The SARS-CoV-2 virus, responsible for COVID-19, could plague the globe for another two years, a team of US-based pandemic researchers have hypothesised in a new report.
According to the experts' report, which was released on Thursday (US time), the spread of the deadly disease is likely to continue for a minimum of 18 months or a maximum of two years - until 60 to 70 percent of the population has been infected.
The researchers recommended the United States, the country with the highest number of COVID-19 cases and deaths, prepare for a worst-case scenario, which they believe could mimic the devastation of the 1918 influenza pandemic.
"This thing is not going to stop until it infects 60 to 70 percent of people... The idea that this is going to be done soon defies microbiology," Mike Osterholm, the director of the Center for Infectious Disease Research and Policy (CIDRAP) at the University of Minnesota, told CNN.
Osterholm co-wrote the report alongside Harvard School of Public Health epidemiologist and leading pandemic expert Marc Lipsitch; former Centers for Disease Control and Prevention epidemiologist and CIDRAP medical director Dr Kristine Moore; and historian John Barry, who authored the 2004 book The Great Influenza about the 1918 pandemic.
The experts believe the virus will only begin to fade when herd immunity gradually develops in the human population. The concept of 'herd immunity' has been controversially utilised by the Netherlands in their approach to the virus, which focuses on cushioning the economic impacts caused by nationwide lockdowns by shunning common restrictions and adopting an acceptance that people will die.
The researchers drew their conclusions from varying reports by other institutes, a number of which have predicted vastly different outcomes to those in the latest report; published COVID-19 medical information; and historical data based on past pandemics, the latter an imperative element to understanding how the virus could unfold, according to Lipstitch.
He and his co-authors believe the SARS-CoV-2 virus is most comparable to previous pandemic strains of influenza.
"Because of a longer incubation period, more asymptomatic spread, and a higher R0 [the average number of people infected by each patient], COVID-19 appears to spread more easily than flu," says the report.
“A higher R0 means more people will need to get infected and become immune before the pandemic can end... Based on the most recent flu pandemics, this outbreak will likely last 18 to 24 months."
The experts proposed three scenarios as to how the virus could unfold in the US.
The first wave of COVID-19, which has currently infected more than 1.13 million Americans and killed more than 66,360, is followed by a series of repetitive, smaller waves that continue throughout the United States' summer (New Zealand's winter 2020) and consistently over a one-to-two-year period, fading in 2021.
The first wave is followed by a larger second wave in autumn or winter (September 2020 to March 2021) and one or more smaller waves in 2021. The experts say this pattern will be similar to the flu pandemic seen in 1918 and 1919, which infected more than 500 million people worldwide and killed anywhere between 17 and 50 million.
The experts also outlined a scenario where a "slow burn" of ongoing transmission would continue to cause new cases and deaths, but would likely not require the "reinstitution of mitigation measures" - rules designed to control the spread of the outbreak, such as lockdown protocol since under alert level 4 in New Zealand.
However, researchers claim that governments should plan for scenario 2 in order to be prepared for the worst-case scenario.
"Government officials should develop concrete plans, including triggers for reinstituting mitigation measures, for dealing with disease peaks when they occur," the experts wrote.
Both Lipstitch and Osterholm have expressed their doubts at the benefits of lifting COVID-19 response restrictions too early, claiming "the experiment" could cost lives.
The report acknowledged that the course of COVID-19 could be "influenced" by a vaccine, but noted that a vaccine will likely remain unavailable until at least 2021 - a date that could be delayed by possible challenges in the development process.