Antibodies 6 months after COVID-19 infection

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Patients undergoing renal dialysis show encouraging antibody levels 6 months after SARS-CoV-2 infection, with slow decreases thereafter, suggesting a good immune response to COVID-19 among these patients, which they present a high risk of serious results.

“Our study is the largest to describe the longitudinal humoral response in a population that reflects the groups most affected by SARS-CoV-2 infection,” writes Shuchi Anand, MD, of Stanford University, California, et al. · Leagues in one to study published May 18 in Annals of Internal Medicine.

“Almost all seroprevalent patients in our study had evidence of a detectable immunoglobulin (Ig) G response from the receptor-binding domain (RBD) during 6-month follow-up,” they report. “Most met our test criteria to get a high-level response.”

“We saw a slow, continuous decline in median antibody levels over time, but we found no indication that subgroups with impaired immunity had a shorter-term humoral response.”

Age, comorbidities, race did not attenuate the adaptive response

The study included 2215 patients from a national sample representing 1200 dialysis centers across the United States. All patients had shown evidence of SARS-CoV-2 infection in July 2020 or earlier. Using plasma samples from monthly routine laboratory work, the authors analyzed monthly RGD IgG levels up to 6 months.

They found that up to 93% (n = 2063) of patients had achieved or maintained a detectable antibody response by assay, with an IgG index value of 1 or higher.

For 60% of patients, the immune response was classified as high (IgG ≥ 10) and 76% of participants in this group had a sustained response that remained high.

Mean index antibody levels slowly decreased from July to December 2020 (Pg <.001); however, there were no significant differences in changing level patterns according to factors such as age, sex, race / ethnicity, or diabetes status.

“Although we saw an increase in the distribution of these responses, the trajectory of the response did not vary by demographic (e.g., older age) or clinical (e.g., diabetes) strata that could be expected to attenuate. the adaptive immune response, ”the authors report.

However, of the 137 patients who did not show a detectable response by trial, there were some differences; patients were more likely to be white and among the younger (18–44 years) or older (≥ 80 years) age groups. They were also less likely to have diabetes and hypoalbuminemia.

Immune response patterns are inconsistent

Data on antibody responses after COVID-19 to the general population are limited and studies to date have shown contradictory patterns, with some indicating stable antibody levels or plateaus and others showing a rapid decline.

The new findings suggest something among dialysis patients.

“Our analyzes confirm the persistence of antibodies among a large majority (> 90%) of people over 6 months of age, but we do not have solid evidence of a plateau in the IgG RBD response,” the authors write. “Rather, the response appears to show a slow and continuous global decline from the median.”

Previous studies that included people on dialysis they received grip i hepatitis B vaccines suggest that they have impaired humoral immunity compared to the general population; however, new findings suggest more encouraging responses after COVID-19 infection.

“In our characterization of their response to natural SARS-CoV-2 infection … we found no evidence of a shorter-lived humoral immune response compared to the general population,” the authors write.

And “we found no differences in the durability of the response between men and women and for other clinically significant strata,” they write.

Survivor bias?

Patients on dialysis hospitalized with COVID-19 are known to have a high mortality rate; therefore, those who formed the basis of this study — who survived the infection and continued dialysis for monthly assessments — may represent a healthier subset of patients, the authors note.

Although patients older than 80 years were more likely to have low or no antibodies, the authors note that, in general, the majority of those 80 years of age or older (204 of 227 patients) obtained a detectable response.

It is important to note, however, that the authors note that the role of the level and duration of antibody response in protection against SARS-CoV-2 reinfection is not yet clear.

“Antibody titers are just a marker of immunity, and even people with low-level or undetectable antibody response can mount a post-reinfection protective response that abrogates symptomatic disease,” they conclude.

The study received funding from Ascend Clinical Laboratories.

Ann Intern Med. Published online May 18, 2021. Full text

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