While there is much epidemiologists are still discovering about the Covid-19 coronavirus, one stark reality is becoming increasingly clear – it's not going away anytime soon.
A new study from the University of Minnesota, conducted with the help of pandemic researchers from Harvard, has produced three likely scenarios for the behaviour of Covid-19.
It paints a troubling picture of the months ahead, including the possibility of a severe second wave in North America that eclipses the first, and the potential need for a reintroduction of strict public health measures.
The report suggests "risk communication messaging from government officials should incorporate the concept that this pandemic will not be over soon and that people need to be prepared for possible periodic resurgences of disease".
Regardless of which of the three scenarios models show could play out, the study warned the coronavirus pandemic will last for 18 to 24 months more.
It comes as the World Health Organisation (WHO) predicted the global number of infections will reach 10 million in the next week.
WHO director-general Tedros Adhanom Ghebreyesus has recently warned the number of new cases being reported was increasing exponentially.
"In the first month of this outbreak, less than 10,000 cases were reported to WHO. In the last month, almost four million cases have been reported," Dr Tedros said.
Scenario one predicts "a series of repetitive smaller waves that occur" after the current first wave.
Those smaller waves would begin imminently and continue over the next 12 to 24 months, gradually diminishing some time in 2021, the report said.
"The occurrence of these waves may vary geographically and may depend on what mitigation measures are in place and how they are eased.
"Depending on the height of the wave peaks, this scenario could require periodic reinstitution and subsequent relaxation of mitigation measures over the next (one to two years)."
The worst-case scenario is the second, labelled a "Fall Peak" that could occur in the northern hemisphere's autumn months, from September to December.
"This pattern will require the reinstitution of mitigation measures in (northern autumn) in an attempt to drive down spread of infection and prevent healthcare systems from being overwhelmed," the University of Minnesota report said.
Scenario two most closely mirrors what occurred during the deadly Spanish Influenza outbreak in 1918 and 1919.
Historic flu pandemics provide a solid model for plotting what Covid-19 might do because of the likely lack of a vaccine until at least 2021, as well as the propensity for one-quarter of those infected to show no symptoms.
The easy transmission of coronavirus, coupled with its highly infectious nature, also make the Spanish flu outbreak a reliable comparison for modelling.
The final model, labelled "Scenario three", outlines one that hasn't been seen before in pandemics.
It plots that the first wave of Covid-19 would be followed by a "slow burn" of ongoing transmission and case occurrence, but without a clear wave pattern.
"Again, this pattern may vary somewhat geographically and may be influenced by the degree of mitigation measures in place in various areas. While this third pattern was not seen with past influenza pandemics, it remains a possibility for Covid-19.
"This third scenario likely would not require the reinstitution of mitigation measures, although cases and deaths will continue to occur."
Whichever scenario eventuates, the report warns that the United States – and indeed the world – "must be prepared for at least another 18 to 24 months of significant Covid-19 activity".
"The virus caught the global community off guard, and its future course is still highly unpredictable," the report said.
"There is no crystal ball to tell us what the future holds and what the 'end game' for controlling this pandemic will be."
Another lesson from the Spanish flu pandemic in the US was the effectiveness of social distancing measures, and the dangers of lifting them too quickly.
In cities where bans were lifted too soon when the curve looked to have been flattened, infections soared shortly after.
Despite efforts around the world to slow the spread of coronavirus, figures from Johns Hopkins University in Baltimore, Maryland, reveal it took 100 days for worldwide cases to reach one million, but only six days for them to go from eight million to nine million.
The pace shows no sign of slowing, with the WHO saying the pandemic is yet to peak in a number of countries.
In the United States, new Covid-19 cases have surged to the highest level in two months.
According to figures compiled by Johns Hopkins University on Tuesday reported 34,700 new virus cases.
The US has more known cases of coronavirus than any other country, with more than 2.4 million people infected and more than 124,000 dead.
Meanwhile, health experts in the United Kingdom have warned there's a "real risk" of a second wave and said "substantial challenges" exist in responding to it.
In an open letter to political leaders, the group, which includes the heads of the Royal College of Physicians, Surgeons, GPs and Nursing, and the British Medical Association, called for a cross-party commission representing all four nations of the UK "that could rapidly produce practical recommendations for action".
The WHO has also expressed alarm about the rate of infections seen in Brazil, which recorded more than 36,000 new cases on Monday.