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Fact check: COVID-19 vaccines provide safer, more consistent immunity than infection

The claim: Immunity from infection is always stronger than immunity from vaccines

Millions of Americans are fully vaccinated against the coronavirus, but some anti-vaccine advocates online say they may have been better off getting sick.

The three coronavirus vaccines approved for emergency use in the United States are safe and effective at preventing serious COVID-19 cases, according to public health officials and peer-reviewed studies. As more Americans have received the vaccines, new COVID-19 cases have declined.

But Melissa Floyd says that immunity may not last very long.

"Natural immunity ALWAYS lasts longer than vac-induced immunity," she wrote in a June 8 tweet, which she also shared on Facebook and Instagram. "For the few vacs that last 10-15 years, natural antibodies would have lasted a lifetime (or close to it). There has never been a pathogen where artificial immunity outperformed natural immunity."

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Floyd is a self-described "informed consent advocate" and co-host of "The Vaccine Conversation" podcast. With episode titles like "Does Vitamin D Work Better than the Flu Shot?" and "The REAL Reason We Are Seeing More Measles," the podcast has been a source of vaccine skepticism and misinformation about coronavirus treatments in the past.

Disinformation aimed at undermining the public's confidence in the coronavirus vaccines has surged online over the past several months. Floyd's claim adds to it by misconstruing what's known about coronavirus immunity.

Experts told USA TODAY both infection and vaccination are protective against the coronavirus. Scientists don't yet know whether natural immunity or vaccine immunity lasts longer, given the limited time COVID-19 has existed. But research suggests vaccination provides more consistent protection against the virus.

While natural immunity tends to provide stronger protection against pathogens than vaccination, Floyd is wrong to say it always does — and getting vaccinated is far safer than getting sick.

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"I am spending too much time debunking COVID falsehoods from the internet, and this is another one," Grant McFadden, director of the Biodesign Center for Immunotherapy, Vaccines and Virotherapy at Arizona State University, said in an email.

Floyd did not respond to USA TODAY's requests for comment.

How immunity works

People acquire disease immunity in two primary ways: infection and vaccination.

When humans are exposed to toxins or disease-carrying pathogens, the body creates antibodies to try to neutralize them. After infection, the body remembers how to create those pathogen-specific antibodies, decreasing the likelihood of future infections.

Vaccines help the body produce antibodies for specific pathogens without infection.

mRNA vaccines work by getting our cells to produce the spike protein free of any virus. The vaccine is protected by a lipid coating. The vaccine enters healthy cells in a process called endocytosis. (TK) Once inside, the cellular machinery produces spike proteins similar to SARS-CoV-2.
mRNA vaccines work by getting our cells to produce the spike protein free of any virus. The vaccine is protected by a lipid coating. The vaccine enters healthy cells in a process called endocytosis. (TK) Once inside, the cellular machinery produces spike proteins similar to SARS-CoV-2.

Most vaccines create what public health officials call an "imitation infection." By introducing to the body inactivated or weakened viruses, or even pieces of viruses, vaccines trigger an immune response.

The COVID-19 vaccines, for example, teach cells how to make spike proteins like those on the surface of the coronavirus. The body then produces antibodies against those proteins, building up immunity for future coronavirus infections.

Natural immunity tends to be stronger

Experts say that, in general, natural immunity does tend to provide stronger protection than vaccines.

"It is true that natural infection almost always causes better immunity than vaccines," Children's Hospital of Philadelphia says on its website. "Whereas immunity from disease often follows a single natural infection, immunity from vaccines usually occurs only after several doses."

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The reason why has to do with exposure.

When someone is vaccinated against a virus, they are only exposed to a portion of that virus or a weakened version of it. When someone gets sick, they're exposed to the entire thing, meaning the immune response — and the symptoms that come with it — tends to be greater. In former COVID-19 patients, for example, "natural immunity is to the entire virus surface and not just the spike protein," Dr. Marty Makary, chief of the Johns Hopkins Islet Transplant Center, told USA TODAY in an email.

But natural immunity isn't a silver bullet.

Marc Bugarin, 15, at a school-based COVID-19 vaccination clinic for students 12 and older in San Pedro, Calif., May 24, 2021.
Marc Bugarin, 15, at a school-based COVID-19 vaccination clinic for students 12 and older in San Pedro, Calif., May 24, 2021.

"There are certainly scenarios where natural immunity is more robust than vaccine-elicited immunity, but no, it's not always the case," Shane Crotty, a professor and vaccine researcher at La Jolla Institute for Immunology, told USA TODAY. "Immunology's complicated."

Immunity depends on virus

In some cases, vaccination works better than natural immunity.

"It depends on the virus," Vincent Racaniello, a microbiology and immunology professor at Columbia University, said in an email. "Many viruses encode proteins that antagonize immune defenses, hence immunity after infection may be suboptimal. Many vaccines eliminate these antagonists, so the immune response may be more durable."

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One example is human papillomavirus (HPV), for which vaccination provides more durable immunity than infection. The vaccine contains a higher concentration of proteins than the actual infection — which evades the body's defenses — eliciting a stronger immune response. Research has indicated that the HPV vaccine lasts at least 10 years.

Vaccines for tetanus and pneumococcal also provide stronger immunity than the infection itself. Those are exceptions, experts say, but the coronavirus is an exceptional pathogen.

"Natural immunity tends to be stronger, yes," Crotty said. "The reasons scientists and public health officials have been more cautious about COVID-19 is because of this big range that we've seen for COVID-19 in people, which seems different than some other infections."

Scientists still studying coronavirus immunity

Eight experts told USA TODAY that while evidence suggests both natural and vaccine immunity to the coronavirus are strong, it's too soon to say which one lasts longer.

First things first: Public health agencies say the coronavirus vaccines are highly effective at preventing serious COVID-19 cases.

Last year, more than 100,000 people participated in clinical trials for vaccines from Pfizer-BioNTech, Moderna and Johnson & Johnson. The first two vaccines were found to be about 95% effective at preventing COVID-19, while Johnson & Johnson's shot was found to be about 72% effective (a number that was lower in part due to the higher volume of COVID-19 cases in the general population during the trial period). Subsequent studies of the vaccines outside of clinical trials support those numbers.

That's the good news. The bad news: Scientists are still working to figure out how long that protection lasts.

"So far, studies of lasting immunity to COVID-19 have been encouraging for both the vaccines and natural infections," Dr. Ellen Foxman, an assistant professor of laboratory medicine and immunobiology at the Yale School of Medicine, said in an email. "However, keep in mind that this virus has only been around since late 2019/early 2020, and vaccines since later in 2020 — so no one can claim to know if immunity lasts for longer than that."

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Pfizer-BioNTech said in April that, according to data from its ongoing clinical trial, its vaccine is about 90% effective against COVID-19 for at least six months. Public health experts have said the protection likely lasts longer, partially because Pfizer reported its vaccine — which uses the same technology as Moderna's shot — didn't lose much of its efficacy after six months.

Early research is promising on the durability of natural immunity, too.

A research article published Feb. 5 in Science magazine found natural immunity can last at least eight months. More recent research, published May 24 in Nature, detected cells producing coronavirus antibodies in patients at least 11 months after they had mild COVID-19 cases.

Makary wrote in a recent Wall Street Journal column that there's "ample scientific evidence that natural immunity is effective and durable." Makary told USA TODAY that, for severe COVID-19 cases, antibody levels are "as high or even higher in some instances than what is seen after vaccinated immunity."

However, the bottom line is that it's too early to say whether immunity from infection is stronger than immunity from vaccination.

"We need robust clinical trials measuring reinfection rates in people who received the vaccine compared to those who got COVID-19 and recovered to really conclude whether or not there is a relevant difference," Cynthia Anne Leifer, an immunology and microbiology professor at Cornell University's College of Veterinary Medicine, said in an email. "Those trials are ongoing, so time will tell."

COVID-19 vaccines offer more consistent protection than infection

While the jury's still out on whether natural immunity or vaccine immunity provides longer-lasting protection against COVID-19, research suggests that, overall, vaccination is the better bet.

Why? Vaccines provide more consistent protection, for starters.

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"Recovery from COVID results in very variable immunity to a second infection, and this is reflected in the wide range of anti-spike antibodies in recovered patients," McFadden said. "On the other hand, the immunity from the vaccines (especially the messenger RNA versions) is much more uniform, both in terms of protection from COVID and in anti-spike antibody levels."

Preliminary research backs that up.

An April 20 paper awaiting peer review — and cited by Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases — found that people who had received two doses of shots from Pfizer or Moderna had antibody levels "up to 10 times" higher than those of a natural infection.

But those natural infection levels vary widely. The same Science magazine paper that found natural immunity lasts at least eight months also found some COVID-19 survivors had immunity levels 100 times higher than other survivors.

"So if you were playing a basketball game and one person scored one point and the other person scored 100 points, you would not consider those equivalent performances," Crotty, one of the paper's co-authors, told USA TODAY. "And so that's the way we think about the immune responses as well. They're there, but not everybody's equal."

People wait in line for a $100 incentive the New Mexico Department of Health offers for getting a vaccine shot at a vaccination event at the Las Cruces Convention Center in Las Cruces on Wednesday, June 16, 2021
People wait in line for a $100 incentive the New Mexico Department of Health offers for getting a vaccine shot at a vaccination event at the Las Cruces Convention Center in Las Cruces on Wednesday, June 16, 2021

Documenting whether people actually had COVID-19 instead of another illness is also a challenge. If you had COVID-19, took an antibody test, and found a "measurable, substantial antibody response, then you're probably fine," Crotty said. But even that's not 100%.

Then there are the coronavirus variants.

"Antibodies elicited by infection do not neutralize the currently circulating coronavirus variants as efficiently as antibodies elicited by mRNA vaccination," Scott Hensley, an associate professor of microbiology at the University of Pennsylvania, said in an email.

Public health officials are monitoring six notable variants circulating in the U.S., all of which appear to spread more easily than other coronavirus strains. It depends on the variant and vaccine, but research indicates the three coronavirus vaccines authorized for emergency use in the U.S. work at least to some degree against the variants.

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"The higher your degree of immune response against the wild-type (coronavirus), the greater the secondary coverage you have against a wide array of variants," Fauci said during a June 8 White House press briefing.

Vaccines are the safer option

Experts and public health officials say vaccination is also a better option than natural infection for the simple reason that someone doesn't have to get sick to reap the benefits.

"To get immunity from a natural infection, you first have to get the infection — and risk a serious illness or having long-term health consequences," Foxman said. "You also risk spreading the virus to friends and loved ones who might get a serious illness, even if you don’t. The main reason to get a vaccine is to get immunity without taking these health risks."

If you've already had COVID-19 — and you can prove your body produced a measurable antibody response — experts still recommend getting at least one vaccine dose.

"My clinical advice to healthy patients with natural immunity is that one shot is sufficient, and maybe not even necessary, although it could increase the long-term durability of immunity," Makary wrote for the Wall Street Journal.

Our rating: Partly false

The claim that immunity from infection is always stronger than immunity from vaccines is PARTLY FALSE, based on our research. While natural immunity tends to last longer than vaccine immunity, experts say it depends on the pathogen. Vaccines for HPV, tetanus and pneumococcal provide stronger immunity than the disease itself. Scientists are still studying the coronavirus, but evidence from experts, public health officials and research suggests COVID-19 vaccines provide more consistent and safer protection than infection.

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This article originally appeared on USA TODAY: Fact check: Vaccines offer safe, consistent protection from COVID-19