I still don't have Covid. Does science know if I'm really immune?

More than four years have passed since the beginning of the COVID-19 pandemic, and during that time nearly everyone in the US has been exposed to the SARS-CoV-2 virus.  Still, there remains a subgroup of people who have never been sick or tested positive.

More than four years have passed since the beginning of the COVID-19 pandemic, and during that time nearly everyone in the US has been exposed to the SARS-CoV-2 virus. Still, there remains a subgroup of people who have never been sick or tested positive.

Lee Suzuki/The Chronicle

More than four years have passed since the beginning of the COVID-19 pandemic, and during that time nearly everyone in the US has been exposed to the SARS-CoV-2 virus. Still, there remains a subgroup of people who have never gotten sick or tested positive, including me.

Experts say it is not easy to know how many of these people are true “novids” or super-dozers, because some may have had corona without knowing it.

Some people may have had coronavirus but had no symptoms, or had mild symptoms, leading them to think it was caused by some other disease. Others may have cleared the virus before symptoms were detected, got tested at the wrong time, the home test did not pick up enough viral particles to record a positive result, or blew their nose incorrectly. .

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But the possibility remains that some people have never actually been infected.

In a Gallup poll earlier this year, 59% of adults said they have tested positive for COVID, while 11% have not tested positive but believe they have had the infection.

John Swartzberg, emeritus clinical professor of infectious diseases and vaccinology at UC Berkeley, said some surveys suggest the percentage of those infected may be as high as 75%.

SAN FRANCISCO, CALIFORNIA - APRIL 30: Pedestrians walk along the Embarcadero on April 30, 2024 in San Francisco, California.  California's population is expected to grow in 2023 for the first time since the COVID-19 pandemic.  The state saw an increase of 67,000 new residents bringing the total number of people living in California to more than 39 million.
Dr. Delkha Shaheen examines a 34-year-old, unvaccinated, COVID-19 patient at Providence Cedars-Sinai Tarzana Medical Center in Tarzana, California, on September 2, 2021.  - According to Dr. Yadegar in the hospital, the number of Covid patients is much less than in winter, but from a psychological point of view it is much more difficult because most of the patients living on respirators in the ICU are unvaccinated, young and healthy 30 and There are people in their 40s with no co-morbidities.  Patients receiving the vaccine in hospital are generally older, but those who have more severe symptoms are less likely to be affected by Covid-19.  (Photo by Apu Gomes/AFP)

“This would not be surprising, given how contagious this virus is,” he said. “And many people have been infected with the virus but never developed symptoms or thought they just had allergies or a mild cold.”

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A year ago I wrote a story about COVID holdouts in which experts shared some theories as to why some people might have survived the virus, including “vaccination status, masking, the type of variant spreading, lifestyle Options that reduce overall risk – and just plain luck.”

So at this stage, are these possible causes still valid?

Dr. Dean Winslow, professor of medicine at Stanford University, believes these things are “still largely true.”

He said that while most people have recovered from the pandemic, others are still taking at least some precautions. For example, he said, some older infectious disease doctors like himself (he's 71) may still be uncomfortable going into crowded, indoor public spaces. And other older people, those who have weakened immune systems or have certain medical conditions, may still be taking steps like masking up.

So what does it mean to be a COVID holdout at this time as new subvariants threaten a potential heat wave?

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Swartzberg said the new FLiRT subvariant, which is now the dominant strain, “is likely to be more infectious than all previous variants.”

“Some researchers predict we will see a surge in cases sometime in June or July,” he said. “The most accurate thing I can say is that my crystal ball is pretty blurry right now.”

That means COVID holdouts may ultimately be at greater risk of contracting the disease, especially as vaccine immunity from last fall has waned.

But Chin-Hong struck an optimistic tone that if you've never had COVID before, it's better to catch it now than in past years. “For a small percentage of people who have never actually been infected,” he said, “many people will have had multiple vaccinations by now, increasing their immune protection with different versions of the vaccines over time. “

Additionally, he said, there are more tools available, including antivirals and monoclonal antibodies, to help keep people from being hospitalized if infected.

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“This means that people can potentially live their normal pre-pandemic lives without shutting themselves down at home, even if they are at high risk, as long as they stay up to date on vaccines and know that early antiviral How to access therapy,” he said. , “I would much rather be a Novid now than in the early years of the pandemic.”

Vaccine technology also continues to improve, Swartzberg said. Notably, “we are on the verge of developing vaccines that will prevent infection, provide long-lasting immunity, and generate immunity to all current and future variants of SARS CoV-2,” he said.

Meanwhile, experts say the question remains unanswered about whether some people have naturally occurring immunity to the virus.

If they do, “it will likely be due to genetic variations of the receptor site that the virus uses to enter our cells,” Swartzberg said. “Probably the number of people is low considering how many people have been infected around the world.”

Research groups around the world are still trying to figure it out, but no new information has been found, Chin-Hong said.

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“Many people who thought they were immune actually got the disease,” he said.

According to Chin-Hong, a recent study found that it is possible that genetic factors make some people less likely to get infected. A mutation in the human leukocyte antigen (HLA), called HLA-B*15:01, may be present in about 10% of the population.

He said HLA is “like Batman's bat signal, and people with this mutation are likely to have a stronger signal” that allows immune cells to recognize infected cells more quickly and catch the enemy before symptoms appear. Is.”

The mutation probably doesn't prevent infection, he said, but when someone with it gets COVID, they may be asymptomatic. The study showed that 20% of people who were asymptomatic after infection had one copy of the mutation, and 9% of those with the mutation had symptoms.

“People who had two copies of the mutation were 8 times less likely to have symptoms when infected than people who did not have two copies of the mutation,” Chin-Hong said.

Chronicle reporter Edin Vaziri contributed to this report.

Reach Kelly Hwang: [email protected]; Twitter: @KellieHwang

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