- A recent study investigated how the immune system responds following both SARS-CoV-2 infection and COVID-19 vaccination.
- The findings suggest that “hybrid immunity,” resulting from vaccination and infection, involves the strongest immune response. Some call it “super immunity.”
- Overall, the order of vaccination and infection made little difference to the attainment of this immunity.
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With so many people, including fully vaccinated individuals, contracting SARS-CoV-2, researchers want to understand how the combination of vaccination and the infection might influence the immune response.
A new study from Oregon Health and Science University (OHSU), which appears in Science Immunology, explores this issue.
It also investigates the antibody response of people who were unvaccinated at the time of the infection but later became vaccinated.
Since COVID-19 was first detected in late 2019, more than 360 million people have contracted SARS-CoV-2, and almost 5.6 million people have died, globally.
To combat the pandemic, medical teams have administered an incredible 9.6 billion doses of COVID-19 vaccines so far.
As expected, as rates of vaccination increase, healthcare professionals register more breakthrough infections. This type of infection involves a fully vaccinated person contracting SARS-CoV-2.
Compared with unvaccinated people, vaccinated individuals are less likely to develop severe illness or die from COVID-19, the Centers for Disease Control and Prevention (CDC) report.
“The likelihood of getting breakthrough infections is high because there is so much virus around us right now,” explains Dr. Fikadu Tafesse, co-senior author of the study and an assistant professor of molecular microbiology and immunology at OHSU.
Scientists know that SARS-CoV-2 infection provides a degree of natural immunity, but there is much debate about how long this immunity lasts and how effective it is, compared with the immunity that vaccination provides.
Given the current high rates of breakthrough infections, and given that some people are getting vaccinated after having contracted the virus, researchers are curious about how these factors affect the body’s immune response.
The authors of the recent study gathered data from 104 participants, whom they divided into three categories:
- fully vaccinated people with a breakthrough SARS-CoV-2 infection
- people who had a SARS-CoV-2 infection followed by vaccination
- fully vaccinated people with no history of a SARS-CoV-2 infection
The first group had 31 participants, the second also had 31, and the third had 42 participants.
The scientists took blood samples from the participants and exposed them to different live SARS-CoV-2 viruses. They then measured the immune response.
The researchers determined that it did not matter whether someone received the vaccine first or contracted the infection first. The immune system responded similarly.
“It makes no difference whether you get infected and then vaccinated or if you get vaccinated and then a breakthrough infection,” says Dr. Tafesse. “In either case, you will get a really, really robust immune response — amazingly high.”
The researchers also determined that the “hybrid” immune response is strong regardless of age, whereas the response from only the vaccine tends to decrease with age.
The team found that the hybrid immune response is strong, regardless of how people obtained this immunity. However, it is still best to get vaccinated first and take steps to prevent the infection.
“We position ourselves better by getting vaccinated,” Dr. Tafesse explains. “And if the virus comes, we’ll get a milder case and end up with this super immunity.”
“It’s the best immunity you can get, but I wouldn’t think of hybrid immunity as being a force field that can completely stop it, no matter what.”
The researchers believe that this so-called super immunity might signal that the COVID-19 pandemic will become endemic.
“These results, together with our previous work, point to a time when SARS-CoV-2 may become a mostly mild endemic infection, like a seasonal respiratory tract infection, instead of a worldwide pandemic,” says co-senior author Dr. Marcel Curlin.
Dr. Curlin is an associate professor of medicine at the OHSU School of Medicine and director of OHSU Occupational Health.
Dr. William Messer, a senior co-author of the paper, spoke with Medical News Today about the study. Dr. Messer is an assistant professor of molecular microbiology and immunology and medicine at OHSU.
“As for the shift toward ending the pandemic — I think this is a piece in the puzzle, even a pretty big piece, but there are many things to factor in, not least the ongoing evolution of the virus itself,” Dr. Messer explained.
Dr. Messer added that the researchers “hope to study this ‘super immunity’ effect for Omicron, specifically asking the question whether infection with Omicron has similar boosting properties.”
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