A new report from the University of Minnesota’s Center for Infectious Disease Research and Policy (CIDRAP) brings some grim news to light. The pandemic may last anywhere from 18 to 24 months.
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The CIDRAP report draws on the similarities and differences of incubation period, asymptomatic rates, and basic reproductive number (R0), between influenza viruses and the novel coronavirus (SARS-Cov-2) to inform a timeline for the COVID-19 pandemic. The report attributes the ease at which COVID-19 has spread to “a longer incubation period, more asymptomatic spread, and a higher R0 [than the influenza virus],” which, in turn, means that the pandemic will remain for a longer period than expected, before the population can develop herd immunity.
When can we start seeing herd immunity for COVID-19?
“It likely won’t be halted until 60% to 70% of the population is immune,” according to the report. This translates roughly to 1.5–2 years. This is on par with previous findings from Harvard T. H. Chan School of Public Health that suggest that social distancing may need to continue until 2022.
In March, Prof. Dr. Lothar Wieler, president, Robert Koch Institute, Berlin, Germany, announced in a press conference that the pandemic would likely last 2 years. He noted that, by the end of the pandemic, approximately 60% to 70% of the world’s population would have been infected with SARS-CoV-2, recovered, and developed immunity to COVID-19.
There is a caveat, however, Dr. Wieler noted. The proposed 1- to 2-year pandemic timeline would depend on how quickly a vaccine could be developed and distributed. But, as an RNA virus that is subject to mutation, many wonder: By the time it’s developed, would a vaccine even work? Supposedly so.
According to the experts, although COVID-19 is, in fact, mutating, it seems to be doing so at a much slower rate than would be considered alarming. In fact, John Rose, PhD, Professor Emeritus, senior research scientist, Department of Pathology, Yale Medicine, who is currently working on a COVID-19 vaccine—one that builds on his previous work of a SARS vaccine in response to the 2003 epidemic—stated, “The sequences of the original isolates [of COVID-19] from China are very close to those in viruses circulating in the US and the rest of the world.”
How will the next 1–2 years play out?
The CIDRAP report offers three distinct scenarios detailing the possible course of the pandemic:
in the first scenario, “a series of repetitive smaller waves” will occur throughout the summer and consistently over a 1–2 year period. The waves will vary across the country depending strongly on “what mitigation measures are in place and how they are eased,” ie, which states lift lockdown measures and ease social distancing. If this scenario plays out, it may require on-and-off implementation of safety precautions, such as social distancing, lockdowns, and isolation of exposed and infected individuals. Under this scenario, the pandemic would likely halt some time in 2021.
The second scenario is similar to what was observed with the 1918 flu pandemic, in which a large wave in the spring was followed by a larger, more dangerous wave in the fall of 1918, and a third wave in the winter and spring of the following year. Here, the first COVID-19 wave is followed by one much larger wave in the fall or winter of the same year. Then, one or more waves, smaller than the first wave, would follow in 2021. In this case, states will have to re-implement safety precautions—such as those listed above and currently instilled in many states today—to control the outbreaks, drive down infection spread, and prevent the healthcare system from being overwhelmed.
The final scenario is much more nuanced. Here, the first wave of spring 2020 would be “followed by a ‘slow burn’ of ongoing transmission and case occurrence, but without a clear wave pattern.” Much like with the first scenario, the outbreaks will vary geographically, depending on safety precautions implemented in each state or region. Fortunately, this scenario would not require strict safety precautions; however, new cases and deaths will continue to appear. Although this scenario has not played out in the past with similar pandemics, the report notes that it remains a possibility.
The CIDRAP report authors concluded, “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 synchronise to a seasonal pattern with diminished severity over time, as with other less pathogenic coronaviruses, such as the beta coronaviruses OC43 and HKU1, and past-pandemic influenza viruses have done.”
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