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Study: Herd immunity from COVID-19 may be closer than expected

A new study shows the number of COVID-19 infections in our country may actually be twice as high as the numbers we see from confirmed test results.

Edie Lambert, KCRA, Mar 25, 2021

At this point, that may be good news. It could be proof we may be getting closer than expected to herd immunity.

Researchers at the medical testing and treatment company Clinical Reference Laboratory looked at the blood samples taken from 61,910 people who had applied for life insurance. They tested for antibodies that indicate whether or not someone had recovered from the virus. They found twice the rate that would be expected if you just looked at the number of confirmed tests, and this held true for the numbers across the nation.

There are a lot of factors that would explain their results. At the beginning of the pandemic, tests were scarce and it was hard for people to get tested. As many as 40% of people with COVID-19 have no symptoms, according to the CDC. Some never even knew they had the virus. In a third category, many people with mild cases don't get tested if they don't need to go to the hospital.

UC Davis Health infectious disease expert Dr. Dean Blumberg was not surprised to see the results of the study and says there's now a lot of research backing up the same numbers.

When you combine the number of people with this natural immunity, with the rising number of people getting vaccinated, it means the pandemic could end sooner than expected. Dr. Blumberg explained, "We hope what that means is we can reach herd immunity sooner with lower rates of immunizations."

Herd immunity is reached when enough people become immune to a disease that it's much less likely to spread. Blumberg said experts aren't sure when that will happen with COVID-19 because it's a new disease, but they think between 60% and 80% of the population will need to become immune.

"So the more that are immune already as a baseline, that means that we can achieve that sooner with our vaccination campaigns," Blumberg said.

If you've already contracted the virus, you may be wondering whether you need to get vaccinated, or whether your natural antibodies are enough. According to Blumberg, those who have recovered do benefit from vaccinations, because it's hard to know how long the natural antibodies will last. The vaccine can actually provide a stronger immune response, but it varies case by case.

After being worried for a year about the number of people getting the virus, this study and others like it show there's a positive side: those who have recovered are now much less likely to spread it.

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