Hyderabad: Herd immunity or community immunity, also referred to as herd protection, describes a scenario where a large part of the population is immune to an infection which prevents it from spreading.
A Facebook post which shows a graph from Johns Hopkins University has claimed that the USA has reached herd immunity. The post has notched 3,600 shares
The graph is meant to indicate whether a community is doing enough testing or not. This week, a lengthy Facebook post with 1,55,000 views falsely claimed that a declining positivity rate for COVID-19 tests means the US has reached herd immunity, the point where there is a sufficiently high proportion of immune people in the population to stop the spread of the disease.
Archived claim can be seen here.
The Facebook user, identifying himself as a 'Health Policy Expert' used the graph from Johns Hopkins University's Coronavirus Resource Center to argue that a dip in positive cases as a percentage of total tests indicates the coronavirus is 'petering out.'
"Ask any biostatistician what it means when you test hundreds of thousands of people a day for infectious disease and return a consistently lowering the positivity rate. I'll give you a clue: it means heard (sic) immunity has been reached and the virus is dying out," he said in a message enclosing the graph.
The rate of positive COVID-19 tests in the United States does not indicate that herd immunity has been reached. So, the claim is FALSE.
According to the Associated Press, Dr. Jennifer Nuzzo, the lead epidemiologist on the team who made the graph at Johns Hopkins has said that's not at all what it shows. People were misinterpreting the graph as showing how easily the virus is spreading.
"You can't say this is a measure of the amount of infection that's occurring in the community," Nuzzo said.
The number of positive tests as a percentage of total tests provides insight into whether more testing is needed and which members of the population are being tested, according to Nuzzo's team.
A high positivity rate suggests that a community might be testing mostly the sickest patients, and could be missing milder or asymptomatic cases. A lower positivity rate may indicate a community is also testing patients with milder or no symptoms.
Experts estimate that to achieve herd protection from the new coronavirus through infection, at least 70% of the population in the U.S. i.e. 200 million people would need to have recovered from the COVID-19 and develop antibodies against future infections.
Recent projections range around 50%.
Antibody immunity to COVID-19 may only last for a few months.
Hence, the claim is FALSE.
This fact check has been published as part of the Internews Information Saves Lives: Rapid Response Fund project to NewsMeter