It's being dubbed 'superhuman immunity'.
New research shows some people may have a significantly higher level of immunity to COVID-19 that could even protect them from future pandemics.
Scientists studied individuals who have recovered from the virus and then later received a mRNA vaccine, such as Pfizer or Moderna.
What they found was that protection against the disease and its variants was higher than immunity conferred by either infection alone or vaccine alone.
Paul Bieniasz is a virologist at the Rockefeller University, he prefers the term hybrid, rather than superhuman immunity:
"So this is a phenomenon that we and others have uncovered in people who were infected by SARS-CoV-2 early in the pandemic, and then some months later when vaccines became available, they were vaccinated."
"..Their antibodies were not only capable of neutralizing all of the SARS-CoV-2 variants that we have seen thus far, they're also capable of neutralizing viruses that are very much more diverse, including the original SARS coronavirus, which is really quite different to the current ones, viruses that are currently circulating in bats and pangolins..."
Bieniasz went on to urge caution, stressing that the research is new and needs more real world testing.
He said it did offer hope, though, for the people who had recovered from the disease and been vaccinated.
His team is investigating whether a third booster shot has the same effect.
So far, more than 226 million people around the world have been infected with COVID and some 4.8 million people have died.
The World Health Organization has said another influenza pandemic is inevitable - that it is a matter of when, not if.