What happens if I have COVID-19 antibodies? Here’s what health officials say you should know, and why you should still get vaccinated

What antibodies are, and why health officials recommend you should still get the COVID-19 vaccine

DeKALB – For those wondering what they should do if their COVID-19 antibody test results come back positive, and what that might mean for vaccine plans, one area health official has some answers for them.

For starters, an antibody test is different than a COVID-19 tests, said Dr. Bob Manam, medical director of infection prevention at Northwestern Medicine Kishwaukee Hospital in DeKalb,

He said the typical nasal swab test normally used for those seeking confirmation as to whether they contracted COVID-19 currently looks for antigens, or current infection from the virus.

“We can see that the virus is present,” Manam said.

What are COVID-19 antibodies?

The antibody test, however, is a blood test. And it determines whether someone had the illness previously, Manam said. When someone has a blood test, they can choose to also get it tested for COVID-19 antibodies, meaning a protein in the blood called immunoglobulin would exist positive. When a person is exposed to the COVID-19 virus, their body’s immune system will as a result begin to produce immunoglobulin to fight off the virus. So presence of the immunoglobulin antibody would confirm that person may have already contracted or been exposed to COVID-19.

“Which would mean the person has been exposed sometime in the past to COVID and is already immune to COVID,” Manam said.

Manam said an antibody test might be ordered for someone who had COVID-19-like illness but their nasal swab test came out negative, though a doctor still strongly suspects it’s COVID-19. However, he said, the test isn’t typically used for diagnosis or treatment.

“Do we use it often? Not too much,” Manam said.

If I have antibodies do I still need to get vaccinated?

Yes, Manam said, as long as a patient is feeling well, doctors still recommend people get the vaccine even if they previously contracted COVID-19 or tested positive for virus antibodies.

He said the body’s response in developing antibodies through the vaccine is more ‘reproducible,’ meaning it would provide a higher level of immunity. Vaccines work by simulating the conditions of a viral infection without actually introducing any live virus into the system. As a result, the immune response is to create antibodies to help fortify against future infection, according to the Centers for Disease Control.

If you’ve had the virus before, doctors recommend getting vaccinated still because it’s not yet known how long immunity against possible future infection can last.

Manam said those who had a natural COVID-19 infection are theoretically more susceptible to getting the illness again and sooner.

“If you have a vaccine, it looks like it’ll be a very good antibody response for a year,” Manam said.

Will I test positive for COVID-19 after developing antibodies or getting fully vaccinated?

No, according to the CDC. However, you could result in a false positive antibody test.

According to the U.S. Food and Drug Administration, antibody tests may detect coronaviruses other than SARS-CoV-2, such as viruses that cause the common cold, and may result in false positive results. Although the agency has authorized the tests submitted for their review, false positives also can happen when testing is done in a population with not as many cases of COVID-19.

If someone has an autoimmune disease, Manam said, they could possibly test positive falsely for COVID-19 antibodies. He said it’s a similar phenomenon as patients testing positive for lime disease when they have lupus.

False positive results can be limited by patients getting an antibody test with high specificity – meaning it yields a high positive predictive value in populations tested with low prevalence of COVID-19 – done and having populations and people who are more likely to have had the illness tested, according to the Centers for Disease Control and Prevention. However, the agency also reports health officials don’t have enough information yet to say how protected someone might be from being infected again if they have those antibodies, though confirmed and suspected cases of reinfection are rare.

Additionally, it takes time to build immunity after receiving both vaccine doses, according to the CDC. The agency reports it typically takes a few weeks for the body to build immunity (protection against the virus that causes COVID-19) after vaccination. That means it’s possible a person could be infected with the virus just before or just after vaccination and still get sick, because the vaccine has not had enough time to provide protection.

How long does it take for immunity to build after I’ve been fully vaccinated?

The CDC reports natural antibodies usually start developing within one to three weeks of infection. However, health officials don’t yet have enough information yet to say how long those naturally-developed antibodies (from viral exposure of infection) last to ward off future reinfection.

For immunity following a second dose of COVID-19 vaccine, the CDC reports immunization will likely occur within one to two weeks

Manam said the amount of time it would take for the antibodies to form would be about the same amount of time those who are symptomatic would have to quarantine anyway.

“By the time the person has the antibody, it would be unlikely that they would be truly capable of infecting others,” Manam said.

Why developing antibody immunity matters

Manam said the improvement seen in the decline of COVID-19 cases and hospitalizations with the vaccine rolling out is really illustrated in nursing home data. He said there has been a steep drop in nursing home deaths related to COVID-19.

Manam said elderly residents at long term care facilities aren’t really able to protect themselves from the virus otherwise, despite all of the health precautions taken at those sites.

“It’s their home,” Manam said. “And with 80 people, it’s going to pass through very quickly.”

Do I still need to wear a mask after getting fully vaccinated?

Yes, health officials said. Manam said it’s still strongly recommended to wear face masks, meaning both the mouth and nose are covered by the mask.

“It could be considered our real first vaccine,” Manam said. “ … The mask will work if appropriately used.”

According to the CDC, researchers still don’t know whether someone who’s fully vaccinated can still pass the COVID-19 virus on to someone who’s, even if the vaccinated carrier doesn’t get sick themselves.

And with the slow vaccine rollout, mask-wearing is still being heavily emphasized.

For now, Manam said, there’s still a risk in spreading infection when gathering indoors unless everyone had the disease or is vaccinated.

“We’re definitely heading in the right direction, though.”

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