Studies offer insight on SARS-CoV-2 immunity among dialysis recipients

Despite having weakened immunity, patients who underwent dialysis sustained receptor-binding domain IgG antibody levels for at least 6 months following SARS-CoV-2 infection, according to data from a sample of U.S. dialysis facilities.

A second study from Canada showed that one dose of the Pfizer/BioNTech vaccine “failed to elicit a humoral immune response” in most dialysis recipients without prior SARS-CoV-2 infection, even after “prolonged observation.” This study also showed a delayed response in those with prior SARS-CoV-2 infection.

‘Truly a benchmark’

In the first study, Shuchi Anand, MD, MS, director of the Center for Tubulointerstitial Kidney Disease at Stanford University, and colleagues prospectively reviewed plasma from 2,215 dialysis recipients who tested positive for SARS-CoV-2 antibodies in July 2020 to assess the persistence of SARS-CoV-2 receptor-binding domain (RBD) IgG over 6 months.

“At the current moment, this type of work is truly a benchmark for assessing response to vaccination, to help clinicians decide, for example, relative to a person with natural infection, what is the protection their patient may have received post-vaccination,” Anand told Healio Primary Care.

Anand and colleagues reported in Annals of Internal Medicine that 93% of the patients had an assay detectable response (IgG index value 1) during the 6-month follow-up period. Of the 1,323 (60%) participants who had high index values (IgG 10) in July 2020, 76% continued to have high index values in December 2020.

Overall, the researchers noted a “slow and continual decline” in patients’ adjusted median index values, starting at 21 in July 2020 and reaching 13 in December 2020 (P < .001). A patient’s age, sex, race/ethnicity and diabetes status had no effect on the path of his or her response. Patients who did not reach an assay detectable response tended to be white, aged 18 to 44 years or aged 80 years and older and less likely to have diabetes and hypoalbuminemia.

Anand said the research team was “surprised to see that most patients maintained antibodies after natural infection.”

“One reason for our finding may be that although this population does have comorbidities, we are studying them after they have gone through a SARS‐CoV‐2 exposure and survived infection. So, their health status is better than the sickest patients receiving dialysis,” Anand said. “Another reason may be is that there are data to suggest that persons with symptomatic or severe infection have a more intense antibody response.”

The researchers are currently investigating dialysis recipients’ response to COVID-19 vaccination.

“We hope to see a measurable antibody response to SARS‐CoV‐2 in a majority of people on dialysis, which would imply that our population is at lower risk for death or other complications from COVID-19,” Anand said. “This would be a fantastic public health achievement, since patients receiving dialysis are amongst the highest risk for death if hospitalized with COVID-19.”

Vaccine efficacy ‘uncertain’ in dialysis recipients

In the second study, Rémi Goupil, MD, MSc, a nephrologist at Hôpital du Sacré-Coeur de Montréal in Canada, and colleagues reported that the efficacy of the Pfizer/BioNTech vaccine among patients on hemodialysis “remains uncertain.”

The researchers analyzed serial plasma from 154 dialysis recipients (135 did not have a prior SARS-CoV-2 infection) and 40 health care worker controls (half did not have a prior SARS-CoV-2 infection) before and after their first dose of the Pfizer/BioNTech COVID-19 vaccine. They also evaluated convalescent plasma from 16 dialysis recipients who survived COVID-19.

“We sought to determine whether short-term antibody responses after a single dose of the [Pfizer-BioNTech] mRNA vaccine are comparable between patients receiving hemodialysis and healthy individuals, and how this compares with antibody responses in patients receiving hemodialysis who survived natural infection with SARS-CoV-2,” Goupil and colleagues wrote in the Canadian Medical Association Journal.

The researchers reported that among patients without a prior SARS-CoV-2 infection, they did not observe anti-RBD IgG levels in 57% (95% CI, 47-65) of dialysis recipients and 5% (95% CI, 1-23) of controls. None of the patients with nondetectable anti-RBD levels by week 4 had detectable levels by week 8. The results were similar among non-immunosuppressed and younger individuals, according to Goupil and colleagues.

Among those with a prior SARS-CoV-2 infection, median anti-RBD IgG levels at week 8 in dialysis recipients were comparable to controls at week 3 (P = 0.3) and to convalescent plasma from dialysis recipients who recovered from COVID-19 (P = 0.8).

Based on their results, the researchers recommended prioritizing dialysis recipients for the second dose of the Pfizer/BioNtech vaccine within the recommended 3-week interval, “and that rigorous SARS-CoV-2 infection prevention and control measures be continued in hemodialysis units until vaccine efficacy is known.”

References:

Anand S, et al. Ann Intern Med. 2021;doi:10.7326/M21-0256.

Goupil R, et al. CMAJ. 2021;doi:10.1503/cmaj.210673.