Coronavirus likely to continue spreading until 70 % of US population is infected, says research  

indica News Bureau-


The novel coronavirus is likely to keep spreading for at least another 18 months to two years until 60% to 70% of the population has been infected, a team of pandemic experts from the US has predicted. The pandemic is likely to last as long as two years and won’t be controlled until about two-thirds of the world’s population is immune, a group of experts said in a report.

Because of its ability to spread from people who don’t appear to be ill, the virus may be harder to control than influenza, the cause of most pandemics in recent history, according to the report from the Center for Infectious Disease Research and Policy at the University of Minnesota. People may actually be at their most infectious before symptoms appear, according to the report.

The report was written by CIDRAP director Michael Osterholm and medical director Kristen Moore, Tulane University public health historian John Barry, and Marc Lipsitch, an epidemiologist at the Harvard School of Public Health, reported Bloomberg.

“When severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)—the virus that causes COVID-19—first emerged in Wuhan, China, in December 2019, even the most experienced international public health experts did not anticipate that it would rapidly spread to create the worst global public health crisis in over 100 years. By January 2020, a few public health officials began sounding the alarm, but it wasn’t until March 11, 2020, that the World Health Organization declared a global pandemic,” said a report ‘COVID-19: The CIDRAP Viewpoint’

“This will take time since limited zero surveillance (provides estimates of antibody levels against vaccine-preventable diseases) data available to date suggest that a relatively small fraction of the population has been infected and infection rates likely vary substantially by geographic area. Given the transmissibility of SARS-CoV-2, 60% to 70% of the population may need to be immune to reach a critical threshold of herd immunity to halt the pandemic,” says the research team.

After locking down billions of people around the world to minimize its spread through countries, governments are now cautiously allowing businesses and public places to reopen. Yet the coronavirus pandemic is likely to continue in waves that could last beyond 2022, the authors said.

“One way to quantify the transmissibility of a virus is to determine the basic reproductive number (R0) for that virus. The R0 is the average number of new infections that result from a single infected person in a wholly susceptible population (Delamater 2019). The R0 can vary by factors that influence the contact rate between people, such as physical distancing strategies and lockdowns aimed at driving the R0 below 1. An R0 below 1 indicates that an outbreak is shrinking rather than expanding since each infected person is subsequently infecting less than 1 other person. While the R0 is not influenced by herd immunity (which is the proportion of the population that is immune to a virus), either generated by natural infection or by vaccination, immunity in the population can influence the effective reproductive number (RE), which is similar to the R0 but does not depend on having a fully susceptible population (Delamater 2019),” the research read.

“Risk communication messaging from government officials should incorporate the concept that this pandemic will not be over soon,” they said, “and that people need to be prepared for possible periodic resurgences of disease over the next two years.”

The researchers also laid out three scenarios for how cases might ebb and flow in the coming months. In the first scenario, the team hypothesizes that the first wave of COVID-19 in spring 2020 is followed by a series of repetitive smaller waves that occur through the summer and then consistently over a 1- to 2-year period, gradually diminishing sometime in 2021. 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 1 to 2 years,” says the report.

The experts say the second scenario may see the first wave of COVID-19 in spring 2020 being followed by a larger wave in the fall or winter of 2020 and one or smaller subsequent waves in 2021. This pattern will require the reinstitution of mitigation measures in the fall in an attempt to drive down the spread of infection and prevent healthcare systems from being overwhelmed, they anticipate.

A third scenario is where the first wave of COVID-19 in spring 2020 is followed by a “slow burn” of ongoing transmission and case occurrence but without a clear wave pattern. According to the experts, 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,” they recommend.

“Whichever scenario the pandemic follows (assuming at least some level of ongoing mitigation measures), we must be prepared for at least another 18 to 24 months of significant COVID-19 activity, with hot spots popping up periodically in diverse geographic areas. As the pandemic wanes, it is likely that SARS-CoV-2 will continue to circulate in the human population and will synchronize to a seasonal pattern with diminished severity over time, as with other less pathogenic coronaviruses, such as the beta coronaviruses OC43 and HKU1, (Kissler 2020) and past pandemic influenza viruses have done,” the research concluded.

Developers are rushing to make vaccines that may be available in small quantities as early as this year.

The course of the coronavirus pandemic also could be influenced by a vaccine, but a vaccine may not be available until at least some time in 2021. “And we don’t know what kinds of challenges could arise during vaccine development that could delay the timeline,” says the team.  While large amounts of a vaccine against the 2009-2010 flu pandemic didn’t become available until after the outbreak peaked in the U.S., one study has estimated that the shots prevented as many as 1.5 million cases and 500 deaths in that country alone, the report said.

According to the research team, states, territories, and tribal health authorities should plan for the worst-case scenario — which involves a large second peak of cases in the fall of 2020, including no vaccine availability or herd immunity.

The experts suggest that government agencies and healthcare delivery organizations should develop strategies to ensure adequate protection for healthcare workers when disease incidence surges. Government officials should develop concrete plans, including triggers for reinstituting mitigation measures, for dealing with disease peaks when they occur, they add. “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 over the next years,” the team emphasizes.