Infectious Disease

Antibodies seem to supply safety in opposition to re-COVID-19 an infection

February 24, 2021

2 min read

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Disclosure:
Harvey reports being an employee of Aetion, Inc who received payment for services for the work submitted. Katz does not report any relevant financial information. In the study you will find all relevant financial information from all other authors.

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Patients with COVID-19 antibodies appear to be protected from re-infection for at least a few months, according to a study published by JAMA Internal Medicine.

In the study, researchers observed lower rates of positive nucleic acid amplification tests (NAATs) in patients who previously tested positive for COVID-19 antibodies than in patients who tested negative.

“The data from this study suggest that people who get a positive result in a commercial antibody test appear to have significant immunity to SARS-CoV-2, which means they may have a lower risk of future infections.” Lynne Penberthy, MD, MPH, The National Cancer Institute’s assistant director of the surveillance research program who led the study said in a press release. “Additional research is needed to understand how long this protection lasts, who may have limited protection, and how patient characteristics such as comorbid conditions can affect protection. We are nevertheless encouraged by this early realization. “

Penberthy and colleagues conducted a retrospective descriptive observational cohort study that used unidentified data from commercial laboratory tests, medical and pharmacy claims, EHRs, and hospital billing accounts. The researchers examined patient records from December 2018 to August 28, 2020 to identify patients who received SARS-CoV-2 antibody tests from January 2020 through the end of the study period.

Patients were categorized based on the time of their first SARS-CoV-2 antibody test result. They were followed up until the end of the investigation period. During this time, the researchers identified additional antibody tests, or NAATs.

The researchers found that a positive NAAT result within 30 days of a positive SARS-CoV-2 antibody test is likely caused by virus shedding. However, since most virus shedding is expected to end after 90 days, positive NAAT results during this period may indicate a new infection.

The researchers identified 3,257,478 patients who took an antibody test. Among them, 88.3% had initially negative index antibody results, 11.6% had initially positive index antibody results, and 0.1% had inconclusive antibody test results. Of the patients with positive antibody test results, 18.4% became seronegative during the follow-up period.

In patients with initially positive antibody results, 11.3% had positive diagnostic NAAT results within 30 days of their antibody test. This percentage fell to 2.7% after 31 to 60 days of the antibody test, to 1.1% after 61 to 90 days, and to 0.3% more than 90 days after the antibody test.

Of those patients who initially had negative antibody results, 3.9% had positive NAAT results within 30 days. According to Penberthy and colleagues, the proportion of patients who initially tested negative for SARS-CoV-2 antibodies and later tested positive with an NAAT was approximately 3% during the entire follow-up period, even after 90 days.

Penberthy and colleagues found that when compared to those who initially tested negative for antibodies, the ratio of positive NAAT results to those who had positive antibody test results was 2.85 (95% CI, 2.73-2, 97) after 0 to 30 days to 0.67 (95% CI, 0.6-0.74) after 31 to 60 days, 0.29 (95% CI, 0.24-0.35) after 61 to 90 Days and 0.10 (95% CI, 0.05-0.19) after more than 90 days of the first test.

In an editor’s note published alongside the study Mitchell H. Katz, MD, wrote that the results are consistent with previous research by health care workers who have received antibody tests, but these studies cannot determine how long antibody protection will last from a natural infection. For this reason, a COVID-19 vaccination is recommended regardless of whether a person has antibodies.

“How long the antibody protection offered by vaccines lasts is also unknown,” wrote Katz. “Knowing how long the protection with antibodies lasts from a natural infection or vaccination will only tell time.”

References:

Harvey RA et al. JAMA Intern Med. 2021; doi: 10.1001 / jamainternmed.2021.0366.
Katz M et al. JAMA Int Med. 2021; doi: 10.1001 / jamainternmed.2021.0374.

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