The pandemic has introduced a whole new set of words into our everyday language, some of which are terms rarely previously used anywhere outside academic and medical settings, let alone in headlines and conversations.

But as familiar as this new pandemic vocabulary has become, there are still several terms that often get mixed up both in the media discourse and ordinary conversations.

Here we try to find clarity over the terms that are most often misused.

Positivity rate and Prevalence

The positivity rate – also called 'percent positive' or 'test positivity rate' – is the percentage of people who test positive for COVID-19 out of all testing conducted in a country or a specific area. 

It's testing that determines whether an individual decides to self-isolate or not, and the number of total positive cases is what governments use to determine whether to impose stricter restrictions or ease them up.

But the positivity rate is not necessarily a straightforward measure of the virus's spread: for example, a 20 percent positivity rate doesn't mean that 20 percent of the population has COVID-19, it means that 20 percent of all people who got tested have the virus.

A high positivity rate might mean that the risk of infection is really high in a certain area, or it might mean that not enough testing has been done.

Generally, the higher the positivity rate, the higher is the risk of infection. When the positivity rate is high, countries normally try to lower it by imposing restrictions such as the mandatory use of masks in public, avoiding large gathering, and lockdowns. 

The World Health Organization (WHO) recommended in May 2020 that the positivity rate be kept below 5 percent for at least two weeks before governments consider easing restrictions. 

As not everyone who has COVID-19 gets tested, for example those who are asymptomatic and might not imagine having been infected, the number of actual cases within the population is likely to be higher than the one represented by the positivity rate. 

The number of people who are positive to COVID-19 out of the entire population is called prevalence – a number that experts can only roughly estimate, based on other factors including COVID-19 deaths and recovered patients.

Vaccine Efficacy and Effectiveness

Last year, the race to find a vaccine to COVID-19 produced various different vaccines which, after finishing clinical trials, were approved for use in several countries.

The COVID-19 vaccine was produced at an incredible speed, breaking record times for vaccine developments. The results of the trials were much better than expected, judging by their efficacy levels: the Pfizer-BioNTech vaccine recorded 95 percent efficacy in reducing infection, the Moderna vaccine 94.1 percent, and Oxford-AstraZeneca 90 percent.

Though efficacy and effectiveness are often used interchangeably to talk about how successful a vaccine is, efficacy refers strictly to how well a vaccine does during clinical trials, while effectiveness indicates the ability of the vaccine to prevent the disease in the real world.

Efficacy and effectiveness of a vaccine may differ, as a vaccine may perform differently in a larger setting, given to a broader population including people suffering from other health conditions.

Hospital Capacity and ICU/Hospitalization rates

In spring 2020, when Italy was one of the first countries in Europe to be hit dramatically by the pandemic, the country's health system was close to collapse, faced with huge numbers of people needing hospitalization.

In Italy's case, hospitals in the country had reached maximum capacity. Hospital or ICU capacity refers to the ability of hospitals to care for patients, including not only the number of beds available but also the number of staff present to take care of patients.

READ MORE Mar 20, 2020: How COVID-19 is pushing the Italian healthcare system to the brink of collapse

As a specific and countable number, capacity is calculated as the percentage of numbers of beds occupied divided by the total number of beds available in a hospital or ICU unit.

The ICU or hospitalization rate, instead, serves to indicate the number of patients who seek treatment in hospital after being diagnosed with COVID-19 over the total population of a specific area or country. 

Dropping hospitalization rates isn't necessarily good news: if cases aren't decreasing at the same time, a plunge in hospitalization rates might mean that patients who need hospital care aren't able to find a bed available. As hospitals fill up, their ability to take in new patients who might need treatment plunges.

Community spread and Transmission

Community spread, or community transmission, refers to how the virus moves within a population where a specific source cannot be identified, and people don't know exactly where and when they got infected as they didn't get in contact with a sick person.

An increase in community spread means that there's much more of the virus circulating within the community, and gatherings are risky.

Transmission is used to explain how the virus spreads from person to person, through contact or droplets. In this case, it is possible to trace back the transmission chain at the origin of the infection. 

These conditions are often present in a cluster – small outbreaks of COVID-19 specific to a certain time and place.

CLICK: REMEMBER THESE? OUR TOP STORIES OF 2020

Isolation and Quarantine

These are maybe the easiest definitions, but two that easily get confused. 

Isolation only refers to those who, after testing positive to COVID-19, have to keep away from other people so as to not infect them, including members of the same household.

Should the other member of the household also test positive, they should also isolate. If not, they would have to stay quarantined.

Quarantine is used to refer to those people who are not tested positive to COVID-19 but have been in contact with a recognized case; amid the uncertainty of being asymptomatic or pre-symptomatic, they stay away from other people so as to prevent the risk of spreading the infection.

In both cases people are likely staying at home, keeping away from others: knowing the right term to use is but a formality.