Qualified immunity

MARY REICHARD, HOST: Coming up next on The World and Everything in It: natural immunity.

It’s hard to know with precision how many Americans so far have had COVID-19. Limited access to testing as well as the virus’s wide-range of symptoms means official counts are probably underestimating the number of Americans who’ve had the virus. One study in the journal Nature published in February estimates that up to 70 percent of the country has had it.

NICK EICHER, HOST: Some of those people say their natural immunity should exempt them from having to get a vaccine. But does natural immunity confer the same protection as the vaccines? WORLD’s Sarah Schweinsberg reports.

SARAH SCHWEINSBERG, REPORTER: A few weeks ago, Rashago Kemp began to feel sick. After a couple of days the 37-year-old’s symptoms worsened.

KEMP: Everything just hurt. You had these weird temperature changes where you'd feel really hot, and you'd feel really cold and you feel really hot. Like my appetite went to almost nothing.

He got tested. Positive for COVID-19. Kemp got tested for two reasons. He wanted to be responsible, and he wanted documentation that he had the virus. Kemp wants to prove he has natural immunity.

KEMP: I believe that, you know, natural immunity, especially in people that are young and healthy, like myself, is robust.

Kemp hasn’t gotten a COVID-19 vaccine. He might in the future. But for now, he’d like his natural immunity to excuse him from a potential workplace vaccine mandate.

KEMP: I feel like especially with all the breakthrough cases, that my natural immunity is not only equal to but superior to the vaccinations, and I should get some credit for that.

So far, the Centers for Disease Control and Prevention doesn’t want to give people credit for natural immunity. The agency recommends COVID-19 vaccines as the best way to protect against the virus—whether you’ve had it or not.

Many companies, schools, and businesses with vaccine mandates are following that guidance, only allowing vaccines to count as protection from COVID-19. And they’re giving out medical exemptions sparingly.

To back its position, the CDC cites a study it conducted earlier this summer when the Delta variant was not prevalent in the United States. It looked at patients in Kentucky and found that unvaccinated people are more than twice as likely to get reinfected with COVID-19 than those who are fully vaccinated.

Now, as the Delta variant spreads, the CDC says vaccines are also the best protection against the strain—even though new data shows Pfizer’s jab only stops symptoms in 66 percent of vaccinated people. That is instead of the previous 90 percent.

Dr. Amesh Adalja is a senior scholar at the Johns Hopkins University Center for Health Security. He says despite reduced protection against the Delta variant, vaccines are still doing their most important job.

ADALJA: What we know is that our vaccines are holding up against the Delta variant when it comes to what matters: serious disease, hospitalization, and death.

But Dr. Adalja believes natural immunity is worth something.

ADALJA: I'm somebody that advocates people who have had some level of immunity be not considered exactly the same as someone who is not vaccinated at all or has no prior immunity. And there is data to suggest that maybe a single dose of the two dose Pfizer and Moderna vaccines may be sufficient for a person with prior immunity to have as robust immunity as someone that's been vaccinated.

New research also points to the benefits of natural immunity, especially against the Delta variant.

An Oxford University study released this month looked at how the Pfizer and AstraZeneca vaccines fared against the strain. The research concluded that people who had been vaccinated and had been previously infected with COVID-19, had the most protection.

And a new study in Israel that isn’t peer reviewed yet looked at 70,000 COVID-19 patients. Researchers found that patients who just got two doses of the Pfizer vaccine were 6 to 13 times more likely to be reinfected than those with just natural immunity. But, again, the strongest immunity was found in those who had been previously infected and had been given at least one dose of a vaccine.

Still, Dr. Adalja says, overall, vaccines provide a more standardized immune response against all of the coronavirus strains than natural immunity alone.

ADALJA: The vaccines contain the genetic material for the spike protein, which causes the immune system to have a very concentrated and effective immune response against the spike protein, which seems to be the most important aspect of our immunity. And although there's different immunity that's induced when you're naturally infected, it doesn't seem that they're as important as having a really robust response against the spike protein, which is what the vaccine delivers.

But some countries are treating natural immunity as equal to vaccines—at least for now. Italy requires a digital green pass to enter public places like restaurants, museums, and gyms. Who's eligible for a pass?

Doug Badger is a public policy analyst at the Heritage Foundation.

BADGER: Two groups of people. One, those who have been vaccinated, and two, those who have certification that they have recovered from the infection within the past six months.

After six months, the country no longer counts a recovered person as immune. Right now, studies disagree over how long natural immunity lasts, as they are also questioning how long vaccine immunity lasts.

Badger says, like Italy,  naturally immune people should also be allowed to function as normal in the United States. But officials here haven’t made documenting natural immunity a priority.

BADGER: So CDC has never encouraged, for example, a doctor to give a recovered patient, a note or some certification or a local public health agency to give the certification that John Doe recovered from COVID as of June 4, 2021. We have our little CDC cards, those of us who have been vaccinated, but we don't have anything that we carry around to document that we've recovered from infection.

That makes it more difficult for schools, hospitals, and businesses to figure out who falls into what categories: never-infected, recovered, and vaccinated.

But recovered COVID-19 patients like Rashago Kemp and experts like Dr. Amesh Adalja at Johns Hopkins say it would be a system worth figuring out.

ADALJA: If the goal is to protect people against COVID-19, I think that this should be something that we incorporate into guidance. If you have natural immunity, one dose of vaccine. If you don't have natural immunity, two doses of vaccine. If you're immunosuppressed, three doses of vaccine.

Reporting for WORLD, I’m Sarah Schweinsberg.

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