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Two recent, non-peer-reviewed studies indicate that people who have recovered from COVID-19 may have a superior level of immunity when compared to vaccines alone. Getty Images/Corinna Kern
  • According to two recent, non-peer-reviewed studies, people who recovered from COVID-19 produced a robust immune response that was superior to vaccination alone, and adding one or more vaccine doses offered even stronger protection.
  • Fully vaccinated people who recovered from a rare breakthrough case also showed a higher level of immunity than people who were only vaccinated.
  • Researchers stress that vaccines alone continue to provide excellent protection against severe COVID-19 symptoms.

New research from the United Kingdom found that people who have had COVID-19 and also received both doses of the vaccine had higher levels of antibodies compared to people who had only acquired the virus or had only been vaccinated.

The study, which was published on the pre-print server medRxiv on August 24 and not yet peer-reviewed, evaluated the effectiveness of the Pfizer, Moderna, and AstraZeneca (which is not available in the United States) vaccines against the Delta variant and found that while vaccination still provides significant protection, fully vaccinated people who previously had COVID-19 are the best-protected group.

Another pre-print posted in medRxiv on August 25, which looked at only the Pfizer vaccine, found that protection against the Delta variant from a prior case appears to be stronger than the immunity conferred from vaccination.

Neither of the studies included the one-dose Johnson & Johnson COVID-19 vaccine.

The report, which is the largest real-world observational study comparing natural immunity to vaccine-induced immunity, found that people who previously had COVID-19 were less likely to acquire the Delta variant, develop the symptomatic disease, or require hospitalization compared to vaccinated people who had not previously had the disease.

People with prior COVID-19 disease who received at least one dose of the vaccine had even stronger and longer-lasting protection against the Delta variant, according to the findings.

Based on these preliminary studies, acquiring the virus confers durable, lasting protection, which can be further strengthened by vaccination.

While vaccinated individuals who’ve previously had COVID-19 can feel very safe, it’s important to recognize that the strength of everyone’s immune systems is different.

Your chances of redeveloping the disease depend on your genetics, health, how you were exposed, and what variant you were exposed to.

People who previously acquired SARS-CoV-2 who subsequently got fully vaccinated are well protected against COVID-19.

“When you’re infected, you develop big-time immunity toward one variant,” says Dr. Robert G. Lahita, the director of the Institute for Autoimmune and Rheumatic Disease at Saint Joseph Health and author of “Immunity Strong.”

The vaccine is then given to boost that immune response, strengthening their protection.

“You have to remember the vaccines were shown to be effective at preventing severe disease, hospitalization, and death,” says Dr. Albert Rizzo, the chief medical officer with the American Lung Association.

Growing evidence suggests that immunity conferred from previous cases may be even more robust than the protection gained from vaccination.

According to Rizzo, it’s important to realize that if they’re in an area where Delta is surging, and if they’re in a high-risk environment, people who previously acquired the virus and vaccinated individuals could still get the virus again.

“But, in the back of their mind, they should remember that they are hopefully very protected against severe illness, even though they may get infected,” Rizzo said.

Everyone’s immune response will vary based on their genetics, how they were exposed to the virus, and which variant they will respond to.

“All that plays a role in deciding what neutralizing antibodies get developed by the individual,” Rizzo said.

There’s also the question of how long those antibodies remain viable and effective, which remains unclear.

“Everybody’s immunogenetics are different,” says Lahita. Some people have a robust immune system, while others have weaker defenses.

In fully the vaccinated or those who’ve had the coronavirus, certain COVID-19 variants, like Delta, may not be as quickly recognized by a person’s existing antibodies, which can lead to milder breakthrough infections.

Fortunately, in addition to antibodies, the immunity conferred from both natural cases and vaccination includes T cells and memory B cells.

Memory B cells and T cells stay in the body longer, often for years, and are effective at preventing a case from becoming severe or life threatening.

Fully vaccinated people who have recovered from a recent breakthrough illness may have the highest level of protection.

After acquiring Delta, recovered individuals will have protective antibodies specific to the variant.

Still, people should assess their personal risk when determining what activities they feel comfortable doing.

“Remember, everybody — because of immunogenetics — is going to produce a different titer, they’re going to produce a different strength of the neutralizing antibodies. Not everybody is going to have the neutralizing antibody in big strengths,” Lahita said.

People who have a lot of comorbidities, are older, immunocompromised, or are on cancer therapies will still need to gauge their personal risk tolerance in areas with high transmission, says Rizzo.

As long as COVID-19 is prevalent in our communities, we can’t make the risk zero.

According to Rizzo, all we can do is mitigate the risk, and mitigating the risk goes a long way with vaccines, wearing a mask in high-risk environments, and isolating at home if you develop symptoms.

New research has found that people who have had COVID-19 and also received both doses of the Pfizer, Moderna, or AstraZeneca vaccines had higher levels of antibodies than people who had only acquired the virus or only been vaccinated. The one-dose Johnson & Johnson vaccine was not included in this research.

Acquiring the virus confers durable, lasting protection against reacquiring it, which can be further strengthened by vaccination.

Still, because the durability and versatility of antibodies is unclear, a small portion of previously cases or vaccinated people may still experience breakthrough illness. However, since these people will have some level of baseline immunity, these breakthrough cases are significantly less likely to become severe or life threatening.