There was a detectable COVID antibody in U.S. studies that was barely in Spanish

Ah Investigation Published yesterday Lancet Only 4.6% of survey respondents across Spain found in an immunoassay that they had antibodies in their serum against SARS-CoV-2, the virus that causes COVID-19.

Also, Investigation yesterday Clinical infection Of the 249 front-line health workers in Nashville, Tennessee, 19 (7.6%) tested positive for antibodies to the novel coronavirus, of which only 11 reported COVID-19 symptoms. ing.

Immunity of natural herds is still distant

In the first study, conducted from April 27 to May 11, Madrid researchers tested both 61,075 people in the point-of-care test and 51,958 people in the immunoassay. Estimates of serum prevalence in both tests were similar.

They found that the presence of antibodies against SARS-CoV-2 did not differ by gender, but immunoassays confirmed that children under 10 years of age and adults over 85 years of age had low serum prevalence. Serum prevalence varied widely by region, with over 10% in central Spain around Madrid. 5% in Barcelona. And less than 3% along the other parts of the coast.

The seroprevalence of 195 participants who had a positive polymerase chain reaction (PCR) test more than 14 days prior to study visit was 87.6% of those who had both a positive point-of-care test and an immunoassay. , Both tests are positive.

About one-third of people who test positive for antibodies report no symptoms. Only 19.5% of those with symptoms that were positive for antibodies by both point-of-care tests and immunoassays said they had previously had a PCR test.

Of the 7,273 participants who reported odor loss or at least 3 other COVID-19 symptoms, serum prevalence was 15.3% to 19.3%. Healthcare workers had a higher seroprevalence than other occupations (8.3% for both types of tests to 11.7% positive for either test). In Spain, healthcare workers account for 24% of all COVID-19 cases and 9% of all hospital admissions in that age group.

“These results underscore the need to maintain public health measures to avoid new epidemics,” the authors write. “Measuring social distances and efforts to identify and isolate new cases and their contacts are essential to controlling future epidemics.”

so Explanation In the same journal, Dr Isabella Ecker of Medicine at the Center for Emerging Viral Diseases in Geneva and Dr Benjamin Meyer at the University of Geneva, a key finding in this study is that most populations appear unexposed to coronavirus. Even in areas where viral activity is widespread, he said.

“These findings are further supported by the observation that even countries without strict blockades report similarly low serum prevalence. For example, in Sweden, at the end of April, 7.3% prevalence was observed. Reported the morbidity, “they wrote.

Eckerle and Meyer suggest that seroprevalence studies only measured previous exposures, not immunity, suggesting immunity to SARS-CoV-2 is incomplete and transient. I pointed out that some research is being done.

“In light of these findings, the proposed approach to achieving herd immunity through natural infection is not only unethical, but unachievable,” they said. “Because the vast majority of the population is uninfected, the virus cycle could quickly return to the early dimensions of a pandemic in the second wave if the measures are lifted.”

The role of PCR testing in all healthcare professionals

Secondly InvestigationResearchers at Vanderbilt University, enrolled front-line health workers who looked after COVID-19 patients in the first month of the epidemic in the United States. Staff at the Centers for Disease Control and Prevention (CDC) perform serological tests using a new enzyme-linked immunosorbent assay (ELISA) developed by CDC that has a sensitivity of approximately 96% and a specificity of 99%. did.

Most healthcare workers were young (median age, 33 years) and 79% had no underlying illness. Of the 249 workers, 147 (59.0%) worked mainly in the emergency department, 55 (22.1%) worked in the intensive care unit, and 47 (18.9%) worked in other areas.

Testing for antibody positives for SARS-CoV-2 is more common among workers who say they do not always wear personal protective equipment (PPE) for contact with all patients (15.8%). did.

Seven of the 19 participants who tested positive for antibodies (36.8%) reported that they thought they had previously had COVID-19. Among those who tested positive for antibodies, the most common symptoms were cough (9), sore throat (6) and myalgia (4).

Of the 19 workers with detectable antibodies to SARS-CoV-2, 7 (36.8%) had previously undergone a coronavirus PCR (nucleic acid) test, at which point a positive result was obtained. Only three were given.

“The majority of health-care workers who tested positive for serochemistry had never been infected or had a previous SARS-CoV-2 nucleic acid test,” the authors write. “Increasing surveillance of SARS-CoV-2 infections, including routine point-of-care nucleic acid testing of health-care workers, will prevent SARS-CoV-2 infections from health-care workers with asymptomatic and minimal symptoms. It could be an important strategy to reduce.”