Do you need a COVID-19 antibody test? Utah medical experts say no

More Utahns are expressing interest in being tested for COVID-19 antibodies, but healthcare experts, including federal officials, advise against using the tests to determine their protection against the deadly virus.

“Immunity is incredibly complex. Unfortunately, people want a simple yes / no answer. And as with most things, the real answer is, ‘It depends’, ”said Han Kim, professor of public health at Westminster College in Salt Lake City, adding that“ the risk of misinterpretation is too high ”with antibody tests.

Antibodies are only one aspect of the immune response, and it is not yet clear what levels are needed to fight future illnesses, Kim said. This makes it “difficult to predict whether you are immune to COVID in the future based on these tests, and that’s ultimately what people want to know.”

So, he said, there is no reason to seek the test “unless you want to donate the money.”

The United States Food and Drug Administration issued a “safety communication” in May stating that the results of “antibody tests should at no time be used to assess immunity or protection against COVID-19. , and especially after the person has received a COVID-19 vaccine. . “

A positive result from antibody tests – proteins made by the immune system to fight infections – does not mean someone is immune to COVID-19, according to the FDA, warning that interpreting the results in this way could cause people to take fewer precautions even though they may still be infected and spread the virus.

But that hasn’t stopped the Utahns from asking their doctors about the blood test, especially as the highly contagious delta variant of the virus is leading to an increase in cases across the country, including cases of major infections in those who are vaccinated that raise questions about booster shots.

“Absolutely,” there is increased patient interest in antibody testing, said Dr. Brandon Webb, infectious disease physician at Intermountain Healthcare. “Not surprisingly, healthcare providers find themselves discussing the benefits and limitations of antibody testing much more frequently. “

Webb said he thought it was because “it is a priority for the public to know” how protected he is from COVID-19, whether he has had the virus before or is vaccinated . But he said the tests “might actually create a false sense of security.”

The accuracy of tests for COVID-19 antibodies varies widely, Webb said, and there is no agreement yet on which is the most reliable and even what the results mean, so “in general, the antibody tests are still not recommended ”.

He said, for example, that a person who caught the virus earlier, when a different strain was circulating, could test positive for antibodies “which is great, but that doesn’t necessarily mean the individual is. fully protected against the delta variant. It depends entirely on the person’s health, age, immune status, and other factors.

Dr Julio Delgado, executive vice president of ARUP Laboratories, said antibody tests, including those at the nonprofit University of Utah, are being used to identify outbreaks, recovering plasma donors and illness in children and others who have never been tested for COVID-19 but deal with long-term effects.

Jeffrey D. Allred, Deseret News

Antibody tests have been used to study whether a person who is immunocompromised due to an organ transplant, cancer treatment, or other medical condition is getting an extra dose of the COVID-19 vaccine, said Delgado

For most Utahns, Delgado said, he sees “no rational or logical reason backed by science now that people would go alone and try to get tested for antibodies, or worse yet, try to get one of those over-the-counter tests, because they’re even more inaccurate. ”

What he called the curiosity surrounding antibody testing may be the result of a groundbreaking new case study in Israel showing a correlation between those who were infected and low levels of antibodies, suggesting that the delta variant is occurring. replied so quickly, for some there was no time for the vaccine to take effect.

The results are “a bit disturbing” and are already starting to be discussed on social media, Delgado said. “I anticipate that there is going to be a lot of interest. … People will start to say, ‘Wait a second. I want to know how many antibodies I have now that we’re surrounded by delta. ‘ “

In the last week alone, he said, he has heard from colleagues at the University of Utah Health who are receiving requests from their healthy patients who want to know their antibody level. Delgado said his response is that there is no threshold yet for what that level should be.

This could come as drug companies try to advocate for booster shots, he said. Pfizer, maker of a two-dose vaccine, has announced that it will seek emergency FDA approval to provide a third dose as additional protection against the delta variant.

Webb said issues with antibody testing were at the center of the booster injection debate.

“That’s what the FDA is working on right now, is how to make those recommendations when the tests and test results and levels aren’t standardized,” he said. “So tying these recommendations to a certain type of antibody test level requires that the tests themselves be more standardized and the interpretation of the results a little more concrete.”

For now, patients who want an antibody test are being told “we wouldn’t necessarily know what to do with the results,” said Webb, instead offering specific advice for those at higher risk of contracting. COVID-19 due to their age or state of health. condition, vaccinated or not.

“Rather than having their antibody levels checked,” he said, “I think the most practical and effective advice is for them to simply double the precautions they take while the delta variant increase – limit gatherings, wear masks indoors and distance themselves if possible. ”