Recent research comparing the effectiveness of natural immunity to vaccination has sparked more discussion among experts over how to evaluate viral risk.
As reported by the Daily Caller, the observational study included more than 700,000 Israelis who were divided into three groups: uninfected people who got two doses of Pfizer's COVID-19 vaccine, uninfected people who were never vaccinated, and those who had been infected and had one dose of the vaccine.
The researchers discovered that vaccinated participants with no infections prior to their shots were thirteen times more likely to get a breakthrough infection than those who had previously been sick because of the virus.
"It's a textbook example of how natural immunity is really better than vaccination," said Dr. Charlotte Thålin, an immunology researcher at Danderyd Hospital and the Karolinska Institute in Stockholm, Sweden.
"To my knowledge, it's the first time [this] has really been shown in the context of COVID-19," she reportedly told Science Magazine.
Data was collected in Israel between June 1 and August 14, when the Delta strain was prevalent. It is thought to be the biggest real-world research evaluating natural immunity to vaccination protection undertaken during the outbreak.
The research showed that natural immunity led to fewer symptomatic cases and hospitalizations, in addition to improved protection against reinfection.
The researchers also cautioned against interpreting the study results as if acquiring the COVID-19 virus is a safer alternative to being vaccinated.
"What we don't want people to say is: 'All right, I should go out and get infected, I should have an infection party," said Michael Nussenzweig, an immunologist at Rockefeller University.
Other studies that yielded the same results
The Journal of Infection released a report in December 2020 with results from an investigation into 1,038 U.K. healthcare professionals who had contracted COVID-19 in the first stage of the pandemic. After approximately seven months, the same 128 individuals were re-tested for COVID-19 since they were showing signs of illness. Nevertheless, the tests showed that they had not contracted COVID-19 again.
Another report published by Science in January 2021 showed that 95% of the individuals in the research had three or more components of long-term immunity against the virus six months after contracting COVID-19. That includes antibodies, B cells, and T cells.
"There was a lot of concern originally that this virus might not induce much memory. Instead, the immune memory looks quite good," said Shane Crotty, a Ph.D. molecular biologist and the coauthor of the study.
A study evaluating all known cases of C-19 in Austria from the first two waves of the pandemic was published in the European Journal of Clinical Investigation in February 2021. According to this study, the majority of individuals who were infected with COVID-19 during the initial outbreak acquired a degree of immunity against future outbreaks.
"We observed a relatively low re-infection rate of SARS-CoV-2 in Austria. Protection against SARS-CoV-2 after natural infection is comparable with the highest available estimates on vaccine efficacies," reads the study's conclusion.
The research also discovered that no one who survived COVID-19 in the first wave perished from it in the second wave.