Herd immunity from COVID-19 is a long ways off for the U.S., according to an article from the American Medical Association (AMA), where Executive Vice President and CEO of the AMA James L. Madara, MD said that the nation needs to see roughly 200 million infected and more immunized citizens for the infection chain to be broken.
"We're nowhere near [the numbers needed for herd immunity],” Madara said.
He said that a realistic estimate of the amount of the population infected by the virus needed for herd immunity is 70% or more, and the Centers for Disease Control and Prevention (CDC) has estimated the infected U.S. population at only 9%.
At only 30 million people, even if the infection population doubles in six months, the percent will only reach 20, still far short of the number needed for herd immunity.
Madara said that vaccines could help achieve the percentage of immunity needed, but they aren't perfect.
“Vaccines, and specifically those for airway viruses, aren't 100% effective, and that's why both the FDA [Food and Drug Administration] and the CDC—while they would hope for a vaccine that might be, say, 70% effective—they have set the acceptable target at 50%," he said.
With a significant portion of the U.S. population expected to refuse the vaccine, using it to increase immunity is unlikely.
“This makes the math even more daunting," Madara said. "So, for example, if 20% of the population refused the vaccine, we're now out of the range that gets us to herd immunity."
