We need your help now

Support from readers like you keeps The Journal open.

You are visiting us because we have something you value. Independent, unbiased news that tells the truth. Advertising revenue goes some way to support our mission, but this year it has not been enough.

If you've seen value in our reporting, please contribute what you can, so we can continue to produce accurate and meaningful journalism. For everyone who needs it.

Michael Cooper/PA Wire
what's what

Who are the WHO? What does 'community transmission' mean? - A Covid-19 glossary of terms

We’re hearing lots about pandemics, contact tracing and community transmission. Let’s break it all down.

THE NUMBER OF Covid-19 cases confirmed worldwide is now nearing 100,000 as the death toll also rises from the virus.

Authorities here have told citizens to be on high alert and take precautionary measures if they have been to some of the areas most affected by coronavirus or if they’ve been in close contact with a confirmed case.

In the past few weeks, we’ve been hearing an awful lot about this relatively new virus and what actions we should take to try limiting its spread.

Here’s a breakdown of some of the commonly used terms related to Covid-19, and what they’re all about.


There’s a reason we knew it first as coronavirus, before we knew it as Covid-19.

Coronaviruses are a large family of viruses that can cause illnesses in humans and animals. In humans, many of them cause respiratory infections ranging from the common cold to more severe conditions such as Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Symptoms (SARS).

Covid-19 is the most recently discovered coronavirus.


As mentioned above, Covid-19 is an infectious disease and the most recently discovered form of coronavirus. It was unknown before the outbreak in Wuhan in China in December 2019.

Its symptoms include fever, tiredness and dry cough. Some people become infected but don’t develop any symptoms and don’t feel unwell. 

In more severe cases, it can lead to serious illness with older people and those with underlying medical conditions most at risk.


This is the actual name for the virus which causes the disease, which is Covid-19.

Viruses and the diseases they cause often have different names, such as HIV (the virus) and AIDS (the disease). 

Viruses are named based on their genetic structure, and are officially named by the International Committee on the Taxonomy of Viruses (ICTV).

On 11 February, ICTV officially the announced the name of the virus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This was chosen because the virus is genetically related – although still different – to the coronavirus responsible for the SARS outbreak of 2003.

The World Health Organisation says it always refers to it as Covid-19 because the name SARS can have “unintended consequences in terms of creating unnecessary fear for some populations, especially in Asia which was worst affected by the SARS outbreak in 2003″.

Community transmission

Community transmission means infections within a population are not imported from another virus-hit area.

Put simply, for example, community transition in Ireland would mean a person who gets Covid-19 despite having not been to the affected outbreak areas, e.g. northern Italy, China, Japan, South Korea.

The first case of community transmission in Ireland was confirmed by the Department of Health last night. 

Dr Tony Holohan, the chief medical officer at the Department of Health, said the case cannot yet be explained. / YouTube

Contact tracing

This is when attempts are made to trace all the people who a confirmed case may have been in close contact with. 

Health authorities here have always been keen to emphasise that contact tracing is an essential “process” that it undertakes each time there’s a confirmed case.

According to the ECDC, a contact of a Covid-19 case is a person not presenting symptoms, who has or may been in contact with that case. 

That could be family members, classmates, work colleagues or even someone they were on public transport with.

Based on a risk assessment, authorities will aim to make contact with all of these people and take whatever appropriate action – testing, self-isolation etc – is needed.

The main focus of contact tracing, however, is on the close contacts a confirmed case has had. This could be any individual who has had greater than 15 minutes face-to-face (2 metres or less) contact with a confirmed case, in any setting. It could also be someone you sat within two seats of on a plane, or someone you live with. 

Close contacts are most at risk of contracting the virus.


According to Ireland’s Health Protection Surveillance Centre, an outbreak of infection “may be defined as two or more linked cases of the same illness or the situation where the observed number of cases exceeds the expected number, or a single case of disease caused by a significant pathogen.

Outbreaks may be confined to some of the members of one family or may be more widespread and involve cases either locally, nationally or internationally.

The reason why Covid-19 is being referred to along with the term is outbreak is exactly that. It is a widespread illness where the observed number of cases continues to rise and rise.

The WHO says: “Disease outbreaks are usually caused by an infection, transmitted through person-to-person contact, animal-to-person contact, or from the environment or other media.

Occasionally the cause of an outbreak is unknown, even after thorough investigation.

Mortality rate

The CDC in the US defines mortality rate as the measure of the frequency of occurrence of death in a defined population.

Usually you’ll hear the number of deaths from coronavirus expressed as a percentage of the overall number of cases, or the number of people who die in every 1,000 cases.

On Tuesday night, the head of the World Health Organisation said that the global mortality rate was 3.4%. This figure primarily reflects the number of cases and deaths in China, which has been worst hit by far.

Other countries have different mortality rates with Italy’s, for example, hovering around 3%. 

Mortality rates vary by country depending on factors such as how effective screening is and how effective containment measures have been.


The World Health Organisation is leading the battle against the virus and gives daily updates on the Covid-19 crisis.

It’s a specialised agency of the United Nations with the primary role of directing international health within member states. Its World Health Assembly is attended by representatives from all member states, with an executive board of 34 technically-qualified members elected for three-terms.

Its role is to support countries as they coordinate efforts of governments and partners on health-related matters.

In the case of coronavirus, it has a wealth of information and guidance from situation reports to travel advice. You can find it all here


The European Centre for Disease Prevention and Control is an independent agency within the European Union that occupies a similar role to that of the WHO, but in a European context.

It too has a multitude of information about Covid-19 on its site, and is constantly providing updates and advice to member states as the disease sweeps across Europe.

Within an Irish context, authorities here work with the ECDC and follow its advice and alerts closely when it comes to the current outbreak.

Self-isolation / YouTube

People who have been in close contact with a case, or are developing symptoms of Covid-19, are being told to self isolate for 14 days.

They’re told to follow the advice for the whole period, even if they don’t develop symptoms.

Among people self-isolating is Channel 4 News Anchor Jon Snow.

While following the advice, he says he’s finding it quite boring. 

Advice when self-isolating includes staying at home, separating yourself from other people, staying in a well-ventilated room, asking friends or family to carry out errands like groceries and telling delivery drivers to leave items outside for collection if you order online.

Pandemic / YouTube

The World Health Organisation has so far said that Covid-19 has not reached the level of a pandemic.

It defines a pandemic as the worldwide spread of a new disease. 

“An influenza pandemic occurs when a new influenza virus emerges and spreads around the world, and most people do not have immunity,” it says.

Viruses that have caused past pandemics typically originated from animal influenza viruses.

However, despite Covid-19 now being reported in more than 75 countries right around the world, the WHO has not called this a pandemic yet. If the number of cases continue to rise, it’s likely only a matter of time. 

The word is used interchangeably with epidemic, but epidemic would refer more in this context to a disease focused within a community.

The word epidemic is being used to describe the outbreak of Covid-19 in China, for example.

National Public Health Emergency Team

This is the team made up of officials, including those from the Department of Health and HSE, and they have met constantly to discuss the latest updates as Covid-19 has spread.

It issues regular advice on the risk to the population, and says whether cases have been confirmed in Ireland.

Familiar faces at this stage will be chief medical officer Dr Tony Holohan, deputy chief medical officer Dr Ronan Glynn, and Dr John Cuddihy who is the director of the Health Protection Surveillance Centre – a subsection of the HSE.

They give daily briefings to the press, providing the latest health advice to the general public.

Readers like you are keeping these stories free for everyone...
Our Explainer articles bring context and explanations in plain language to help make sense of complex issues. We're asking readers like you to support us so we can continue to provide helpful context to everyone, regardless of their ability to pay.

Your Voice
Readers Comments
This is YOUR comments community. Stay civil, stay constructive, stay on topic. Please familiarise yourself with our comments policy here before taking part.
Leave a Comment
    Submit a report
    Please help us understand how this comment violates our community guidelines.
    Thank you for the feedback
    Your feedback has been sent to our team for review.

    Leave a commentcancel