Herd immunity is once again becoming a trending topic, but this time, it is because of the fluctuating percentages to achieve that important milestone.
Over the weekend, White House coronavirus advisor Dr. Anthony Fauci contended that the percentage of the population that would need to be vaccinated against the novel coronavirus in order to achieve herd immunity would range “between 70 and 85 percent.”
Previously, the director of the National Institute of Allergy and Infectious Diseases said 70 to 75 percent.
“We have to realize that we have to be humble and realize what we don’t know. These are pure estimates and the calculations that I made, 70 to 75 percent, it’s a range. The range is going to be somewhere between 70 and 85 percent,” Fauci said in an interview on CNN’s State of the Union.
“I made a calculation that COVID-19, SARS-CoV-2, is not as nearly as transmissible as measles. Measles is the most transmissible infection you can imagine. So, I would imagine that you would need something a little bit less than the 90 percent, that’s where I got to the 85.”
He later added: Everyone has to be “honest and humble, nobody really knows for sure, but I think 70 to 85 percent for herd immunity for COVID-19 is a reasonable estimate. And in fact, most of my epidemiology colleagues agree with me.”
This herd immunity approach aims to have enough people within a population become immune to a disease, often through vaccination or natural infection, to make its spread unlikely. As a result, the entire community is protected, even those who are not themselves immune, according to Harvard Medical School.
Dr. Wes Van Voorhis, professor of allergy and infectious diseases at the University of Washington and director of the Center for Emerging and Re-emerging Infectious Diseases, told The National Interest that he believes that herd immunity could be achieved by the end of next year.
However, if “it’s really more than 80 percent, it’s going to take longer,” he said. “The percentage goes higher if a virus is transmitted more easily. So, if the mutant viruses circulating in the United Kingdom or South Africa really transmit easier, and they become widespread here, then the percentage to achieve herd immunity becomes higher.”
Van Voorhis also asserted that the general population still needs to steadfastly follow public health measures, even with the rollout of effective vaccines.
“If people stop wearing masks and stop social distancing, the percentage to achieve herd immunity becomes higher,” he said.
Dr. Lee Riley, a professor and chair of the Division of Infectious Disease and Vaccinology at the University of California, Berkeley, told The National Interest that achieving herd immunity depends on numerous factors, such as “the number of doses and speed at which the vaccines can be produced by the vaccine companies; the number of the types of vaccines in addition to the mRNA vaccines that receive emergency use authorization by the FDA; the speed and efficiency in each state to implement the vaccine distribution; the proportion of the U.S. population willing to accept the vaccine; assumption that the virus remains susceptible to the neutralizing antibodies induced by the approved vaccines; and assumption that no major adverse events are associated with the approved vaccines.”
“If all of these factors go well, I would expect the U.S. to achieve herd immunity by the end of 2021,” Riley said.
Ethen Kim Lieser is a Minneapolis-based Science and Tech Editor who has held posts at Google, The Korea Herald, Lincoln Journal Star, AsianWeek, and Arirang TV. Follow or contact him on LinkedIn.