Breakthrough Infections May Lead to 'Super Immunity' From COVID: Study

Breakthrough COVID-19 cases—that is, infections in people who have been vaccinated—"greatly enhance immune response to variants of the virus," a new study has found.

The study, conducted by researchers at Oregon Health & Science University, found that a breakthrough infection "generates a robust immune response against the delta variant," according to a summary of the findings. Researchers also believe that the immune responses from breakthrough infections caused by other variants, such as Omicron, will be similar.

The study discovered that antibodies in blood samples of those who experienced breakthrough cases were as much as 1,000 percent more effective than those generated two weeks after the second dose of a Pfizer vaccine.

"You can't get a better immune response than this," said Fikadu Tafesse, a senior author of the study and an assistant professor of molecular microbiology and immunology in the Oregon Health & Science University School of Medicine.

"These vaccines are very effective against severe disease. Our study suggests that individuals who are vaccinated and then exposed to a breakthrough infection have super immunity," Tafesse added in a statement.

The findings could show "an eventual end game" for the pandemic, added Marcel Curlin, a co-author of the study and associate professor of infectious diseases at the school. "It doesn't mean we're at the end of the pandemic, but it points to where we're likely to land: Once you're vaccinated and then exposed to the virus, you're probably going to be reasonably well-protected from future variants."

"Our study implies that the long-term outcome is going to be a tapering-off of the severity of the worldwide epidemic," he added.

Researchers did not specifically examine the Omicron variant, which was first detected in South Africa in November and is now circulating throughout the U.S. But Tafesse said they "would anticipate that breakthrough infections from the omicron variant will generate a similarly strong immune response among vaccinated people."

Scientists are still tracking the new variant, but a South African study on Omicron published this week found that it appears to be more resistant to vaccines, while causing less severe illness than the Delta variant.

The study compared COVID immune response in blood samples from 52 people—all employees of the university. Of those people, 26 had experienced mild breakthrough infections after they were vaccinated. Researchers say the study shows getting vaccinated is a crucial step to ending the pandemic.

"The key is to get vaccinated," Curlin said. "You've got to have a foundation of protection."