COVID-19. COVAX. Clinical trial. Many new words and phrases have entered everyday language over the past year. But what do they all mean?

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Access to COVID-19 Tools (ACT) Accelerator is a collaborative effort between the WHO and partners, working to deliver the most efficient and effective tools to fight a disease. Their work is organised into four pillars: diagnostics, treatment, vaccines and health system strengthening. They are currently working to ensure equal access to the COVID-19 vaccine with the COVAX Facility. 


An added ingredient used in some vaccines to trigger a stronger immune response which enhances the vaccines effectiveness. 


Molecules that hang around pathogens which trigger an immune response from your body causing it to produce antibodies. 


The good guys. They defend your immune system and fight off harmful pathogens. 


Being asymptomatic means that you aren’t showing any signs of having a disease but you are still contagious with it and can spread it to others. There are records of asymptomatic COVID-19 cases. 


The Coalition for Epidemic Preparedness Innovations (CEPI) is a global partnership between public, private, philanthropic, and civil society organisations to develop vaccines to stop future epidemics. CEPI is focused on the COVAX vaccine research and development portfolio. 

Clinical trial  

A type of research which studies new medical treatments, tests, procedures, and equipment on volunteers and evaluates their effects on human health outcomes. The COVID-19 vaccination was developed using clinical trials. 

Close contact  

Being in close proximity/sharing a space with a probable or confirmed case.

Elisabeth, nurse and vaccinator, collects vaccines from a cold box, at a health centre in South Sudan. © UNICEF/UN0349001/Obel

Cold chain 

Vaccines need to be kept at just the right temperature to maintain their effectiveness. The chain of events which ensure a vaccine stays at the correct temperature from the moment its manufactured until vaccination. The cold chain allows health workers to deliver life-saving vaccines to every corner of the world.  

Community transmission 

The spread of a disease or illness in a location such as a suburb or a city.  


The ability of a disease to spread from one person to another (contagious or infectious).  

Contact tracing 

The steps taken to assess, identify and manage a person who has been exposed to a contagious disease in order to prevent further spread. 


A term which refers to a family of viruses that cause respiratory illnesses. COVID-19 is the latest in the coronavirus family. 


The only global initiative that ensures equal access to COVID-19 vaccines worldwide. UNICEF is leading the procurement and delivery of more than 2 billion vaccines to those who would otherwise go without, especially in lower-middle income countries. COVAX is co-led by CEPI, Gavi and WHO. 


The name doctors and scientists gave to the ‘coronavirus’ disease that started spreading around the world in December 2019. It stands for Coronavirus Disease 2019. 

Dagnoko Salimata, 39, health worker is one of the first people to recive a COVAX COVID-19 vaccine ij Côte d'Ivoire. © UNICEF/UN0423305/COVAX/Miléquêm Diarassouba


The constant presence and/or prevalence of a disease in a population within a geographic area. Common diseases are endemic around the world like chickenpox or the flu. 

Epidemic vs pandemic 

An epidemic is an increase, often sudden, in the number of cases of a disease above what is normally expected in that population in an area. The Ebola virus was epidemic to Africa and could have been pandemic if it were not contained.  

A pandemic is an epidemic that has spread over several countries or continents, usually affecting a large number of people. The COVID-19 pandemic is the latest example of that.   


Epidemiology is the medical branch that studies the distribution and determinants of health events like the COVID-19 pandemic. It applies these studies to help control these health events. People who study and practice epidemiology are called epidemiologists.  

Essential activities  

These are the activities that require us to leave our homes to maintain health and wellbeing even during a lockdown. They include seeing a doctor, exercising, buying essential items (food/medicine/toilet paper etc.), caring for a family member and many more. 

Essential worker  

The heroes of the pandemic who risk infection in order to deliver essential services. They include healthcare workers, supermarket workers, trade workers and more.  

Health worker Mekdes, 23, goes door to door in Ethiopia to vaccinate children against polio. © UNICEF Ethiopia/2020/Tadesse

Flattening the curve  

Taking protective measures such as social distancing, lockdown and practicing good hygiene to control the number of new cases of COVID-19. On a graph this looks like a hump being flattened out. 


This is an inanimate object that can hold the disease and potentially spread when a live host encounters it. It can be something as inconspicuous as a towel, a door handle or even on your dog’s hair. COVID-19 can be spread by fomite and that is why measures were taken to reduce contact with objects outside of your home. 

Gavi Vaccine Alliance 

Gavi is an international organisation that brings organisations from public, private and government sectors the world over. Their core partners include the WHO, UNICEF, the World Bank and the Bill and Melinda Gates Foundation. They have the shared goal of creating equal access to new and underused vaccines for children living in the world’s poorest countries. Gavi is focused on procurement and delivery for COVAX. 

Herd immunity 

Everybody looking out for each other. Herd immunity is the indirect protection from infectious diseases as a result of an immune population. This immunity is achieved through vaccination or immunity developed through previous infection. Herd immunity against COVID-19 will be achieved through vaccination, not through exposure to the pathogen that causes the disease.  


The process of both receiving a vaccine and becoming immune to a disease as a result.  


Someone whose immune system struggles to fight off diseases or infections as well as most people. There are several illnesses which can cause someone to become immunocompromised. Immunocompromised people are at a higher risk from COVID-19. 

Incubation period 

The time it takes from contracting a disease to showing symptoms. For COVID-19 it takes on average 5-6 days but can take up to 14.

Isolation/self isolation

Separating yourself from others when you are sick to prevent the spread of a disease.  


The frustrating but neccessary community quarantine measures take to contain the spread of a disease. Large scale physical distancing measures and movement restrictions known as a ‘lockdown’ can slow COVID-19 transmission by limiting contact between people.  
A child is vaccinated against measles at a UNICEF-supported Nutrition Health Centre in Somaliland. © UNICEF/UN0414894/Naftalin


A highly contagious and serious disease caused by a virus which causes fever, rashes, a cough, and without treatment, death. Worldwide measles deaths climbed 50 per cent from 2016 to 2019 due to low vaccination rates.  


The spreading of false or unconfirmed information. In a vaccine context, this can be the spread of conspiracy theories, personal opinions or scientific statements that have not been medically proved or confirmed. 


Measles, Mumps and Rubella. These viruses are endemic to most of the world. MMR is a combined vaccine which immunises against all three and has been effectively used in children to develop strong immune systems.  


A disease outbreak is an unexpected increase in the number of cases in a smaller area like a suburb or a town. 

Passive immunisation 

The transfer of antibodies from one person to another, providing temporary protection from diseases. Disappears within a few weeks or a month.  


The bad guys. These are the germs that cause disease. They come in the form of bacteria, a virus, fungus or parasite.  


Polio or poliomyelitis, is a disabling and life-threatening disease caused by the poliovirus that largely affects children under five. The infection would get into the spine and cause paralysis. Since 1988, the number of polio cases has decreased by 99 per cent, thanks to the Global Polio Eradication Initiative. UNICEF is part pf the Initiative along with other organisations and national governments helping to distribute the polio vaccine.


Personal Protective Equipment (PPE) is equipment used to help health workers and anyone directly involved with infectious diseases to prevent the spread of the illnesses. This includes masks, face shields, gloves and other coverings. In 2020, UNICEF delivered nearly half a billion items of PPE to front line health workers.
UNICEF Australia International Program Coordinator for Health (child survival and nutrition) Beth Stirling inspects PPE supplies at the warehouse in Sydney. Last year, UNICEF Australia shipped $140k worth of personal protective equipment (PPE) to Timor-Leste including gloves, masks, respirators and goggles. © UNICEF/UNI342196

Preventable diseases

Diseases that can be prevented through vaccination. Many life-threatening diseases have been contained in Australia because of vaccines such as diphtheria, measles, mumps, polio and more. 


Not the same as isolation and social distancing, quarantine is preventing healthy people who may have been exposed to contagious diseases from potentially spreading the disease.

R0 / reproductive rate  

This is the metric to determine the rate at which a disease spreads and estimating the average number of new cases at any given point by using complex mathematical models developed through data sets and assumptions. R0 estimates that COVID-19 is slightly more contagious than the seasonal flu but far less contagious as a disease like measles.  

R+D Blueprint 

The Research and Development (R+D) Blueprint is a global strategy and preparedness plan established by the WHO. It’s aim is to fast-track the availability of effective tests, vaccines and medicines that can be used to save lives and avert large scale crisis. It is being used to help develop and distribute the COVID-19 vaccine. 

Respiratory diseases  

These are illnesses caused by viruses that affect your airways and lungs. COVID-19 is a respiratory disease. Other respiratory diseases include bronchitis, diphtheria, whooping cough and the flu. The best way to prevent respiratory disease is with proper hygiene and getting the recommended vaccinations. Through UNICEF’s immunisation program, children around the world are receiving vital vaccines to common respiratory diseases.  


Severe Acute Respiratory Syndrome is a viral respiratory disease caused by a SARS-related coronavirus. It is an airborne virus and can spread through small droplets of saliva in a similar way to the cold and influenza. COVID-19 is the disease caused by the virus SARS-COV-2 (severe acute respiratory syndrome coronavirus 2). 


This is the process of determining whether a person may be contagious with COVID-19. It is a series of questions about the persons health and recent movements and a temperature check. Health care workers and other workers use screening to determine whether someone needs a coronavirus test.  

Social distancing 

The practice of maintaining space between yourself and other people to help control the spread of a disease. The required distance between people is 1.5m. 


Someone who shows the signs of a disease. The symptoms of COVID-19 include cough, shortness of breath and fever.

Therapeutic Goods Administration (TGA)

TGA is part of the Australian Government Department of Health and is responsible for regulating therapeutic goods including prescription medicines, vaccines, sunscreens, vitamins and minerals, medical devices, blood and blood products. TGA will be rigorously assessing each round of the COVID-19 vaccine for Australians. 
Children in Aden, Yemen proudly show off the spots on their arms where they were vaccinated during a mobile Measles and Rubella vaccination campaign supported by UNICEF. © UNICEF/UN0284429/Fadhel


The heroes. Vaccines are substances that prevent the spread of disease.  Vaccines reduce the risk of getting a disease by working with the good guys in your body’s immune system, antibodies, to build protection. Vaccines prevent highly contagious and even life-threatening diseases like the flu, chickenpox and polio. Now, vaccines are being used to combat COVID-19.


The act of introducing a vaccine to the body. They can be administered in a shot, by mouth or by a nose spray. 

Vaccine-derived outbreaks 

Vaccines contain dead or weakened versions of the disease they are trying to prevent – a vaccine-virus. After immunisation, the vaccine-virus will temporarily live within the vaccinated. During this time, the vaccine-virus will be excreted and in areas of low sanitisation, it will spread to other people and offer passive immunisation before dying out. In the worst case scenarios, it will infect an immunocompromised person and result in the disease spreading again. If all children in a community are immunised, the vaccine-virus has no one to infect and dies away. 


The medical apparatus used to assist patients with their breathing when they are suffering from lung related health problems. Ventilators are being used to treat those with COVID-19 because they cannot get enough oxygen themselves. Hospitals around the world have struggled because they cannot offer enough ventilators for the number of COVID-19 cases.   


Little bottles carrying big solutions. Vials are the tiny glass bottles you might see that hold the vaccine liquid inside.  


Viruses are small particles that can cause disease such as the flu, chicken pox and coronavirus. They're so small they can only be seen with microscopes. Viruses are spread through the air, on surfaces, or through food and water. That’s why proper handwashing is so important. Viruses are prevented with good hygiene and vaccinations. 


Vectors are living organisms that can transmit infectious pathogens between humans, or from animals to humans. They are transmitted by bloodsucking insects like mosquitoes or ticks which take the disease from one host and transfer it to another.  

Vector borne diseases  

Vector-borne diseases are human illnesses caused by parasites, viruses and bacteria that are transmitted by vectors. Malaria is a vector-borne disease, carried by mosquitoes.  

Viral shedding 

The time it takes for a virus to replicate in a host and become actively contagious. 

World Health Organisation (WHO)  

This is a UN organisation that coordinates and directs global health initiatives within the United Nations system. The WHO has been actively involved in the COVID-19 pandemic since the initial outbreak, collaborating with other health organisations to address the disease. 

Zoonotic Diseases 

A zoonosis is an infectious disease that has jumped from a non-human animal to humans. Zoonotic pathogens may be bacterial, viral or parasitic, or may involve unconventional agents and can spread to humans through direct contact or through food, water or the environment. It is believed that bats or pangolins spread COVID-19, meaning it is a zoonotic disease.