Natural Immunity as Good as or Better Than COVID-19 Vaccination: Study

Post-infection immunity is similar or even superior to the protection bestowed by COVID-19 vaccines, according to a new study.

Post-infection protection—known widely as natural immunity—was strong and remained significant over time, researchers found. Against the Wuhan, Alpha, and Delta variants, the protection against re-infection was 85 percent at four weeks, 78 percent at 40 weeks, and 55.5 percent at 80 weeks.

That protection dropped more quickly against the Omicron BA.1 subvariant, declining to 36 percent by 40 weeks, and protection against symptomatic disease also waned below 50 percent.

But shielding against severe disease was strong against all strains, including the BA.1 subvariant, researchers found. The naturally immune enjoyed 88.9 percent protection against BA.1 at 40 weeks, which was actually higher than against earlier strains.

“Our analysis found significantly reduced protection against re-infection from the omicron BA.1 variant but that levels of protection against severe disease remained high,” Dr. Stephen Lim of the Institute for Health Metrics and Evaluation at the University of Washington’s School of Medicine, and his co-authors, said in the study.

Dr. Brett Giroir, a former Trump administration health official whose post on natural immunity was censored by Twitter on behalf of Pfizer board member Dr. Scott Gottlieb, said the study “demonstrates robustness of natural immunity.”

Dr. Vinay Prasad, an epidemiologist at the University of California, San Francisco who was also not involved in the study, said that the paper made a “compelling case that we can effectively stop boosting average risk individuals (most adults) who have had covid.”

“Vaccine policy should have been different in people with prior illness,” Prasad also said.

Public health officials have repeatedly said that vaccination is better than natural immunity, or that the naturally immune should still get vaccinated despite the protection they have. Some other countries have acknowledged natural immunity by lowering the number of recommended doses for the population.

Comparison to Vaccination

The researchers performed a review and meta-analysis by looking for studies on natural immunity conducted through Sept. 31, 2022. Studies were included if a group of naturally immune, unvaccinated people were compared to unvaccinated people who had not been infected. Studies that also included vaccinated people were included if the research also included unvaccinated and naturally immune people. Studies that only had results for natural immunity in combination with vaccination, or hybrid immunity, were excluded.

Researchers performed a modeling technique called Bayesian meta-regression to reach pooled estimates of protection by time since infection.

In total, 65 studies were included in the meta-analysis from 19 different countries. Just 30, though, included information on time since infection, and a subset of those included information on one or more of the outcomes—re-infection, symptomatic disease, and severe disease—during the BA.1 era.

One of the researchers’ main conclusions was that the study showed that natural immunity “is at least equivalent if not greater than that provided by two-dose mRNA vaccines,” or the Pfizer and Moderna messenger RNA vaccines.

That conclusion was supported by references to just two studies—one unpublished paper and one published paper from Qatar that found natural immunity was more protective than the mRNA vaccines. A graph in the study also showed natural immunity conferring better immunity vaccination against infection, symptomatic disease, and severe disease—including against three vaccine doses, or a primary series and a booster.

The researchers also emphasized that COVID-19 can cause problems, including death, but did not mention side effects from vaccination that can also cause long-term issues, including mortality.

Limitations included the low number of studies that were analyzed for the analysis and the reliance on observational studies.

The study was published by The Lancet. Researchers received funding from several sources, including the Bill & Melinda Gates Foundation. Bill Gates, the Microsoft founder, has repeatedly promoted vaccination during the pandemic.

Previous Research

Previous studies primarily found that natural immunity is superior to vaccination, including a study published in January. The U.S. Centers for Disease Control and Prevention (CDC) reported in 2022 that natural immunity was better against Delta. Research has also shown that previous infection doesn’t protect as well against infection over time since Omicron displaced Delta, but remains strong against severe disease.

Protection from vaccines drops sharply within months against Omicron and doesn’t even start that high, according to studies from the CDC and others, and the shielding against severe disease also wanes considerably over time. That’s prompted authorities to recommend multiple booster shots, in a bid to restore the protection, but the protection from boosters also doesn’t last long. Boosters provided little added protection for the naturally immune against BA.1, one study showed.

Updated shots have been introduced in the United States and other countries but no clinical data for the new vaccines are available and observational data is mixed. Federal authorities are trying to move towards a system where a shot is an annual occurrence, but antibody data indicate that may not be enough for everybody.

Researchers in the new study said that policymakers should take into account the protection from prior infection, saying it “supports the idea that those with a documented infection should be treated similarly to those who have been fully vaccinated with high-quality vaccine,” they said.

The United States has never acknowledged natural immunity in its vaccine recommendations, though officials did consider doing so at one point.

The researchers were not able to provide protection estimates against newer strains, like the BA.5 subvariant, due to a limited number of studies. They said that further assessments of natural immunity should be conducted in the future.