GOP lawmakers fight vaccine efforts with dubious 'natural immunity' claims

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Recent research from the CDC shows getting vaccinated provides twice as much protection against the virus as getting infected 'naturally' does.

On Wednesday, Sen. Roger Marshall (R-KS) and 14 other members of the "GOP Doctors Caucus" sent a letter to Centers for Disease Control and Prevention Director Dr. Rochelle Walensky urging her agency to "recognize natural immunity" against COVID-19.

In their letter to the CDC, the group of Republican lawmakers insisted that natural immunity is just as effective as vaccination. But evidence has shown that the COVID vaccine provides a higher level of protection against the virus than getting infected "naturally" does.

A recent CDC study found that Kentucky residents who were unvaccinated and contracted the virus were 2.34 times as likely to get reinfected compared to residents who were fully vaccinated.

"While we have always encouraged and supported COVID-19 vaccinations, never before has it been more important for the U.S. Centers for Disease Control and Prevention (CDC) to recognize natural immunity," the lawmakers wrote.

The letter continued: "It may be the case that it is not medically necessary for an individual to receive a vaccination. It may also be the case that a sufficient level of protection may be produced from one dose."

Several of the letter's claims are dubious at best, and outright false at worst. The vast majority of medical experts recommend that everyone who is eligible should get vaccinated, whether or not they previously contracted the virus.

In their letter, the GOP lawmakers wrote that they have "always encouraged and supported COVID-19 vaccinations." But that's not the case. Sen. Rand Paul (R-KY), who is a licensed ophthalmologist, has spoken publicly about his refusal to get vaccinated, has urged those with prior infections not to get vaccinated, and has gone so far as to suggest that Americans "resist" CDC guidelines intended to help prevent the virus' spread.

Another member of the group, Rep. Ronny Jackson (R-TX) — who previously served as former President Donald Trump's personal physician — has claimed that Americans who contracted the virus naturally could "go on about your life" without getting vaccinated.

The lawmakers' central argument relies on the claim that so-called "natural immunity" is comparable to the protection the COVID vaccine provides. The letter cites several studies showing that individuals who'd previously had COVID developed antibodies that helped prevent them from becoming infected with the virus again.

This claim is true, and data conclusively show that contracting and recovering from COVID equips the immune system with T-cells that can fight off the virus. As a result, COVID reinfections are relatively rare.

Still, those studies say nothing about the relative protection of prior infection versus vaccination. And on this issue, the data is far less clear.

The authors point to several studies which purport to show a similar level of protection from "natural immunity" versus vaccination. Two studies, one in Nature Medicine and one in Science Immunology, show that antibody levels for individuals who had previously been infected with COVID and then received one vaccine dose were similar to those who had never had COVID and received two doses of the vaccine.

In the latter study, the researchers concluded that natural immunity coupled with a single dose of the vaccine could be an effective prevention strategy in "resource-limited settings," such as countries without widespread access to the vaccine.

In the United States, however, COVID-19 vaccines are widely available, meaning there's no reason to conserve doses for those who haven't been previously infected.

Moreover, researchers are still unsure how long natural immunity provides protection against reinfection. Though some studies have demonstrated immunity from prior infection can last upward of eight months, others found a decline in antibodies after just 60 days, particularly when the initial infection did not present with symptoms. With the Pfizer and Moderna vaccines, clinical trials demonstrated strong immunity for at least six months among non-immunocompromised populations.

In a White House COVID briefing on Tuesday, Dr. Anthony Fauci debunked this new line of argument against getting vaccinated.

"You know when you are at herd immunity when the virus doesn't have the opportunity to go from person to person. But right now, we don’t know what that number is. And when you don’t know what the number is, what do you do? You vaccinate as many people as you possibly can, as quickly and as expeditiously as you possibly can. That’s what we should be concentrating on, not any particular number," Fauci said.

The GOP lawmakers also pointed to a new study using data from Israel, which found that individuals who had previously been infected with COVID were less likely to become sick with the coronavirus delta variant than those who hadn't been infected but were vaccinated. But that study, which has not yet undergone peer review, has been criticized by some scientists who've identified possible sources of epidemiological and statistical biases.

According to infectious disease expert Dr. James Lawler, the study suffers from what's known as selection bias. By the time the researchers were examining delta variant infections, vaccines had been widely available in Israel for some time. As such, it could be expected that those who chose to remain unvaccinated were on average younger and healthier than those who'd been vaccinated early on. Though researchers attempted to control for this type of bias, Lawler argues it's impossible to fully eliminate these distinctions given the major differences between the two groups.

Similarly, Lawler points to a problem of survivorship bias in the study — anyone who died as a result of COVID inherently went uncounted in the researchers' study. It's likely the vast majority of those who fell into that category were unvaccinated, biasing the results in favor of those who remained healthy.

The CDC in early August published its own study comparing the benefits of vaccination versus natural infection. Looking at a cohort of Kentucky residents who'd all previously had COVID, the researchers found that those who remained unvaccinated were 2.34 times more likely to become reinfected with the virus than those who'd been fully vaccinated. "This finding supports the CDC recommendation that all eligible persons be offered COVID-19 vaccination, regardless of previous SARS-CoV-2 infection status," the CDC researchers concluded.

Asked about the letter and their prior studies, the CDC did not respond to a request for comment. Reached by email, a spokesman for Marshall provided a long list of studies and articles addressing the protection provided by natural immunity. Responding to the CDC study specifically, an official in the senator's office highlighted possible flaws in its methodology, including that without more detailed demographic data, it's difficult to surmise whether the population analyzed can be representative of the whole country.

"The letter, as written, takes no position on natural immunity over vaccination as different patient populations have varying immune responses, per those identified by health experts to be at risk of severe infection and death," the official said. "The letter requests the agency to build [off] existing studies to determine an individual's level of protection that evidences medical necessity."

Most experts agree that further study about the relative benefits of natural immunity is warranted. But many cautioned against claims that natural immunity is better than vaccination, arguing that could encourage some to actively seek out COVID infection.

"What we don't want people to say is: 'All right, I should go out and get infected, I should have an infection party,'" Dr. Michel Nussenzweig, an immunologist at Rockefeller University, told Science. "Because somebody could die."

Published with permission of The American Independent Foundation.