It's impossible to say with any degree of certainty just how long the COVID-19 pandemic that took the world by storm in early 2020 will last.

There are two ways to describe an 'end' to a plague. One is elimination, which is a reduction of new cases to a suitably low number (preferably zero). The other is eradication - a clear, permanent, and complete wiping out of an infectious agent.

While much has been learned about the virus's ability to spread between people, infect cells, and put infected people at risk of a range of major health problems, estimating its duration in a global population depends on how we all behave, which can be much harder to model.

Much as predictions on climate change vary depending on how we act now, it might be possible to propose scenarios that similarly forecast the different futures facing us.

What if we lived in a perfect world?

Taking the actions of nations such as New Zealand and Vietnam as case studies, effective social distancing measures are an effective way to limit the spread of SARS-CoV-2, showing that the virus can be eradicated on at least a local level.

The reasons why people in different communities don't engage in social distancing are complex and varied. Some are influenced by personal, political, and moral values. Others are affected by economic decisions, lacking social welfare to support them.

In a perfect world, where distancing was followed strictly enough to make the number of community transmissions negligible all over the world, the current generation of functioning virus particles would be the last.

SARS-CoV-2 particles would then break down in the air within hours. On surfaces, within just a few days.

Knowing how long the virus persists in a human body is a little harder to pin down. One early study showed it remains viable for about nine days after first symptoms appear, with viral fragments detectable as long as a month later.

In best cases, a month or two of perfect global isolation appears to be enough to clear all humans of the virus for good.

Our world is far from perfect. What's more reasonable?

Without social isolation to reduce the virus's transmission from infected parties, protection from widespread immunity is the next best thing.

This factor depends on how long the average person retains immunity from SARS-CoV-2, a factor that is still unclear. The memory cells that produce antibodies could remain effective for as few as a couple of months, or last as long as a couple of years or more.

A vaccine distributed and delivered within a short enough time frame could force the R (number of people likely to be infected by another infected person) to drop below a figure necessary for the virus to hang around.

While producing vaccines for past coronaviruses was problematic, there has been significant progress for SARS-CoV-2. Early efforts are showing promise, meaning we could optimistically expect moderately effective vaccines to be available by the end of 2020 to early 2021.

If doses could be produced in sufficient quantities - itself a practical and logistical hurdle - they would still need to be distributed into the far corners of the globe. Then there's the question of how many people could (or even would) be vaccinated.

There are few precedents we can look towards. One involved the diplomatic efforts of the World Health Organisation, a program to eradicate smallpox finally succeeded in the late 1970s. The Global Smallpox Program took nearly twenty years to meet its goals, but it also suffered from limited vaccines and low funding.

With enough funds and cooperation, we could feasibly globally eradicate SARS-CoV-2 in years rather than decades.

Will the coronavirus be around forever?

The bleakest of realities is SARS-CoV-2 is here to stay, with reservoirs of the virus being maintained among globally-connected communities for the foreseeable future.

Vaccines will most likely improve in efficiency and production, though human behaviour being what it is, even making them mandatory will make it unlikely they'll be administered in sufficient quantities.

New medications will more than likely help reduce the numbers of deaths and other adverse health effects. Politics, social trends, and new ways of conducting business and domestic living will evolve to reflect individual values towards COVID-19's spread.

Historically, pandemics either fade, as deaths and infections plummet, or we just get used to the ebb and flow of a new disease.

Science can only do so much. The rest is up to a global population of humans who increasingly distrust one another more than they fear a killer virus.

All Explainers are determined by fact checkers to be correct and relevant at the time of publishing. Text and images may be altered, removed, or added to as an editorial decision to keep information current.