key: cord-312646-hfv7ce3f
authors: Pfützner, Andreas
title: Comment to Döhla et al., Rapid point-of-care testing for SARS-CoV- 2 in a community screening setting shows low sensitivity
date: 2020-06-02
journal: Public Health
DOI: 10.1016/j.puhe.2020.05.048
sha: 
doc_id: 312646
cord_uid: hfv7ce3f

nan

Dear Editors, we have read with interest the manuscript by Döhla et al., which has been recently published by your journal [1] . In this manuscript, a point-of-care rapid test for assessment of anti-SARS-CoV-2 virus antibodies (IgG/IgM) is evaluated for sensitivity and specificity to detect the viral infection. The authors use a specific real-time polymerase chain reaction test (RT-PCR) as standard laboratory reference method. They found that the antibody rapid test only detects 36.4 % of the samples identified as positive by means of RT-PCR, and conclude that this POCT is not recommendable for community screenings.

Basically, the authors compare a test with moderate sensitivity (~70 %) to detect the viral RNA from a nasal or pharyngeal swab sample [2] with a blood test that measures the immune response of a host to the viral exposure. It is textbook knowledge that it takes about 5 to 10 days for IgM antibodies to become prevalent. So it is predictable from the chosen methodology that a substantial number of PCR-positive samples have to be negative in the antibody test. It is also predictable that an antibody test is not really suitable to identify newly infected subjects. And this is not how it should be used! A point-of-care antibody test can e.g. be used to differentiate people with past infections (and potential immunity) from people that have not had the infection yet. In case that recent reports are confirmed that people with past infections may become asymptomatic carriers of the SARS-CoV-2 virus [3] , the antibody tests may be the only way to differentiate PCR-positive subjects into two groups: i.) patients who are freshly infected and may soon develop clinical symptoms (negative IgG result) and ii.) patients who have developed antibodies and may now be asymptomatic virus spreaders (positive IgG result).

Performance evaluations for an antibody rapid test should only be done in a proper way and using a standard reference methods (e.g. a chemiluminescence method) that measures the same analyte. It would have been fair and scientific standard, if the authors would have pointed to the limitations of their study.

In any case our conclusion with respect to antibody testing is that the antibody detection offers vital clinical information during the course of the SARS-CoV-2 pandemic, and community testing will be warranted and necessary in the near-term future to reinstall normal life in our communities.

Yours sincerely

Rapid point-of-care testing for SARS-CoV-2 in a community screening setting shows low sensitivity

Antibody responses to SARS-CoV-2 in patients of novel coronavirus disease 2019

Virological assessment of hospitalized patients with COVID-2019