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Experts say herd immunity is a long ways off for COVID-19, so behaviors such as mask-wearing and maintaining physical distance are still the best ways to stop the spread of the disease. Getty Images
  • Experts say we’re nowhere close to achieving herd immunity against COVID-19 in the United States.
  • In addition, a new study suggests that antibodies developed during an infection may only last for a few months.
  • Experts say personal behaviors, such as wearing masks, washing hands, and physical distancing, are the best ways to stop the spread of COVID-19.

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More than 3 million people in the United States have received a diagnosis of COVID-19, and more than 136,000 have died since the pandemic began, according to Johns Hopkins.

With so many people contracting the new coronavirus, you might be tempted to think we’re close to achieving herd immunity protection, which would help stop the virus from spreading.

But experts Healthline spoke with say we’re not even close. To get there, we would need 60 to 70 percent of the population to get an infection.

“We are a ‘traveling to Mars length’ away from achieving herd immunity,” said Dr. Gregory A. Poland, an expert on vaccines and a professor of medicine at the Mayo Clinic in Minnesota.

“What we do know is that the majority of Americans have not been infected. We’re very, very far from the majority,” added Gypsyamber D’Souza, PhD, a professor of epidemiology and international health at the Johns Hopkins Bloomberg School of Public Health in Maryland.

“There are hot spots where the outbreak has been heavier, but even in the most heavily exposed places we know about so far, nowhere, no city has gotten anywhere close to herd immunity,” D’Souza told Healthline.

“Very few places have antibody levels greater than 20 percent, and herd immunity is likely to require around 60 percent protection,” noted Dr. David W. Dowdy, who’s also an associate professor of epidemiology and international health at Johns Hopkins Bloomberg School of Public Health.

“Take Italy and look at the hardest hit city. They’ve done seroprevalence studies. It was 12.6 percent,” Poland told Healthline. “An uncontrolled number of deaths and yet it only reached about 13 percent. That’s a long way from 70 percent.”

“We’ve watched real-time demonstrations of this in Sweden, for example,” Poland explained. “They decided to establish herd immunity by just letting everybody get infected. They’ve had, compared to any of the countries around them, many fold higher case rates and deaths. They’ve had the same effect on their economy, and they are nowhere near herd immunity.”

Poland adds it’s not just about the death rate. The virus also seems to bring long-term complications, some of which scientists are just now learning about.

“A naïve public looks at the death rate and says it’s only killing 2 percent,” Poland said. “But there’s very early evidence that lack of symptoms should not be equated with lack of harm. There may well be pulmonary fibrosis, liver and kidney damage, myocarditis, cardiomyopathies with decreased cardio respiratory fitness.”

A new study suggests the immunity a person gets from having had an infection could disappear within a few months, and you could contract another infection.

Which means herd immunity might be elusive.

“If antibody protection doesn’t last long, meaning less than a few months, then it’s unlikely we will achieve herd immunity from natural infection,” Dowdy said.

The recent study hasn’t yet been peer-reviewed, but researchers at King’s College London tested 96 patients and healthcare workers confirmed to have had COVID-19 for antibodies.

The researchers did repeat tests between March and June. They found that the antibody levels peaked 3 weeks after symptoms began but then drastically fell.

With more severe cases of COVID-19, the antibody levels were higher and lasted longer.

In some milder cases, antibodies weren’t even detected.

Experts say the best case scenario is changing our personal behaviors, such as wearing a mask, physical distancing, and washing our hands, until there’s a vaccine and antiviral medications.

“I would say the primary factor, the scariest part about this, is human behavior. So for people who deny science, they have sparked unbelievable, raging, out-of-control outbreaks in the whole southern rim of the U.S.,” Poland said.

“For governments and states that have taken it seriously — let’s choose as our poster child, New York — they did not respond well initially. They became the epicenter, realized what was happening, and basically turned it around very quickly, such that they have essentially very few cases now,” he added.

“We’ve learned a lot. We’re getting better at treating, better at testing. We’re in a stronger position, but this is a very scary time right now,” D’Souza said. “Rates are increasing and are so much higher than we wanted. The risk of what is to come is very scary for those of us who follow infectious disease.”

“These increasing infection rates are going to lead to waves of increasing morbidity, which are adverse health outcomes as well as death. That’s coming and, you know, each of those lives is a person,” she added.

“It’s just really overwhelming to think about death on the scale that is possible with this infection,” D’Souza said.