Over 80 researchers said that the idea of herd immunity is a dangerous notion unsupported by the scientific evidence.

A community is considered to have herd immunity when enough people have built up a protection against a pathogen.

This is through natural infection or through a vaccine.

For instance, in measles, which is an extremely contagious virus, about 90 percent of the community needs to be protected to prevent transmission.

As of now, no one knows exactly how many people need to be protected to stop the COVID-19 pandemic from spreading.

However, USA Today report said that estimates stand from 50 to 70 percent of the population.

Meanwhile, the World Health Organization's director general warned that herd immunity is neither an effective nor an ethical strategy for curbing the COVID-19 pandemic.

Dr. Tedros Adhanom Ghebreyesus warned that the discussions of reaching "herd immunity" had misunderstood what the concept means.

"Herd immunity is a concept used for vaccination, in which a population can be protected from a certain virus if a threshold of vaccination is reached," he was quoted in a Fortune report.

Ghebreyesus added that in other words, herd immunity is achieved by protecting people from a virus, not by exposing the population to it.

Herd immunity has never been used as a strategy to face an outbreak or a pandemic, he said.

Ghebreyesus said it is scientifically and ethically problematic.

The WHO director-general said that is because not much is known yet about the immunity to COVID-19.

He added that it was still not clear how lasting the effects an immune response is.

Ghebreyesus added that some people have also been reinfected.

The WHO still relies on targeted approach.

This includes well-functioning systems to trace, test, and isolate cases of COVID-19 before they spread.

According to Johns Hopkins data, the U.S. now counts more than 7.8 million cases, with 216,000 deaths.

Experts said that the Trump administration should instead promote public health measures such as wearing masks, frequent washing of hands, and social distancing.

These measures should be done instead of pushing for herd immunity.

The 80 signatories, composing various infectious disease experts, said that we cannot afford distractions that undermine an effective response to the pandemic.

COVID-19 Reinfections

A 25-year-old man in Nevada was the first person in the United States to confirm to have contracted COVID-19 twice.

His second infection was worse than the first. Reports said that the Nevada man has recovered.

Recently, an elderly Dutch woman has become the first known to die after testing positive for COVID-19 twice.

The woman was known to suffer from a rare type of bone marrow cancer.

However, researchers said that her immune response could have been enough to fight off the disease.

Scientists must look at the genetic code of the virus from each round of illness, as well as prove they are distinct to confirm reinfection, according to The Guardian.

Health experts said that vaccine developers should factor in the reinfections in the making of a COVID-19 vaccine.

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Herd Immunity Slows COVID-19 Pandemic