PORTSMOUTH — COVID-19 has been pervasive for more than two years. It has been almost impossible to evade. Yet there are those who claim to have never contracted the virus that laid low the world.
Is it possible that some people may be immune to the virus? Do they have super-immunity?
Possible, but unlikely, say the infectious disease experts. Because of that, they continue to urge those who think they are immune, and everyone else, to take precautions.
Dr. Vandara Madhavan, clinical director of pediatric infectious disease at Mass General for Children, said there are two different mechanisms, leading to thoughts on why some people seem to not get COVID-19 even after repeated close contact with infected people, even family members they live with.
"First is that they have had a true infection that has not been detected," she said. "Initially, when the pandemic began, testing was difficult to access. So we did things like test a parent and then, if positive, assume the entire family was infected. Now tests are easier to get and people can even test at home."
What access to better testing showed is variants, like delta and omicron, while highly transmissible, produced milder cases in most vaccinated people.
"So people might not be among those counted, because they are not sick, or they are so mildly sick they chalk it up to a cold or to allergies," Madhavan said. "Even so, they are developing antibodies, even in the large part of the population who have had COVID and didn't know it because they did not develop enough of a viral load for it to be detected on a home test."
The second thought, said Madhavan, is that in certain people an intrinsic part of their being is capable of acting naturally to repel the virus. She said it is speculation at this point, but it is certainly possible.
"For whatever reason, and we do not know what that is at this point, these people are not getting infected, possibly because their immune system is already revved up by a different infection they cleared," she said. "Is it possible they already have a history of some respiratory infection and they might be experiencing cross protection? Possible."
Dr. David Itkin, a Seacoast area infectious disease expert, said having certain people appear to be immune to a particular virus is not new.
"It's a huge circumstance of how a virus will express itself," Itkin said. "Say there is a family of five, all exposed to an entero virus, which causes a summer flu-like illness. This is highly contagious, yet the odds are good that two people will experience a rash and fever, one could be diagnosed with viral meningitis and the remaining two might show absolutely no symptoms."
Various ways you may develop immunity to a virus
Itkin said in his scenario, the two people probably have developed pre-existing immunity from a previous infection, so they are now relatively resistant to the new exposure.
The same thing might be happening with COVID-19. Itkin said there is a chance that for some, having cleared other respiratory illnesses offered a level of immunity, a sort of long induced memory of clearing infection.
Itkin said some believe they are immune because they had a previous exposure unmarked by them because it was such a mild case. That might be because they are vaccinated and boosted, adding to their resistance.
"Or, it is just the luck of the draw," he said. "Two siblings living practically on top of each other will share the infection and another in the household who works long hours can escape infection.
Itkin said COVID-19 is a complex virus and about 40% of the population have been non-symptomatic.
"Still, there may a genetic factor in some person's immunity," he said. "We just do not know yet. There is a gene, the OAS gene, that is being studied which may decrease expression of the immune response, resulting in higher hospitalizations. Is there some way this gene can be exploited? It remains to be seen."
Madhavan said there is still so much investigation as to whether a genetic variant could make people "super-immune."
Definitely the question of super-immunity is a "big shrug of the shoulders," Madhavan said, because there is no answer and people need to remain vigilant.
Need to remain vigilant, practice precautions
"Wear the mask," she said. "Be wary of large crowds. We have learned much in these couple of years. I think there is a lot more to be learned. We still do not know the far-reaching ramifications of long COVID. Does the virus stay in your system, like the chicken pox virus which can cause shingles later in life. We simply do not know, so continue to take the necessary precautions to avoid the virus."
Itkin said he is not ready yet to say a person can be immune to the COVID-19 virus.
"I'd be more likely to go out on a limb and say the people who think they are immune have been exposed and have successfully fought off a mild case," he said. "Stay on guard and do not think you are superman because we don't know. Get all the vaccinations recommended because that timing could keep your antibodies stronger when you are exposed. Assume you are susceptible because you probably are."
This article originally appeared on Fosters Daily Democrat: Can you be 'super-immune' to COVID-19? Here's what doctors say.