Does a COVID-19 breakthrough infection actually give you 'super immunity'?

As the COVID-19 pandemic evolves, so does the world’s understanding of how the virus behaves. A recent study published in the Journal of the American Medical Association suggests that someone who has survived a breakthrough infection – meaning they caught COVID-19 after receiving two doses of the vaccine – may have obtained a “super immunity” against the virus.

According to researchers, the antibodies produced in those infected with COVID-19 after vaccination were up to 1,000 per cent more effective in protecting against severe disease, compared with vaccinated people who were not infected with the virus.

Dr. Lisa Barrett is an infectious disease specialist and professor at Dalhousie University in Halifax. In this situation, she said, an increased antibody response is expected.

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“That's how your immune system works,” she told CTVNews.ca in a phone interview on Thursday. “In people who have normal immune responses, it is completely expected that after your vaccines, if you get exposed to [COVID-19] and get what’s called a ‘breakthrough infection,’ you would see soaring antibody levels.”

This is part of the body’s response when it comes into contact with the virus, she said. But the concept of “super immunity” is one she’s still trying to understand.

“It's a great tagline but as an immunologist, I'm never quite sure what people are talking about,” she said.

Not only is “super immunity” not a valid medical or scientific term, it doesn’t really mean anything, said Dr. Dale Kalina, an infectious disease doctor at Joseph Brant Hospital in Burlington, Ont.

“You are either immune to something or you're not,” Kalina said in a phone interview with CTVNews.ca on Thursday. “In certain infections, you can measure or quantify the level of immunity that you would get…but that isn’t something we can do with COVID-19 right now.”

In situations where studies mention the term “super immunity,” said Barrett, they tend to refer to the development of high levels of antibodies that she described as “super binders,” meaning that they are effective at neutralizing the COVID-19 virus and preventing it from causing infection. The study in question points to “super immunity” that is obtained after a breakthrough infection.

But according to Barrett, many studies using the term are not yet linked to clinical trials involving actual patients.

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“In a test tube, it looks like…having high levels of antibodies should clinically work out well for you,” she said, referring to the potential for less risk of developing severe disease. “But that data is still evolving.”

While the probability of experiencing less severe disease and a reduced chance of death is higher among those who are fully vaccinated against COVID-19, said Barrett, she cautions against using the term “super immunity.” Higher levels of antibodies do not prevent a person from spreading the virus to others, she said, nor do they offer complete protection from infection.

“Super immunity implies to people that they're wearing armour – you're not wearing armour against all infection,” she said. “I worry the words ‘super immunity’ give people the superhero effect, and I caution against that because it's not true.”

HOW THE BODY RESPONDS TO COVID-19 VACCINES VS. INFECTION

The body’s reaction to vaccination is similar, in a sense, to how it responds when exposed to infection naturally, said Dr. Isaac Bogoch, an infectious disease expert and faculty member at the University of Toronto.

“Vaccination and infection do the same thing, in the sense that your body sees a virus, or at least a component of the virus from when people are vaccinated, and it mounts an immune response,” he told CTVNews.ca in a phone interview on Thursday.

This, however, does not mean they both produce the same end result, Bogoch said. A recent study published in the peer-reviewed medical journal Clinical Infectious Diseases looks at the necessity of COVID-19 vaccination in those who have already been infected with the virus. Conducted in the United States, the study concludes that while both vaccination and prior infection provide “substantial protection” against COVID-19, vaccination in patients who were previously infected provides significant protection in the long run, specifically against symptomatic COVID-19.

“It’s fair to say that yes, you can’t ignore the protective benefits of both vaccination and of course recovery from infection,” Bogoch said. “It just looks like vaccines provide a more robust immune response.”

An additional study on the protection offered by COVID-19 vaccines was also recently released by the U.S. Centers for Disease Control and Prevention. Researchers examined infections in New York and California across the summer and fall of last year. While protection in those with no vaccinations and infection was high, they discovered that people who were both vaccinated and survived prior COVID-19 infection had the highest level of protection against the virus.

“Vaccination remains the safest strategy for averting future SARS-CoV-2 infections, hospitalizations, long-term sequelae, and death,” reads the study.

The CDC however, did note several caveats to the research, and data was collected prior to the circulation of Omicron in the U.S.

DOES THIS IMPACT ON IMMUNITY CHANGE WITH OMICRON?

With the new variant’s seemingly enhanced ability to evade immunity from prior infection and vaccines, maximizing the number of antibodies produced by the body is necessary to overcome that, Barrett said. The best way to accomplish this is by continuing to get vaccinated, she said. Although current vaccines are better designed to protect against the spike protein of previous variants, Barrett said, they still offer significant protection against severe illness and death from Omicron.

“There's enough overlap [with current vaccines] that there's still a good effort of those antibodies to cut down on the virus and how it can divide and replicate in a person,” Barrett said. “But if you have higher levels of those really good antibodies, like you do after a booster [shot], then it is useful in protecting against Omicron in terms of bad disease and outcomes.”

For anyone tempted to let nature run its course and opt for natural infection as a means of boosting immunity, Kalina pointed to the fact that much remains unknown about the long-term consequences of COVID-19. Not to mention the possibility that the virus could result in death, he said.

“There are unintended negative consequences that could befall you, which would be awful, and that's regardless of whether you've had zero doses of a vaccine, or two or three,” he said. “It's always better to avoid a preventable illness.”

Whether someone has been previously infected with COVID-19 or not, all three experts recommend getting vaccinated with three doses of the COVID-19 vaccine for the best level of protection against the virus.

“Against Omicron, you've got 3.5-star antibodies that might keep you from dying or going to hospital but they're not really going to protect you as much from infection and feeling terrible,” she said of those with two doses of the vaccine. “Basically, if you want five-star protection…you’ve got to get the booster.”