NEW DELHI: In what seems like the most probable scenario emerging from recent studies, covid-19 pandemic is here to stay and may hit in waves over the next two years with hotspots emerging in diverse geographical areas.
The findings were shared by a global team of epidemiologists led by scientists from US-based University of Minnesota and Harvard T H School of Public Health, who studied the possible future course of the outbreak, amid different scenarios.
“No one knows exactly how this virus will behave. But, based on current evidence and on previous influenza pandemics, it looks like, it will last 18-24 months. It won’t be halted until 60-70% of the population is immune," said the team, urging governments to plan for the worst-case scenario, including no vaccine availability or herd immunity.
According to scientists, the outbreak is behaving more like past influenza pandemics, than any coronavirus has to date. Eight major pandemics have occurred since 1700s, and each of those seven had a second substantial peak approximately 6 months after the first peak and their course was not substantially influenced by a vaccination campaign, except for the 2009-10 pandemic.
But, what makes covid-19 more challenging, is that unlike influenza which has an incubation period of one to four days, covid-19 has an incubation period of two to 14 days, allowing the virus to move silently in different populations before being detected. This is aggravated by the fact that large percentage of people tend to remain asymptomatic- showing no symptoms whatsoever.
Those infected are transmitting virus even before they begin to show symptoms, and studies indicate this virus shedding may peak one-two days before the onset of symptoms, making it challenging to trace its spread.
According to the report, there is significant probability 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 one-two year period, gradually diminishing some time in 2021.
Second scenario indicates the first wave is followed by a larger wave in the winter of 2020 and one or more smaller subsequent waves in 2021, similar to what was seen with the 1918-19 pandemic. Or there could be a “slow burn" of ongoing transmission and case occurrence, but without a clear wave pattern.
But, the team highlights that even when 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, and past pandemic influenza viruses have done.
“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 2 years," said the report, published by US-based University of Minnesota.
With global race for vaccine intensifying, scientists say, the course of the pandemic could be influenced by a vaccine, but it will likely not be available until at least some time in 2021 and there is little knowledge of what challenge could arise during development which could delay the timelines.
Similar observations were made by another global group of researchers in journal Science last month, which highlighted the need to maintain social distancing intermittently till 2022 as infections could surge after restrictions are lifted.
“Government officials should develop concrete plans, including triggers for reinstituting mitigation measures, for dealing with disease peaks when they occur, especially protecting their health workers," said the report.