Immunity to Covid by infection or vaccination: are they equal?

Dr Aaron Kheriaty, professor of psychiatry at the University of California, Irvine, felt he did not need to be vaccinated against Covid-19 because he had fallen ill with the disease in July 2020.

So, in August, he filed a lawsuit to end the university system’s immunization mandate, claiming that “natural” immunity had given him and millions of others better protection than any vaccine.

A judge last week dismissed Kheriaty’s request for an injunction against the university over his tenure, which took effect on September 3. While Kheriaty intends to pursue the case, legal experts doubt his lawsuits and similar lawsuits in the country will ultimately succeed.

That being said, a growing body of evidence shows that contracting SARS-CoV-2, the virus that causes Covid-19, is generally as effective as vaccination at boosting your immune system to prevent disease. Still, federal officials have been hesitant to recognize any equivalence, citing the wide variation in the immune responses of Covid patients to infection.

Like many litigation during the Covid pandemic, the uncertain value of a previous infection has sparked legal challenges, marketing offers and political wrangling, even as scientists work quietly in the background to unravel the facts.

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For decades, doctors have used blood tests to determine whether people are protected against infectious diseases. Pregnant women are tested for anti-rubella antibodies to make sure their fetuses will not be infected with the rubella virus, which causes devastating birth defects. Hospital staff are screened for antibodies against measles and chickenpox to prevent the spread of these diseases. But immunity to Covid seems more difficult to discern than immunity for these diseases.

The Food and Drug Administration has cleared the use of Covid antibody tests, which can cost around $ 70, to detect past infections. Some tests can distinguish whether the antibodies are from infections or from vaccines. But neither the FDA nor the Centers for Disease Control and Prevention recommend using the tests to assess whether you are, in fact, immune to Covid. For this, testing is essentially unnecessary, as there is no agreement on the amount or types of antibodies that would signal protection against the disease.

“We do not yet fully understand what the presence of antibodies tells us about immunity,” said Kelly Wroblewski, director of infectious diseases at the Association of Public Health Laboratories.

Likewise, experts disagree on the protection offered by infection.

How does natural immunity compare to vaccination?

In the absence of certainty and as vaccination mandates are imposed across the country, lawsuits seek to pressure the issue. People who claim that vaccination warrants violate their civil liberties argue that the immunity acquired by infection protects them. In Los Angeles, six police officers sued the city, claiming they had natural immunity. In August, law professor Todd Zywicki alleged that George Mason University’s vaccination mandate violated his constitutional rights, as he enjoys natural immunity. He cited a number of antibody tests and the medical opinion of an immunologist that it was “medically unnecessary” for him to get the vaccine. Zywicki dropped the lawsuit after the university granted her a medical exemption, which she said was unrelated to the lawsuit.

Republican lawmakers have joined the crusade. The GOP Doctors Caucus, made up of Republican doctors in Congress, urged those wary of vaccinations to instead seek antibody tests, contradicting CDC and FDA recommendations. In Kentucky, the state Senate passed a resolution granting equal immunity status to those who show proof of vaccination or positive antibody tests.

Hospitals were among the first facilities to force vaccinations on their frontline workers because of the danger that they could transmit the disease to vulnerable patients. Few have offered exemptions to those previously infected. But there are exceptions.

Two hospital systems in Pennsylvania allow clinical staff to defer vaccination for one year after testing positive for Covid. Another, in Michigan, allows employees to opt out of vaccination if they show evidence of infections and positive antibody tests within the previous three months. In these cases, the systems have indicated that they are keen to avoid staff shortages that could result from the departure of nurses who avoid vaccines.

For Kheriaty, the question is simple. “Research on natural immunity is now pretty definitive,” he told KHN. “It’s better than the immunity conferred by vaccines.” But such categorical statements are clearly not shared by most members of the scientific community.

Dr. Arthur Reingold, an epidemiologist at the University of California at Berkeley, and Shane Crotty, a virologist at the respected La Jolla Institute for Immunology in San Diego, testified as expert witnesses in Kheriaty’s trial, asserting the extent of immunity against reinfection, especially against newer variants of Covid, is unknown. They noted that the vaccination gives a huge boost to the immunity of people who have already been ill.

Yet not everyone who pushes for acknowledgment of past infection is immunization critics or torchbearers of the anti-vaccine movement.

Dr Jeffrey Klausner, clinical professor of population science and public health at the University of Southern California, co-authored a review published last week that showed the infection typically protects for 10 months or more . “From a public health perspective, denying jobs, access and travel to people who have recovered from the infection does not make sense,” he said.

In his testimony against Kheriaty’s case for “natural” immunity, Crotty cited studies of the massive Covid outbreak that swept through Manaus, Brazil earlier this year that involved the gamma variant of the virus. One of the studies estimated, based on donated blood tests, that three-quarters of the city’s population had already been infected before the arrival of gamma. This suggested that a previous infection might not protect against new variants. But Klausner and others suspect that the rate of previous infections presented in the study was a gross overestimate.

A large August study in Israel that showed better protection against infection than vaccination could help reverse the trend toward acceptance of a previous infection, Klausner said. “Everyone’s just waiting for Fauci to say, ‘A past infection offers protection,'” he said.

When Dr Anthony Fauci, the top federal infectious disease expert, was asked in an interview with CNN last month whether those infected were as well protected as those who were vaccinated, he defended himself. “There could be an argument” that they are, he said. Fauci did not immediately respond to a request from KHN for further comment.

CDC spokeswoman Kristen Nordlund said in an email that “current evidence” shows great variation in antibody responses after infection with Covid. “We hope to have additional information on the protective power of vaccine immunity over natural immunity in the coming weeks,” she said.

A “monumental effort” is underway to determine what level of antibody is protective, said Dr Robert Seder, head of the cell immunology section at the National Institute of Allergy and Infectious Diseases. Recent studies have looked at a number.

Dr George Siber, a vaccine industry consultant and co-author of one of the papers, said antibody testing would never provide a yes or no answer on Covid protection. “But there are people who will not be vaccinated,” he said. “Trying to predict who is low risk is a laudable endeavor.”

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