Study: Less than 10% of the US population had COVID-19 antibody

Based on a national sample of extrapolated dialysis patients in the US population, only 9.3% of US adults were seropositive for COVID-19 as of July (95% CI 8.8% -9.9%). ).

However, this figure is fairly high in the northeastern United States, the most devastating region in the United States, with an estimated 27.2% of the dialysis population nationwide being serum-positive (95% CI 25.9% -28.5%) and Shuchi of Stanford University. Dr. Anand is a colleague in Palo Alto, CA Lancet.. In the western states, the estimated serum prevalence was 3.5%.

Anand et al. Also compared the prevalence of sera per 100,000 population as of June 15 with the number of cases and found that there were relatively few seropositives actually diagnosed with COVID-19: 9.2% (95% CI 8.7% -9.8%).

In a statement, Stanford University co-author Julie Personnet, MD, said in a statement, “Despite the high rates of COVID-19 in the United States, the number of people with antibodies remains low and the herd Approaching to achieve immunity “-it usually requires about 70% of the population to be exposed and immunized.

An accompanying editorial by Dr. Burnaby Flower and Dr. Christina Atchison at Imperial College London, London, England, points out that the new study has several advantages over previous serum prevalence studies. First, previous studies used a “selection-biased sampling strategy” that “disproportionately affects some ethnic groups and deprived communities that are unlikely to participate in the study.” Has a problem. Second, a large study used the Point of Care Lateral Flow Assay, which is less sensitive than the lab assay performed by Anand’s group.

“This adds uncertainty and requires substantial adjustment of the raw data to explain the false-negative results,” they wrote.

Flower and Atchison praised the Siemens chemiluminescent assay used in the current study, “This is the best platform in the largest external assessment of commercial assays to date, both in terms of sensitivity and specificity. Is. “

Dr. Anand and colleagues hypothesized that patients undergoing dialysis could be an “ideal surveillance population for studying the evolution of the COVID-19 public health crisis.” At risk of severe COVID-19, “aging, non-white, poverty, diabetes” is common in this population.

“The first wave of COVID-19 outbreaks that can identify differences in serum prevalence between patient groups within and across the United States with a high level of accuracy and can be useful in providing strategic information. To target the vulnerable population and curb the epidemic, “Anand said in a statement.

In this study, Anand and colleagues partnered with a nationwide network of approximately 1,300 dialysis facilities serving approximately 65,000 patients. Other inputs included patient-level resident data, including cumulative daily cases and deaths per 100,000 people by Johns Hopkins University, and state-level nasal swab test positive rates by the Covid Tracking Project. .. Residence information was also associated with zip code-level socio-economic data from a five-year estimate from the 2018 American Community Survey.

Overall, it included 28,503 patients from 46 states with similar age, gender, race, and ethnic distribution to the US dialysis population. As expected, the dialysis population was larger than the general population, with older people, men, and the majority of black and Hispanic people living in the area.

Residents of predominantly non-Hispanic blacks (or 3.9, 95% CI 3.4-4.6) and Hispanics (or 2.3, 95% CI 1.9-2.6) may be more serum-positive than non-Hispanic Caucasian residents The sex was high. The highest population density was also associated with an increase in serum positive rates.

However, Flower and Atchison also pointed out a substantial limitation to the study: for one thing, extrapolating the serum prevalence of dialysis patients to the general population is “essentially problematic, even after adjustment. “. This population goes to medical facilities three times a week. In other words, the risk of SARS-CoV-2 may be high. Patients with end-stage renal disease are also less likely to initiate a detectable antibody response and are more likely to die of COVID-19.

Nonetheless, editors praised Anand’s group for this “blueprint” of a scalable sampling strategy for national surveillance in dialysis populations.

“General population estimates from dialysis sampling are incomplete, but at least nationally consistent, with longitudinal monitoring from one survey to the next,” writes Flower and Atchison.