Natural Acquisition Versus Vaccine – Which is More Effective?

Making Waves
May 25, 2021 By Jackie Connor

A long-awaited serologic study, organized by a team led by UC Irvine (UCI) faculty Phil Felgner, Ph.D., professor of Physiology and Biophysics at UCI’s School of Medicine and director of UCI’s Vaccine Research and Development Center, has shown some promising results.

The comparative study, which focused on immunity effectiveness of naturally acquiring COVID-19 versus receiving one of the available messenger RNA (mRNA) vaccines, like Pfizer and Moderna, has shown that mRNA vaccines are more effective at immunizing against COVID-19 as well as it’s variants versus natural acquisition of the virus.

“Our results show that both mRNA vaccines are spectacular and essentially equivalent to each other,” said Felgner. “The antibody responses induced by these vaccines can shoot up within days after administration suggesting that the vaccine may be useful as a treatment in people who are beginning to experience [COVID-like] symptoms.”

mRNA vaccines “teach” the body’s cells how to create a protein, according to the Centers for Disease Control and Prevention. Though relatively new technology, the mRNA COVID-19 vaccine injects genetic code that tells the cells to produce the spike protein that surrounds the COVID-19 virus and, according to Felgner’s study — which uses UCI technology available through UCI Beall Applied Innovation’s Research Translation Group — has shown effective results.

hand of a white person whose finger has been pricked by a needle for a blood test

More than 7,000 community volunteers in Santa Ana participated in the research study led by a team of UC Irvine researchers that aims to understand the effectiveness of the COVID-19 mRNA vaccines. Photo: Carlos Puma/Puma Photography

The study, which began in February last year, analyzed two sets of data from 3,000 UCI healthcare workers at the UCI Medical Center in Orange in addition to a 7,000-person study in Santa Ana that compared antibody responses from those that acquired COVID-19 infection naturally and those who received the mRNA vaccines.

Felgner’s Coronavirus Antigen Microarray test, developed in March 2020, identifies people who were exposed to the virus and could have been infecting other people. Most of the people who were infected were not tested for COVID-19 and didn’t know that they had it.

According to Felgner, the antibody response induced from natural exposure is not nearly as high as that induced by the vaccine, so those who had COVID-19 should still get the vaccine to improve their immunity. People previously exposed to the virus respond better to the vaccine and have stronger immunity than those never infected before; however, Felgner says those who never had the virus also will receive much higher antibody levels once they receive the vaccine. The mRNA vaccines’ antibody responses also may protect against emerging variants, said Felgner.

The team is also beginning to gather data from the Johnson & Johnson vaccine and according to Felgner, have noted that the antibody levels induced by this vaccine take longer to develop and are lower than the mRNA vaccines.

“These results are consistent with the lower efficacy reported by the developer and with results showing that vaccines are more susceptible to the variants than the mRNA vaccine,” said Felgner. “That said, there is evidence that the [Johnson & Johnson] vaccine reduces the incidence of severe disease and death. Longitudinal studies underway will indicate how durable the responses are for all of the COVID vaccines.”

The study will be peer-reviewed and will determine how long the antibodies will last in addition to the need for booster shots and will compare the different immune responses from the three available COVID-19 vaccines. The team also plans to study immune-compromised patients, whose results indicate lower antibody levels after being vaccinated.

Learn more about Applied Innovation’s Research Translation Group and available UCI technologies.

All Photos: Carlos Puma/Puma Images

Newsletter Envelope