Specific diagnostic tests can detect past COVID-19 infection after clinical recovery
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Multiple peer-reviewed studies and official health guidelines confirm that specific diagnostic tests, namely serological antibody tests, can detect past COVID-19 infection and identify individuals following clinical recovery.
<h4>Background</h4>The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus and resulting COVID-19 pandemic present important diagnostic challenges. Several diagnostic strategies are available to identify current infection, rule out infection, identify people in need of care escalation, or to test for past infection and immune response. Serology tests to detect the presence of antibodies to SARS-CoV-2 aim to identify previous SARS-CoV-2 infection, and may help to confirm the presence of current infection.<h4>Objectives</h4>To assess the diagnostic accuracy of antibody tests to determine if a person presenting in the community or in primary or secondary care has SARS-CoV-2 infection, or has previously had SARS-CoV-2 infection, and the accuracy of antibody tests for use in seroprevalence surveys.<h4>Search methods</h4>We undertook electronic searches in the Cochrane COVID-19 Study Register and the COVID-19 Living Evidence Database from the University of Bern, which is updated daily with published articles from PubMed and Embase and with preprints from medRxiv and bioRxiv. In addition, we checked repositories of COVID-19 publications. We did not apply any language restrictions. We conducted searches for this review iteration up to 27 April 2020.<h4>Selection criteria</h4>We included test accuracy studies of any design that evaluated antibody tests (including enzyme-linked immunosorbent assays, chemiluminescence immunoassays, and lateral flow assays) in people suspected of current or previous SARS-CoV-2 infection, or where tests were used to screen for infection. We also included studies of people either known to have, or not to have SARS-CoV-2 infection. We included all reference standards to define the presence or absence of SARS-CoV-2 (including reverse transcription polymerase chain reaction tests (RT-PCR) and clinical diagnostic criteria).<h4>Data collection and analysis</h4>We assessed possible bias and applicability of the studies using the QUADAS-2 tool. We extracted 2x2 contingency table data and present sensitivity and specificity for each antibody (or combination of antibodies) using paired forest plots. We pooled data using random-effects logistic regression where appropriate, stratifying by time since post-symptom onset. We tabulated available data by test manufacturer. We have presented uncertainty in estimates of sensitivity and specificity using 95% confidence intervals (CIs).<h4>Main results</h4>We included 57 publications reporting on a total of 54 study cohorts with 15,976 samples, of which 8526 were from cases of SARS-CoV-2 infection. Studies were conducted in Asia (n = 38), Europe (n = 15), and the USA and China (n = 1). We identified data from 25 commercial tests and numerous in-house assays, a small fraction of the 279 antibody assays listed by the Foundation for Innovative Diagnostics. More than half (n = 28) of the studies included were only available as preprints. We had concerns about risk of bias and applicability. Common issues were use of multi-group designs (n = 29), inclusion of only COVID-19 cases (n = 19), lack of blinding of the index test (n = 49) and reference standard (n = 29), differential verification (n = 22), and the lack of clarity about participant numbers, characteristics and study exclusions (n = 47). Most studies (n = 44) only included people hospitalised due to suspected or confirmed COVID-19 infection. There were no studies exclusively in asymptomatic participants. Two-thirds of the studies (n = 33) defined COVID-19 cases based on RT-PCR results alone, ignoring the potential for false-negative RT-PCR results. We observed evidence of selective publication of study findings through omission of the identity of tests (n = 5). We observed substantial heterogeneity in sensitivities of IgA, IgM and IgG antibodies, or combinations thereof, for results aggregated across different time periods post-symptom onset (range 0% to 100% for all target antibodies). We thus based the mai
<h4>Objective</h4>To determine the diagnostic accuracy of serological tests for coronavirus disease-2019 (covid-19).<h4>Design</h4>Systematic review and meta-analysis.<h4>Data sources</h4>Medline, bioRxiv, and medRxiv from 1 January to 30 April 2020, using subject headings or subheadings combined with text words for the concepts of covid-19 and serological tests for covid-19.<h4>Eligibility criteria and data analysis</h4>Eligible studies measured sensitivity or specificity, or both of a covid-19 serological test compared with a reference standard of viral culture or reverse transcriptase polymerase chain reaction. Studies were excluded with fewer than five participants or samples. Risk of bias was assessed using quality assessment of diagnostic accuracy studies 2 (QUADAS-2). Pooled sensitivity and specificity were estimated using random effects bivariate meta-analyses.<h4>Main outcome measures</h4>The primary outcome was overall sensitivity and specificity, stratified by method of serological testing (enzyme linked immunosorbent assays (ELISAs), lateral flow immunoassays (LFIAs), or chemiluminescent immunoassays (CLIAs)) and immunoglobulin class (IgG, IgM, or both). Secondary outcomes were stratum specific sensitivity and specificity within subgroups defined by study or participant characteristics, including time since symptom onset.<h4>Results</h4>5016 references were identified and 40 studies included. 49 risk of bias assessments were carried out (one for each population and method evaluated). High risk of patient selection bias was found in 98% (48/49) of assessments and high or unclear risk of bias from performance or interpretation of the serological test in 73% (36/49). Only 10% (4/40) of studies included outpatients. Only two studies evaluated tests at the point of care. For each method of testing, pooled sensitivity and specificity were not associated with the immunoglobulin class measured. The pooled sensitivity of ELISAs measuring IgG or IgM was 84.3% (95% confidence interval 75.6% to 90.9%), of LFIAs was 66.0% (49.3% to 79.3%), and of CLIAs was 97.8% (46.2% to 100%). In all analyses, pooled sensitivity was lower for LFIAs, the potential point-of-care method. Pooled specificities ranged from 96.6% to 99.7%. Of the samples used for estimating specificity, 83% (10 465/12 547) were from populations tested before the epidemic or not suspected of having covid-19. Among LFIAs, pooled sensitivity of commercial kits (65.0%, 49.0% to 78.2%) was lower than that of non-commercial tests (88.2%, 83.6% to 91.3%). Heterogeneity was seen in all analyses. Sensitivity was higher at least three weeks after symptom onset (ranging from 69.9% to 98.9%) compared with within the first week (from 13.4% to 50.3%).<h4>Conclusion</h4>Higher quality clinical studies assessing the diagnostic accuracy of serological tests for covid-19 are urgently needed. Currently, available evidence does not support the continued use of existing point-of-care serological tests.<h4>Study registration</h4>PROSPERO CRD42020179452.
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its associated coronavirus disease 2019 (COVID-19) pandemic has demanded rapid upscaling of in-vitro diagnostic assays to enable mass screening and testing of high-risk groups, and simultaneous ascertainment of robust data on past SARS-CoV-2 exposure at an individual and a population level. To meet the exponential demand in testing, there has been an accelerated development of both molecular and serological assays across a plethora of platforms. The present review discusses the current literature on these modalities, including nucleic acid amplification tests, direct viral antigen tests and the rapidly expanding laboratory-based and point of care serological tests. This suite of complementary tests will inform crucial decisions by healthcare providers and policy makers, and understanding their strengths and limitations will be critical to their judicious application for the development of algorithmic approaches to treatment and public health strategies.
Validated and accurate laboratory testing for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is a crucial part of the timely management of Coronavirus Disease 2019 (COVID-19) disease, supporting the clinical decision-making process for infection control at the healthcare level and detecting asymptomatic cases. This would facilitate an appropriate treatment, a prompt isolation and consequently deceleration of the pandemic. Various laboratory tests can identify the genetic material of SARS-CoV-2 that causes COVID-19 in specimens, or specific anti-viral antibodies in blood/serum. Due to the current pandemic situation, a development of point-of-care diagnostics (POCD) allows us to substantially accelerate taking clinical decisions and implement strategic planning at the national level of preventative measures. This review summarizes and compares the available POCD and those currently under development, including quantitative reverse transcription PCR (RT-qPCR), serology immunoassays (SIAs) and protein microarray method (PMM) designed for standard and rapid COVID-19 diagnosis.
Serology (antibody) tests to detect previous SARS-CoV-2 infection have been in high demand from the beginning of the COVID-19 pandemic. The initial shortage of diagnostic tests coupled with asymptomatic infections led to a significant demand for serology tests to identify past infections. ABSTRACT Serology (antibody) tests to detect previous SARS-CoV-2 infection have been in high demand from the beginning of the COVID-19 pandemic. The initial shortage of diagnostic tests coupled with asymptomatic infections led to a significant demand for serology tests to identify past infections. Despite serious limitations on the interpretation of a positive antibody test in terms of immunity to SARS-CoV-2, antibody testing was initially considered for release from social distancing, return to employment, and “immunity passports.” The regulatory approach to antibody tests was limited; manufacturers were encouraged to develop and market antibody tests without submitting validation data to the FDA. FDA guidance grew more stringent, but many poor-quality tests were already on the market—potentially inappropriately used for individual decision-making. This is a case study describing COVID-19 serology tests and the U.S. market and describes lessons learned for a future health security crisis.
The consequences of past COVID-19 infection for personal health and long-term population immunity are only starting to be revealed. Unfortunately, detecting past infection is currently a challenge, limiting clinical and research endeavors. Widely available anti-SARS-CoV-2 antibody tests cannot differentiate between past infection and vaccination given vaccine-induced anti-spike antibodies and the rapid loss of infection-induced anti-nucleocapsid antibodies. Anti-membrane antibodies develop after COVID-19, but their long-term persistence is unknown. Here, we demonstrate that anti-membrane IgG is a sensitive and specific marker of past COVID-19 infection and persists at least one year. We also confirm that anti-receptor binding domain (RBD) Ig is a long-lasting, sensitive, and specific marker of past infection and vaccination, while anti-nucleocapsid IgG lacks specificity and quickly declines after COVID-19. Thus, a combination of anti-membrane and anti-RBD antibodies can accurately differentiate between distant COVID-19 infection, vaccination, and naive states to advance public health, individual healthcare, and research goals.
The world is going through a serious health crisis due to the COVID 19 pandemic. Although little is known about COVID-19, we have observed an increased interhuman transmission of etiological agent SARS-Cov-2 and we assume that each new cases of COVID-19 get at least two or three news persons infected. Therefore, the test for detection of the infection should be much implemented as an efficient strategy to fight against the COVID 19 pandemic. The COVID-19 diagnostic tests are an essential tool for assessing the pandemic. This review paper will discuss the advantages and limitations of the diagnosis tests for COVID 19. There are 2 categories of tests: those that directly detect the virus or its component, and those that search for the antibodies generated by the virus infection. The real time Reverse transcriptase Polymerase chain reaction (test rt-RT-PCR) remains the gold standard for the diagnosis of COVID-19. Its sensitivity on the nasopharynx swab seems high, though false negative cases can occur, with an average of 30% of cases. Serological test detect specific antibodies against SARS-COV-2. They help identify individuals that have been infected by the virus, those healed and that have acquired immunity against the virus. They are diagnosis orientation tests of COVID-19. Until now, none of these tests are 100% reliable, but they are used by a qualified collaborating medical staff. They can help identify the majority of the infected and immunized individuals. Le monde entie
ABSTRACT The onset of the COVID-19 pandemic resulted in hundreds of in vitro devices coming to market, facilitated by regulatory authorities allowing “Emergency Use,” without a prior comprehensive evaluation of performance. The World Health Organization released Target Product Profiles specifying acceptable performance characteristics for SARS-CoV-2 devices. We evaluated 16 automated serology test kits that detect IgG or Total antibodies to SARS-CoV-2, along with a further nine tests that detect IgM-specific antibodies. All IgG or Total antibody tests reported a concordance with recent infection at 83.9% or greater, with 11/16 tests having greater than 90% sensitivity. All 16 tests reported greater than 96.3% specificity. There was a low level of false reactivity when testing all 25 tests on panels of samples containing potentially cross-reacting or interfering substances. A range of results were reported when testing seroconversion and dilution panels. The study further demonstrates that a comprehensive evaluation of the performance of test kits assessed against defined specifications is essential for the selection of test kits, especially in a pandemic setting. IMPORTANCE We have previously highlighted the fact that hundreds of SARS-CoV-2 serology tests were released months after the onset of the COVID-19 pandemic. Of the hundreds of studies investigating the test kits’ performance, few were comparative reports, using the same comprehensive sample set across multiple tests.
This article presents a non-systematic review of the literature focusing on the diagnostic challenges and laboratory differentiation between acute respiratory viral infections (ARVI) and COVID-19 in resource-limited settings of India and Kyrgyzstan. A non-systematic search of PubMed and Google Scholar was conducted for articles published in 2025-2026. The search strategy used the terms “diagnosis” OR “diagnostic” OR “diagnostic tests” OR “tests” AND “COVID-19” OR “SARS-CoV-2” OR “acute respiratory viral infections (ARVI)” in the article title and keywords. Diagnostic tests for respiratory viral infections primarily detect viral nucleic acid or host immune responses. In COVID-19, identification of SARS-CoV-2 RNA by real-time polymerase chain reaction (RT-PCR) from respiratory specimens remains the reference standard, particularly during the early phase of illness. In contrast, ARVI diagnosis in resource-limited settings often relies on clinical features with limited laboratory confirmation due to restricted access to molecular testing. Serological assays are more informative in the later stages of infection and may support retrospective diagnosis or epidemiological assessment. Routine laboratory parameters such as complete blood count, C-reactive protein (CRP), D-dimer, coagulation profile, lactate dehydrogenase (LDH), ferritin, and procalcitonin help assess disease severity, inflammatory status, thrombotic risk, and prognosis rather than providing etiological confirmation. Im
COVID -19 (coronavirus disease 2019) is a disease caused by a virus called SARS-CoV-2. There are two types of tests for this virus: A viral test tells you if you have a current infection. Viral tests can either be rapid tests or laboratory tests: Rapid tests can be done in minutes. They are often antigen tests, which look for specific proteins from the virus. Some rapid tests are self-tests which you can do at home. Laboratory tests can take days to complete and include PCR tests. An antibody (serology) test might tell you if you had a past infection. If you need a COVID -19 test, you can: Buy a self-test online or at a store. Make sure that the test you buy has been authorized by the U.S. Food and Drug Administration (FDA). Check your state or local health department's website for information on testing in your area. Contact your health care provider. Even if your COVID -19 viral test is negative (the test did not detect the virus), you should still take steps to protect yourself and others. Centers for Disease Control and Prevention
you if:
You currently have COVID-19, the disease caused by the SARS-CoV-2 virus,
You have immunity that will prevent COVID-19,
You need a COVID-19 vaccine, or
Your COVID-19 vaccine worked.
On this page:
Antibodies and Antibody Tests: The Basics
Antibody Tests: Not for Use to Check Immunity
Antibody Tests: Results and Terms
Additional Resources
Antibodies and Antibody Tests: The Basics
Q: What are antibodies?
A: Antibodies are proteins made by your body's immune system to help fight off infections, including those caused by viruses. Some antibodies in your body may protect you from getting those infections. Your immune system can also safely learn to make antibodies through vaccination. If antibodies give you this protection and how long this protection lasts can be different for each disease and each person. Antibodies are just one part of your immune response.
Q: Are antibody tests used to diagnose COVID-19?
A: No. An antibody test cannot be used to diagnose current COVID-19 because an antibody test does not detect SARS-CoV-2. Only COVID-19 diagnostic tests can be used to diagnose current COVID-19. A positive antibody test result can be used to help identify people who may have had a prior SARS-CoV-2 infection or prior COVID-19. An antibody test does not show if you have a current SARS-CoV-2 infection or COVID-19 because the antibodies are part of the body's immune response to infection, and antibody tests do not test for the virus itself. It also can take days to weeks after the infection for your body to make detectable antibodies.
Antibody Tests: Not for Use to Check Immunity
Q: Will a positive result on a SARS-CoV-2 antibody test mean I have immunity and I will not get COVID-19?
A: No. At this time, SARS-CoV-2 antibody tests do not tell you if you have immunity that will prevent you from getting COVID-19. A positive SARS-CoV-2 antibody test does not necessarily mean you are immune or have immunity that will prevent COVID-19. More research is needed to understa
The unprecedented outbreak of COVID-19, caused by SARS-CoV-2, is the biggest international challenge since World War II. The fight against this pandemic has urged the scientific community to direct massive efforts toward developing accurate and timely testing methods. The current COVID-19 tests fall into two general categories: nucleic acid amplification tests (NAAT), also known as molecular tests, and serological or antibody-based tests. Molecular tests directly detect the genome of the pathogen, whereas serological tests detect antibodies produced in response to the pathogen. Alternative testing platforms, such as radiological imaging of the lungs and tests based on the detection of viral antigens, have been also employed for diagnosing COVID-19. Each diagnostic platform has its own merits and demerits considering various parameters. Due to SARS-CoV-2’s high transmissibility rate, specific and accurate diagnostic methods for large-scale screening of patients is vital. Here, we will highlight the characteristics of various diagnostic and surveillance techniques that are currently available for SARS-CoV-2 detection and provide implications for more accurate testing. This topic is rapidly evolving, and a review that covers novel approaches needed to diagnose COVID-19 may be useful in choosing the appropriate detection method. Some of these methods are in the proof-of-concept stage of development, and further clinical evaluation is required.
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