LOS ANGELES (KGO) -- For nine months doctors at Cedar Sinai Medical center in Los Angeles checked the coronavirus antibody levels of nearly 2,500 people. What they found shocked them.
"Their antibody levels went up signaling that in fact around some early time period their immune system had seen the actual virus enough to actual mount a response. Developed antibodies to the actual core part of the virus indicating they actually were infected at that time. They just didn't know it," said Dr. Susan Cheng, Director of the Institute for Research on Healthy Aging at Cedars-Sinai Medical Center in Los Angeles.
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Dr. Cheng is one of the doctors behind the study. Blood samples confirmed that during the omicron surge only 44 percent of people who were part of the study knew they were infected with COVID and 56 percent had no idea they had antibodies.
"We started to see that second antibody level actually really start to go up in a lot more people. That was the omicron surge. We started to see the antibody that really goes up as a sign that your immune system has seen the natural virus that really started to take off across many of our study participants during that late December, late January, February period," said Dr. Cheng.
Your level of natural immunity could also be correlated to the level of infection you were exposed to. Dr. Chaz Langelier, Infectious diseases scientist at UCSF & Chan Zuckerberg's BioHub explains why time is important to detect these antibodies.
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"Most people will still be antibody positive after three months. Most after six months but after that point you know there is more variability," said Dr. Langelier.
During this study the 56 percent of people who were unaware of their natural immunity hadn't gotten tested for COVID. These findings highlight the importance of testing and not just checking for symptoms.
"It really means that screening people based on symptoms alone is insufficient," said Dr. Langelier and added, "Like hospitals and clinics you can't just ask someone if they have any cold or flu symptoms or have a fever because half of people could still be infectious," said Dr. Langelier.
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Why is it that some people develop symptoms and others don't?
"Probably as all things it's a combination of genetics. It's a combination of pre-pandemic exposures. There is a theory out there and I think it's a valid one. People who have been exposed to similar types of other forms of coronavirus may have developed some forms of immunity that have really protected them," said Dr. Cheng.
Dr. Cheng also believes that in some cases building natural antibodies could be related to people's immune system and how that makes them more resistant to developing or being infected at all.
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