplets expelled by infected individuals can contaminate surfaces and objects, creating fomites (contaminated surfaces).
Explaining how fomite transmission occurs, Dr Ravindra Mehta said,
Respiratory droplets expelled from our mouth can settle on surfaces and stay active for certain hours. Various studies have shown that COVID-19 survives for 12 hours to three days, depending on the surface. Let’s say I’m in a cafeteria, with my hands on the table. After a few minutes, I touch my nose and mouth. Here, I don’t know how many people visited the cafeteria before me, sat on the same table and whether or not the table was clean. But this way, the virus can reach my respiratory tract. Hence, the advice to not touch eyes, nose, and mouth and disinfect surfaces frequently.
From clothes, furniture, to doorknobs, any surface can be a fomite.
6. Inactivated Vaccines
Inactivated vaccines are made from microorganisms (viruses, bacteria, other) that have been killed through physical or chemical processes. These killed organisms cannot cause disease, states the WHO. Since inactivated vaccines do not contain live components, there is no risk involved. However, they may not induce an immune response after the first dose. Also, the response may not be long-lived. Inactivated polio vaccine was built using the same method.
7. Live Attenuated Vaccines
According to a document ‘types of vaccine and adverse reactions’ published by the WHO, live attenuated vaccines (LAV) are derived from disease – causing pathogens (virus or bacteria) that have been weakened under laboratory conditions. They will grow in a vaccinated individual, but because they are weak, they will cause no or very mild disease.
Using a weakened or inactivated form of the SARS-CoV-2 will help create a long-lasting immunity. Because the vaccine will be so similar to the natural infection that it helps prevents the virus by creating a strong and long-lasting immune response. Just 1 or 2 doses of most virus vaccines can give you a lifetime of protection against a germ and the disease it causes, said an expert from the Public Health Foundation of India.
In the past, numerous vaccines have been made using the LAV method. For example, BCG vaccine for Tuberculosis, oral polio vaccine, yellow fever, rotavirus, and others.
Live attenuated vaccines are less safe in comparison to inactivated vaccines for various reasons. One of them being, attenuated pathogens can revert to its original form and cause disease.
A change in the genetic structure of a virus which makes it either less harmful or more harmful is called mutation. Once a genetic structure changes, eventually the RNA will also change and hence, the activity of the virus will change. Explaining it in context of COVID-19, Dr Mahajan said,
SARS-CoV-2 may be a fast mutating virus this means its RNA structure or protein structure or genetic structure changes so fast that it may be different in one person and completely different in the tenth person that you detect. Mutation of the virus can affect the virulence of the virus that is how the virus presents a disease.
A change in the virus can lead to different characteristics. It can either be a minor mutation or major mutation where it either becomes weaker or way stronger. For example, influenza virus mutates every year.
It is a thought process that mutations are the reason some people get affected more, said Dr Mehta.
A pathogen or infectious agent is a biological agent (bacteria, virus or other microorganisms) that causes disease or illness to its host. For example, microorganism E. coli can cause diarrhoea.
Blood plasma, a yellowish liquid is a component of blood and consists of protein, minerals and antibodies. If someone has recovered from COVID-19 there are chances that the person’s body has developed antibodies that helped him/her to fight the virus. The same antibodies, if infused into a critical patient may provide passive immunity and help in the recovery process.
11. Positivity Rate
Positivity rate is the percentage of people who test positive for a particular virus or disease out of the total number of people tested. As of July 16, India’s positivity rate is 7.4 per cent which means out of every 100 individuals who are being tested, 7.4 are testing positive for Coronavirus. In comparison to this, according to John Hopkins University and Medicine, the United States has a positivity rate of 8.5 per cent.
12. R Number
R number refers to the effective reproduction number of COVID-19. In simpler terms, it denotes a disease’s capacity to spread. The R number signifies the average number of people that one infected person will pass the virus on to. For instance, if the R stands at 3, it means one COVID-19 infected person can transmit the virus to three people and those three can further spread the virus to three each. Ideally, R number should be less than 1.
The R number is of three types – R0 (pronounced as R naught), R (eff) and Rt. While R0 measures the average number of people who are infected by a COVID-19 person when no control measures are implemented, R (eff) measures the average number of people that would be infected by a single infectious person, taking into account the public health interventions implemented to contain the spread of the virus.
The effective reproduction number (R) can also be specified for a specific time and is then called Rt. The R0 is affected by biological, socio-behavioural and environmental factors and can fluctuate with a change in these factors, reads an excerpt from the book ‘The Coronavirus – What You Need To Know About The Global Pandemic’.
13. Recovery Rate
Recovery rate means the percentage of people recovering from the disease out of the total number of patients diagnosed. Currently, India has a recovery rate of 63.25 per cent which implies, out of every 100 COVID-19 patients, over 63 are recovering from the contagious disease. Globally, the recovery rate stands at 55.7 per cent.
Ribonucleic acid (RNA) is a nucleic acid present in all living cells. Like DNA is a building block for life, RNA is a building block of the virus. It produces a protein that determines the viral activity. All coronaviruses are RNA viruses so when the samples are tested to diagnose COVID-19, the team checks for viral RNA and human RNA. Explaining the testing procedure and detecting RNA, Dr Shelly Mahajan, Clinical Lead at CARINGdx, said,
The purpose of testing human RNA is to see whether a sample has been adequately collected or not. There are three genes of viral RNA and if any two genes are expressed in the sample or amplified in our test, we give it out as a positive sample.
15. RT-PCR Test
RT-PCR (Reverse transcription-polymerase chain reaction) is one of the COVID-19 diagnosis tests. For testing, a sample is collected using different methods like a swab is taken from a patient’s throat and nostril. RT-PCR test has a high specificity rate (identify those without the disease and not declare false positives). However, RT-PCR test takes a day to give results as the machine takes in 96 samples at a time so the testing laboratory has to wait for all the samples to be in before processing the results. Less than 96 samples can also be tested but that will increase the cost of the test.
16. Spillover Event
Transmission of a virus from one species to another is called a spillover event. The origin of the Novel Coronavirus or SARS-CoV-2 is unknown but it’s being said that the virus may have spilled over to humans from another intermediate host.
In the case of a human borne illness like COVID-19, super-spreader is an individual who is more likely to infect others, and spread the infection to a large number of people. Some patients are super-spreaders for two reasons – they have a virus which is slightly different and more virulent; they come in contact with a whole bunch of people without taking any precautions like wearing a face mask, sanitisation and social distancing.
The immune system consists of different kinds of cells including lymphocytes. These cells get activated when the human body is exposed to an attack such as COVID-19. T-cell is a type of lymphocyte and is a part of the immune response of the body in the fight against any infection or virus. T-cell is one of the soldiers and the essential cells of the body. The key point here, though it’s a part of the immune response, it’s different from antibodies.
Flow cytometry can calculate the absolute number of T cells in the blood even in case of COVID-19 but it is not being done as a routine though, said Dr Harsh Mahajan, Founder Of Mahajan Imaging and Chairman of CARINGdx.
19. Viral Load
The total amount of virus present inside an individual’s body is referred to as their viral load. RT-PCR (Reverse transcription polymerase chain reaction) which is considered as the gold standard test for the diagnosis of COVID-19 cannot detect the viral load. Current COVID-19 tests can only look for the presence of the virus.
There are two implications of the amount of the virus present in a human body; firstly, how badly it’ll impact the patient and secondly, how he/she will spread the virus, said Dr Ravindra Mehta
Zoonotic pertains to zoonosis, a term for any disease or infection that is naturally transmissible from vertebrate animals to humans. Zoonotic diseases are caused by harmful germs like viruses, bacterial, parasites, and fungi. These germs can cause many different types of illnesses in people and animals, ranging from mild to serious illness and even death, explains the US top medical body, Centers for Disease Control and Prevention.
NDTV – Dettol Banega Swasth India campaign is an extension of the five-year-old Banega Swachh India initiative helmed by Campaign Ambassador Amitabh Bachchan. It aims to spread awareness about critical health issues facing the country. In wake of the current COVID-19 pandemic, the need for WASH (Water, Sanitation and Hygiene) is reaffirmed as handwashing is one of the ways to prevent Coronavirus infection and other diseases. The campaign highlights the importance of nutrition and healthcare for women and children to prevent maternal and child mortality, fight malnutrition, stunting, wasting, anaemia and disease prevention through vaccines. Importance of programmes like Public Distribution System (PDS), Mid-day Meal Scheme, POSHAN Abhiyan and the role of Aganwadis and ASHA workers are also covered. Only a Swachh or clean India where toilets are used and open defecation free (ODF) status achieved as part of the Swachh Bharat Abhiyan launched by Prime Minister Narendra Modi in 2014, can eradicate diseases like diahorrea and become a Swasth or healthy India. The campaign will continue to cover issues like air pollution, waste management, plastic ban, manual scavenging and sanitation workers and menstrual hygiene.