Social distancing may be required until 2022 to prevent critical care capacities from being exceeded, said a Harvard study published in the journal Science on Tuesday as more coronavirus patients are hospitalized in intensive care units.
"Even in the event of apparent elimination, SARS-CoV-2 surveillance should be maintained since a resurgence in contagion could be possible as late as 2024," the scientists said in their report.
The study was conducted by Stephen M. Kissler and Yonatan H. Grad from Harvard's Department of Immunology and Infectious Diseases, as well as Marc Lipsitch, Christine Tedijanto and Edward Goldstein from the university's Epidemiology department. Grad and Lipsitch are corresponding authors of the report.
Regardless of the transition dynamics of the virus, say the scientists, urgent measures should be taken in order to address the current pandemic. "Vaccines and pharmaceutical treatments may require months to years to develop and test," say the scientists, with the only way to curb the pandemic being non-pharmaceutical interventions.
According to the scientists, SARS-CoV-2, the virus causing the deadly COVID-19 disease, is capable of producing a "substantial outbreak" regardless of the season in all modeled scenarios.
The study found that outbreaks established in the winter-spring, like the one leading to the current COVID-19 pandemic, tend to have lower peaks. Ones occurring in the autumn-winter, on the other hand, are more acute, said the scientists.
It has yet to be determined whether people once infected would be permanently immune to the virus. According to the study, if immunity to the virus is not permanent, it is likely to enter into regular circulation, similar to pandemic influenza (the flu).
It is likely that short-term, 40-week immunity to the virus will lead to annual coronavirus outbreaks. If the immunity is long-term, standing at two years, the outbreaks will likely be biennial, with a major coronavirus outbreak occurring every other year.
As of Wednesday morning, the mortality rate of the COVID-19 disease stands at 6.4%, with close to 127-thousand deaths of nearly two million confirmed cases. By contrast, the mortality rate of the flu in the US stood at stood at 0.096% in the 2018-2019 season, according to the Centers for Disease Control and Prevention (CDC), being nearly 67 times lower than that of the coronavirus.
A 2006 study published by the CDC's Emerging Infectious Diseases journal estimates the mortality of the Spanish Flu to be 10%-20%. Epidemiologist Larry Brilliant, who worked with the World Health Organization to help eradicate smallpox, told CNN in late March that the 1918-1919 pandemic's mortality was 2-10%.
According to the Harvard researchers, even if SARS-CoV-2 immunity will only last for two years, mild, 30%-immunity from other existing strands of coronavirus that usually cause the common cold may effectively eliminate its transmission for up to three years.
Even if the virus does appear to have died out, say the scientists, resurgence in 2024 is likely. According to the researchers, long-term immunity, which could be achieved by vaccination, could potentially lead to the elimination of the virus.