The coronavirus pandemic likely won’t be contained until 70% of the world’s population has been infected and stop the virus through what’s known as herd immunity, a natural process that could take as long as two years, according to new research.
In forecasting COVID-19's spread in the coming months, researchers at the Center for Infectious Disease Research and Policy at the University of Minnesota compared the current outbreak to eight major flu pandemics dating back more than 300 years, according to CBS News.
Nearly all the pandemics studied were found to have a greater second wave of infections that came about six months after the first, while some had “smaller waves of cases over the course of two years.”
Herd immunity refers to the natural resistance to a contagious disease that emerges when a high percentage of people are immune, either through vaccination or prior exposure.
“The length of the pandemic will likely be 18 to 24 months, as herd immunity gradually develops in the human population,” according to the report. “Given the transmissibility of SARS-CoV-2” — the virus that causes COVID-19 — “60% to 70% of the population may need to be immune to reach a critical threshold of herd immunity to halt the pandemic.”
Despite more than 3 million infections reported worldwide, only a small fraction of the overall population has been infected so far. Nearly 65,000 have died so far in the United States.
Scientists also can’t say whether those who have recovered from the disease will be immune in the future or how long such immunity would last.
Last month, Robert Redfield, the director of the Centers for Disease Control and Prevention, said he expects a second wave of the coronavirus to coincide with flu season and warned of the possibility for a much greater toll than the nation has witnessed thus far.