According to a team of pandemic experts in a report released on Thursday, COVID-19 is likely to keep spreading for at least another 18 months up to 2 years. Controlling the spread of the virus will not be possible unless two-thirds or 60% to 70% of the world's population becomes infected or immune.

They predicted that a second wave of coronavirus infections would happen in fall and winter. They advised the US to prepare for a worst-case scenario; however, even in the best-case scenario, people are still likely to die from the infection.

The Center for Infectious Disease Research and Policy (CIDRAP) at the University of Minnesota, said that the idea that the virus is going to stop soon defies microbiology because of its ability to spread from asymptomatic people, which makes it harder to control compared to influenza.

Governments around the world are slowly and cautiously allowing businesses and public places to reopen, after the lockdown measures to minimize the chances of coronavirus from spreading.

Hoping for herd immunity

Since COVID-19 is a new disease, no one has the immunity of it. The researchers' predictions are different from the models presented by the University of Washington's Institute for Health Metrics and Evaluation (IHME) as well as the Imperial College London's model.

The two groups reported that their models predicting millions of death in the US and UK helped stimulate both governments to respond to the growing concern of the pandemic.

Historical reports from past pandemics were used by the CIDRAP -led the team and published reports about the medical details of COVID-19 to produce their calculations.

Harvard School of Public Health epidemiologist Marc Lipsitch said, that when trying to understand how the infectious disease is going to unfold, previous data should be used as well as models. For example, COVID-19 does not die down in the summer, unlike the seasonal flu.

COVID-19 is easily transmitted than flu because novel coronavirus has a longer period of incubation, more asymptomatic spread, and requires a higher herd immunity level.

A higher immunity requirement means that more people will need to get infected and become immune before the pandemic can finally end. The most recent flu pandemics are saying that ending COVID-19 could take another 18 to 24 months.

Preparing for the worst-case scenario

They recommended that governments stop telling their citizens that the pandemic could be ending any time soon and instead prepare their people for a long haul.

According to the researchers, three scenarios are possible to happen:

Scenario one, the first wave of COVID-19 in spring 2020, is followed by a series of repetitive smaller waves that could happen over summer and then consistently over the next two years, gradually lessening sometime in 2021.

Scenario two, the first wave of coronavirus, is followed by an even larger wave by autumn or winter and one or more smaller waves in 2021. Researchers said that the pattern would require the reinstitution of mitigation measures during autumn to lessen the spread of the infection and prevent the healthcare systems from being overwhelmed. This pattern is the same as what happened during the 1918 to 1919 pandemic.

Scenario three, there will be a "slow burn" of the ongoing spread of the virus, which will not require the reinstitution of mitigation measures, although cases and deaths will continue to occur.

The researchers advise the government officials to prepare for scenario two, the worst-case scenario. They should develop concrete plans for dealing when disease peaks occur.

Experts are worried by the decision of officials in lifting the restrictions. They think it is an experiment that can cost lives, especially in places that do it without careful controls in trying to figure out the right time to impose restrictions.

A vaccine could help, but it will not be likely available until at least some time in 2021, the researchers note. There could be more challenges along the way during vaccine development that could delay its timeline.