CORONA: How many people are immune?

Robert Koch Institute starts nationwide antibody studies

(Press release: Robert Koch Institute, April 2020, photo: PR)

How widespread is the new SARS-CoV-2 coronavirus actually spread in Germany? How many people have gone through an infection and are now immune at least for a while? Scientists at the Robert Koch Institute want to find out in several large-scale studies. It is investigated whether antibodies to SARS-CoV-2 can be detected in the blood of the study participants - a sure indication of a past infection.

"From these studies, we expect a more precise picture of the SARS-CoV-2 events in Germany," said Prof. Lothar H. Wieler, President of the RKI.

It is not yet known how many people in Germany have actually gone through an infection and are therefore immune. The infection is often mild or even unnoticed. "The results of the antibody studies are of great importance in order to assess the course and severity of the pandemic more precisely and to be able to better assess the effectiveness of the measures taken," emphasizes Wieler.

Infection with SARS-CoV-2 is notifiable in Germany. However, the official reporting numbers only reflect part of the SARS-CoV-2 infections. Not everyone infected develops symptoms so severe that they go to the doctor, and not everyone with symptoms is tested. With the currently used PCR tests, only an acute infection can be detected: The test detects the genetic makeup of the virus, usually in throat swabs. In antibody or serological studies, the blood of the test subjects is tested for antibodies against SARS-CoV-2. Antibodies can be detected at the earliest one to two weeks after infection; Appropriate laboratory tests have only recently become available.

The RKI will shortly begin investigations on blood donors and people in some COVID-19 outbreak areas. In the longer term, a nationwide representative study is planned.

In laboratory analysis, the RKI works closely with the Institute for Virology at the Charité - Universitätsmedizin Berlin, headed by Prof. Christian Drosten.

An overview of the studies

Serological examination of blood donors in Germany: In cooperation with the blood donation services, blood samples from adults from all over Germany are regularly checked for antibodies. This enables conclusions to be drawn about the spread of SARS-CoV-2 in the population. As of next week, approximately 5,000 blood samples are to be examined every 14 days. First results are expected in early May 2020.

Seroepidemiological studies in several particularly affected places ("hotspots") in Germany: The aim of the localized studies is to estimate the immunity of the local population by determining antibodies against SARS-CoV-2 in representative samples of the residents. The proportion of asymptomatic infections and risk factors for a severe course in the population should also be better estimated. Around 2,000 volunteers aged 18 years and over are examined several times in each location. asked about clinical symptoms, previous illnesses, health behavior, living conditions and mental health. The course starts in mid-April 2020, with the first results expected in May 2020. The RKI works with researchers led by Prof. Gérard Krause from the Helmholtz Center for Infection Research in Braunschweig to plan and conduct these so-called “hotspot” studies.

Nationwide population-representative seroepidemiological study: By determining antibodies against SARS-CoV-2 in a nationwide representative sample, the actual spread, immunity, the proportion of asymptomatic infections, the actual death rate and risk factors for a severe course in the population in Germany should be better estimated . 15,000 people aged 18 and over are to be examined at 150 study locations. asked about clinical symptoms, previous illnesses, health behavior, living conditions and mental health. Studies are expected to start in mid-May 2020, with first results expected in June 2020.