COVID-19: Testing herd immunity without “unethical” and “unachievable” vaccines | 2020-07-06

Large scale epidemiology Investigation Advance online publication, issued on July 6, 2020 Lancet We found that most individuals infected with SARS-CoV-2 developed antibodies to the virus, confirming that the infection usually resulted in an immune response of at least a short duration.

However, antibody tests show that at least one-third of SARS-CoV-2 infections are asymptomatic, with some patients rapidly declining in antibody response and vulnerable to reinfection. There was a nature.

And even in Spain, an early hotspot for pandemics, only about 5% of individuals had antibodies to the virus-necessary to achieve what is known as herd immunity. Well below the estimated 70%.

Many SARS-CoV-2 infections remain asymptomatic, and the ability of SARS-CoV-2 to spread via asymptomatic infections complicates attempts to understand its epidemiology and spread. So far, the basic questions of the pandemic remain unanswered

The ENE-COVID study should document how much of the Spanish population was exposed nationally and how exposure varied by region and by demographic factors such as age and gender. Designed to

In their study, the authors repeatedly tested 61,000 people out of 36,000 households across Spain for antibodies to SARS-CoV-2. They used two separate tests, a point-of-care test and an additional laboratory assay in individuals who agreed to donate blood. Participants were also asked about COVID-19 symptoms.

Overall, about 5% of the population had antibodies to the virus. Antibody prevalence was high in hotspot areas, but less than 15% in severely affected areas.

Antibodies indicate exposure, but they are not a sure sign of immunity. How well they protect against reinfection depends on their staying power and the viral antigens they target.

Conversely, recent papers Posted To bioRxiv A preprint server by the Karolinska Institute COVID-19 study group found SARS-CoV-2 specific memory T cells in some individuals with no antibody and in some individuals with mild or asymptomatic infections. I reported that I found it.

In the ENE-COVID study, symptoms, diagnoses, and antibody outcomes were, at least, not closely correlated. At least one-third of antibody-positive patients were asymptomatic, and only about 20% of individuals who self-reported COVID-19-matched symptoms had a previous test.

Given the importance of large-scale testing for short-term return to non-isolated beings, one bright point is: “High-quality point-of-care tests are suitable for large-scale seroepidemiological studies. The Point of Care test they used in their study (Orient Gene Biotech COVID-19 IgG / IgM Rapid Test Cassette; Zhejiang Orient Gene Biotech, Zhejiang, China; reference GCCOV-402a) is a chemical Luminescent microparticle immunoassay. “

However, this data also strengthened the need for vaccines to achieve herd immunity and return to normal or new normals.

Within Europe, Sweden’s attempt to achieve herd immunity by avoiding blockades of the general population has resulted in one of the highest per capita COVID-19 mortality rates in the world. However, as of the end of April, about 7.4% of the Swedish population had antibodies to SARS-CoV-2.

so Explanation “The proposed approach to achieving herd immunity through natural infections is only very unethical,” said researchers at the Center for Emerging Viral Diseases at the University of Geneva, published with the results of the ENE-COVID study. It’s also unachievable.”

The study author himself pointed out the same. “Despite the great impact of COVID-19 in Spain”-the epicenter of post-Lombardy Europe outbreaks, with the highest number of cases diagnosed within the European Union-“Estimated prevalence To provide herd immunity that is low and apparently inadequate,” they wrote. Immunity of such a herd cannot be achieved without “accepting the collateral damage of many deaths in susceptible people and overburdening the health care system.”