|Anosmia||Loss of your sense of smell. There are many reasons why this can happen including injury to the nerve that helps you smell, injury to the nose or sinuses, or a viral infection of the respiratory system. Anosmia is a reported symptom of COVID-19.|
|Antibodies ||Antibodies are:|
- small proteins that are produced by the immune system
- also called immunoglobulins
- produced by white blood (or plasma) cells.
Antibodies help defend the body against infectious organisms such as bacteria (eg, Escherichia coli, Staphylococcus aureus) and viruses (eg, influenza A virus, hepatitis C virus) that can cause disease.
There are different types of antibodies, some are produced soon after exposure to an antigen, while others appear after a longer period of time.
So far there is not enough information to draw any conclusions about immunity to COVID-19, even if the presence of antibodies specific to the SARS-CoV-2 virus (the virus that causes COVID-19) are detected in a blood sample.
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To understand antibodies, it’s important to understand antigens. Antigens are substances that can trigger an immune response. They are usually an organism or particle that is foreign to the body, such as a bacteria, a virus or pollen. Blood or a transplant organ from another person can also act as an antigen.
If you have a normal immune response, your body will recognise a threatening antigen, like those attached to viruses, and will defend your body against it. A crucial part of this defence system is the production of antibodies, they tightly bind with a unique antigen, and either neutralise it or tag it for destruction.
The body makes thousands of antibodies and each one is assigned to a specific antigen. After the first encounter with an antigen, your body may take some time to produce the required antibody. But in the future, the memory cells of your immune system can recognise an antigen and swiftly produce antibodies in response. This is called ‘active’ or ‘acquired’ immunity, and it can occur after a disease or a vaccine. Some people produce antibodies to substances that aren’t usually harmful, such as peanuts – this process is commonly known as an allergic response.
If a person has an autoimmune disease, they produce antibodies that stick to their body’s own proteins and damage healthy cells.
People who are immunodeficient cannot produce an appropriate immune response, which makes them prone to more serious bouts of illness.
Related: antibody tests, immunity, plasma, vaccines
|Antibody tests |
Blood tests that look for specific antibodies. Sometimes, they are called serology tests. Having the antibodies can be a sign you have been infected by (or immunised against) the disease caused by a particular antigen.
Tests that detect the presence of antibodies to the antigens that cause certain diseases, such as measles, can sometimes determine if a person is immune to that disease.
There are different types of antibody tests. Some are sensitive to the antibodies that your body produces immediately after an infection, while other antibody tests will detect antibodies that appear later. Antibody tests are not recommended for diagnosing an active (acute) infection, because antibodies to an antigen take time to develop. You may be infectious even if your serology or antibody test results are ‘negative’.
Currently, a ‘reliable’ antibody test may show that someone has recovered, or is recovering, from COVID-19.
However not enough is known about COVID-19 for the presence of antibodies specific to SARS-CoV-2 to lead to any conclusions about immunity. In Australia, antibody tests for COVID-19 or any other disease cannot legally be advertised because their results are complicated and need to be interpreted by a health professional.
During an epidemic or pandemic like COVID-19, antibody tests show how many people in the population have or may have been infected with a disease.
Related: antibodies, immunity, plasma, serology, vaccines
|Bacteria ||Microscopic, single-celled organisms that can cause human diseases. Bacteria can be killed or damaged by antibiotics.|
Bacteria are larger than viruses. Not all bacteria in our bodies cause disease. For example some bacteria in your digestive system can protect you from gut (intestinal) infections caused by other bacteria.
If a bacteria causes an infection, the infection tends to be in one area of the body (eg, tuberculosis is an infection in the lungs). Unlike a virus, a bacterium is a living organism and can reproduce without invading a host cell.
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Covid is a viral infection, not bacterial infection, so antibiotics cannot be used to treat the virus. They may play a role if there is a secondary bacterial infection e.g. pneumonia.
Inappropriate and excessive use of antibiotics over the past few decades has lead to an increase in the number of bacteria now resistant to different antibiotics. These bacteria are sometimes described as ‘superbugs’ and can be very hard to treat.
Related: coronavirus, virus
|Cardiovascular system ||A group of organs that includes the heart (cardio) and blood vessels (vascular). The cardiovascular system is responsible for pumping and circulating blood around the body.|
Cardiovascular diseases include diseases affecting the heart, such as heart failure and coronary artery disease, and disease affecting the blood vessels like a stroke.
Even though it’s a respiratory (lungs and airways) disease, COVID-19 can cause cardiovascular complications, especially for those with pre-existing heart conditions or uncontrolled, high blood pressure.
Related: respiratory system, comorbidity
|Cohort study ||Research that involves observing a group of people (cohort) over a period of time to investigate the cause of a disease and to make connections between risk factors and health outcomes.|
This type of study is observational, which means that researchers are watching a group of people behave the way they normally would - there is no ‘experiment’ taking place.
Typically, these researchers follow a group of people to learn more about a condition or to understand how certain risk factors might negatively impact on a person’s health in the long term.
During the COVID-19 pandemic, cohort studies have helped researchers learn about how the virus affects people, what health conditions are risk factors for severe illness and what actions help prevent the spread of the virus.
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Retrospective cohort studies use studies or information that already exists. They try to identify risk factors that might increase someone's chance of developing a specific health condition. For example, one retrospective-cohort study called 'Dying to be famous' looked at biographical data belonging to deceased rock and pop stars who reached fame between the years of 1956 and 2006, to see if negative childhood experiences predisposed them to risk-taking behaviour.
Prospective cohort studies look towards the future. Researchers may have a theory about what might cause a disease. To test this theory they observe a group of people – a cohort – over a period of time and see if there are any changes in health outcomes linked to possible risk factors they have identified.
The Framingham Farm Study is an example of a prospective cohort study, where 5209 men and women were recruited in 1948 and followed for decades to see if anything they did influenced their cardiovascular health. The study made several discoveries about the effects of smoking, cholesterol level and high blood pressure on heart health.
Related: epidemiologist, incidence, prevalence, randomised control trial
When a person has more than one health condition at the same time. For example someone who is diagnosed with COVID-19 might already have been living with multiple health conditions like asthma or high-blood pressure (hypertension). These conditions are comorbidities. They are sometimes called ‘existing’, ‘pre-existing’ or ‘underlying’ conditions’.
Comorbid conditions can make a person more vulnerable to illness from other causes. During this COVID-19 pandemic, researchers have been paying attention to comorbidities to see if they can help protect people who are at higher risk of worse health outcomes.
Related: cardiovascular system, morbidity, respiratory system
|Conjunctivitis ||A condition where the membrane (called the conjunctiva) that lines the inside surface of the eyelids and the front of the eyeball is inflamed. Conjunctivitis |
Note: ‘-itis’ at the end of a word usually signposts a disease characterised by inflammation. For example, appendicitis is a condition caused by the inflammation of the appendix. There are other ‘ itis’ examples in this document)
- can be caused by infection (virus, or bacteria) or as part of an allergic reaction.
- is also known as ‘pink eye’ and is contagious if caused by a bacteria or virus.
- is a reported symptom of COVID-19.
|Contact tracing |
A method to find people who have been exposed to a person with a confirmed case of an infectious disease, like COVID-19.
Close contacts of someone who has been exposed to COVID-19 are at risk of being infected and infecting others, even if they don’t display any symptoms. Once close contacts are identified, they are asked to self-isolate for a 14-day period.
Contact tracing has been around since before COVID. For example, it has been used to help identify people who may be at risk of Hepatitis C or HIV infection.
Related: quarantine, self-isolation
A large group of viruses that cause diseases in humans and animals. In humans coronaviruses can cause mild diseases like the common cold as well as more severe diseases such as COVID-19.
The coronavirus that causes COVID-19 is called SARS-CoV-2. Other illnesses caused by coronaviruses include Middle East Respiratory Syndrome (MERS) caused by the MERS coronavirus (MERS-CoV) and Severe Acute Respiratory Syndrome caused by the SARS coronavirus (SARS-CoV).
Corona means crown or wreath in Latin – under a microscope the coronavirus has bulbous spikes, like the pointy end of a crown.
Related: bacteria, COVID-19, pandemic, SARS-CoV-2
A new, infectious disease caused by the coronavirus SARS-CoV-2.
Viruses often have different names from the diseases that they cause, for example HIV is the virus that causes AIDS.
There have been a lot of words used to described COVID-19.
Before 11 February 2020, when the World Health Organisation (WHO) gave COVID-19 its name, the disease was often referred to as coronavirus in the media. However, there are many coronaviruses in the world, and only one type that leads to the disease COVID-19.
The name COVID-19 is derived from Coronavirus disease 2019.
Related: coronavirus, epidemic, pandemic, SARS-CoV-2, WHO
A medical treatment that restores a sick person to health. If a person is cured, it means that they no longer have the condition that caused their illness. A cure is different from prevention, and from symptom management.
For example,. tuberculosis can be cured by taking certain medicines while measles can be prevented with a vaccine. Generally, chronic conditions cannot be cured but their symptoms can be treated. Diabetes, for example, can be managed with medicines such as insulin injections.
There is currently no cure for COVID-19.
Related: treatment, vaccine
Changes to, or loss of, the sense of taste. There are a number of reasons why this can happen including as a side effect of certain medicines (eg, chemotherapy), and as a result of viral infection.
This can be a symptom of COVID-19.
An illness, or other health-related event, that affects a large number of people in a community, population or region, and is occurring at a higher rate than expected. An epidemic can refer to diseases that are treatable, like typhoid, or not treatable like COVID-19.
Epidemics can also refer to health-related behaviours.
A pandemic is declared when the infectious disease outbreak occurs on a global level.
Related: contact tracing, COVID-19, epidemiologist, pandemic
Public health professionals and researchers who investigate patterns, causes and prevention of disease and injury in people. During an outbreak, like COVID-19, they study the affected population to identify the agent responsible, the people who are at risk, determine how to stop the spread of the disease, and use their gathered data to create strategies to prevent a similar outbreak from happening again.
Related: cohort study, contact tracing, incidence, prevalence, randomised control trial, WHO