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AdminMar 18, 20213 min read

Research spotlight: Using RWD to evaluate risk of COVID-19 reinfection

To date, approximately 66 million patients have recovered from COVID-19, globally. As the virus continues to be transmitted and patients with evidence of infection are re-exposed, there is a pressing need to understand the level of protection, if any, that is offered from humoral antibody response. 

According to one COVID-19 reinfection tracker, there have been 65 confirmed reinfections worldwide, with 11 confirmed cases in the U.S. While COVID-19 reinfection is thought to be rare, more research is needed to further build upon existing evidence and to quantify the risk of reinfection across a representative population. Real-world data (RWD) offers the opportunity to study reinfection in large, generalizable populations in near-real time. 

A recent study published in the Journal of the American Medical Association (JAMA) Internal Medicine used RWD to explore the risk of reinfection among patients with evidence of COVID-19 antibodies. The study was a collaborative effort across a team of researchers from the National Cancer Institute (NCI), Aetion, HealthVerity, Quest Diagnostics, and LabCorp. 

Read on to learn more about the study, and what real-world evidence (RWE) reveals about COVID-19 reinfection. 

Goal of the study
Our research team aimed to understand whether RWD could be used to evaluate the comparative risk of COVID-19 infection among individuals who were previously infected, versus those without prior infection. If so, our team would further evaluate the risk of reinfection in time intervals spanning 0-30 days, 31-60 days, 61-90 days, and beyond 90 days post-index. 

Process for the analysis
We used health insurance data from HealthVerity’s Marketplace of de-identified commercial laboratory tests and medical and pharmacy claims. We created cohorts on the Aetion Evidence Platform® that categorized patients as antibody positive or negative based on their first COVID-19 antibody test in the data set. The cohorts captured approximately 3.2 million patients in the United States, of which 11.6 percent were classified as positive for COVID-19 and 88.3 percent were classified as negative. 

We then explored these individuals’ demographics, comorbidities, and COVID-19 signs and symptoms, as well as their follow-up testing patterns. We relied on a positive diagnostic nucleic acid amplification test (NAAT) during follow-up to determine potential infection or reinfection cases for those patients indexed as negative or positive, respectively. 

Key findings from the research
Patients with positive antibody test results were initially more likely to have positive NAAT results, consistent with prolonged RNA shedding, but became less likely to have positive NAAT results over time. Among our cohort of approximately 3.2 million patients, we found that of those who indexed with a positive antibody test result, 0.3 percent had evidence of a positive NAAT beyond 90 days post-index, compared with 3.0 percent of those who indexed with a negative antibody test result. This reduction in risk for antibody positive individuals indicates that being antibody positive is associated with partial protection against a subsequent infection. 

Implications on COVID-19 understanding and research
The results of this study suggest that individuals who are antibody positive for COVID-19, based on commercial assays, may be at a decreased risk of future COVID-19 infection. This is encouraging evidence that achieving herd immunity may be possible, especially in conjunction with vaccine deployment. Additionally, these results lay the groundwork for future RWE studies to leverage a representative population in near-real time to estimate the relative risk of COVID-19 reinfection, understand how that risk may change over time, and identify populations that may be more at risk for reinfection.