In late , a cluster of cases of viral pneumonia of unknown aetiology was reported in Wuhan, Hubei Province, China. This new viral pneumonia, COVID-19 (Coronavirus Disease ), caused by the novel SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus-2), spread rapidly and developed into a global pandemic within three months from its initial detection [1&#;3]. Among other symptoms, those of COVID-19 often include fever and dry cough, which resemble respiratory illnesses caused by other viruses or bacteria [4&#;7]. Due to the overlapping manifestations, clinical diagnosis becomes problematic, especially during seasonal flu [8], why confirmation of COVID-19 depends on the detection of SARS-CoV-2 nucleic acid by reverse-transcriptase polymerase chain reaction (RT-PCR).
If you want to learn more, please visit our website Accu-Tell.
More than 1.26 million cases of COVID-19 in > 200 countries and territories, with more than 66.000 human deaths, have been reported ([9], 5 April ). Due to the limited testing in many geographical regions, it is clear that the total number of actual COVID-19 cases is much higher than the number of confirmed ones. In most of the confirmed COVID-19 cases, the patients are symptomatic showing fever, dry cough, and pneumonia, but also more atypical symptoms such as gastrointestinal manifestations as well as anosmia and ageusia. However, the virus has been detected in completely asymptomatic individuals, e.g. in a recent study from Italy, showing that 44% of the laboratory-confirmed cases lacked symptoms [10]. The knowledge concerning the actual number of asymptomatic vs. symptomatic infections is still limited. The same is true for the potentially growing herd immunity, where almost no data is available to date.
In the present study, we evaluated a commercially available assay, the COVID-19 IgG/IgM Rapid Test Cassette (Zhejiang Orient Gene Biotech Co Ltd, Huzhou, Zhejiang, China), developed for detection of SARS-CoV-2-specific antibodies.
In this study we evaluated a commercial rapid test for detection of SARS-CoV-2-specific IgM and IgG. For the evaluation, samples from COVID-19 cases, obtained during disease or convalescence and previously confirmed by PCR, were used as &#;true positives&#;. This means that in the PCR-positive cases for which antibodies may not yet had time to develop, or in potential cases with immune defects, it is possible that the negative IgM or IgG results were in fact true negatives. If this was the case for one or more of the included patients, the actual sensitivities should be higher, i.e. when evaluated only on samples known to contain detectable levels of SARS-CoV-2-specific IgM and/or IgG. For a more optimal evaluation of the assay sensitivity, a gold standard for SARS-CoV-2-specific antibodies would have been needed. This is, however, unfortunately not available to date.
According to the manufacturer, the specificity has been evaluated on 14 PCR-negative samples and was found to be 100% for both IgM and IgG, while the sensitivity evaluated on COVID-19 cases was calculated at 87.9% for IgM and 97.2% for IgG. The results by Li et al. [11] indicated an overall testing sensitivity of 88.7% and 90.6% specificity. Our results showed a lower sensitivity for IgM, a similar sensitivity for IgG, and specificities in between the results of the two evaluations.
A recent study on three Chinese COVID-19 cases found that seroconversions occurred between 7 and 12 days after the onset of symptoms [12]. However, larger studies on the detailed kinetics of the antibody responses (e.g. IgA, IgM, IgG, neutralizing antibodies) are now urgently needed for a better understanding of the dynamics of the immune response during COVID-19. The results of our study showed detectable IgM and IgG in some patients at day 9, while in other patients the seroconversion seems to occur later. The impact of early or late seroconversion on the case severity is not known, and must now be explored. Interestingly, there were no IgM positives that were not IgG positive. Generally, IgM is produced first, and later there is a switch towards IgG production [13], but studies on SARS-CoV suggest that IgM and IgG often develop around the same time [14,15]. Our results are in line with this (Figure 1), but more detailed studies on long-term sequential samples from patients are now needed. It may be worth looking into whether this is a problem with the test, or a constant finding within the immune response to SARS-CoV-2.
There were no false IgM positive samples, indicating a very high specificity of the test. One false positive IgG result was observed for one healthy adult blood donor. This sample was re-tested and the result was consistent, indicating a cross-reaction to another coronavirus. Serological cross-reactions have earlier been observed between SARS-CoV and SARS-CoV-2 [16]. There are other human coronaviruses (NL63, OC43, 229E, and HKU1) that are globally endemic or epidemic [17], and it may be possible that this reaction represented a cross-reaction due to a previous infection with one of those. Human CoV NL63 has been shown to use the same receptor, angiotensin-converting enzyme 2 (ACE2), as SARS-CoV and SARS-CoV-2 [18], which may indicate potential cross-reactive epitopes. How common the CoVs are as causative agents for &#;common colds&#; is not known in detail, but there has been estimates that up to 20% of cases could be caused by CoVs [19].
The specificity and sensitivity for IgG detection of the rapid test evaluated here is well in line with those of a recently reported enzyme-linked immunosorbent assay (ELISA), which had a specificity and a sensitivity of 97.5% [20].
While this study showed a satisfactory performance of the rapid test, it is limited by being compared only to clinical cases and PCR-positivity, and as a next step, it is necessary to compare this assay to other serological tests. In contrast to Li et al. [11], we found less indications for using this test for clinical diagnosis. Nevertheless, it might contribute to detecting potential asymptomatic infections as well as getting a notion of the magnitude of the spread in different geographical areas, which might be a key to taking the appropriate decisions and policies forward. The high negative predictive value indicates that the rapid test will be useful for detecting past infections and possible immunity, which may be crucial for restoring social functions after lockdown.
Want more information on IgG Rapid Test Cassette Supplier? Feel free to contact us.
Clinical performance of the kit varies for the detection of IgG and IgM antibodies.
For SARS-CoV-2 IgM antibodies, RapidFor&#; IgG/IgM Test Kit has demonstrated 98.23% sensitivity and 99.12% specificity with a total coincidence rate of %98.71.
For SARS-CoV-2 IgG antibodies RapidFor&#; IgG/IgM Test Kit has demonstrated %97.97 sensitivity, and %99.37 specificity, with a total coincidence rate of %98.69.
RapidFor&#; IgG/IgM Test Kit allows for safe, minimally invasive, and painless sample collection with finger puncture technique. Please follow the instructions carefully to ensure maximum safety, comfort, and accuracy. Refrain from piercing your finger any further than instructed. While mild discomfort is possible during sample collection, make sure to stop the procedure and seek medical help if you experience serious pain.
Yes. If your result is positive only for IgG antibodies, which appear in the blood 2-3 weeks after the onset of symptoms and provide long-term immunity against COVID-19, it indicates a past infection with SARS-CoV-2. On the other hand, the presence of IgM antibodies reveals an early immune response against COVID-19, which indicates recent infection with SARS-CoV-2.
Please read the instructions thoroughly before starting the procedure. The procedure should be concluded within 15 minutes after the test cassette is removed from the foil package. Please make sure to recap the buffer solution quickly after each use and utilize the sample as soon as possible. The sample should be used within 30 minutes at most, inactivation of samples is not recommended.
After the process, all samples and materials should be placed in the aluminum foil and disposed of as biohazardous waste as soon as possible. Please refrain from using the recycling bin for disposal and make sure that animals and children are out of reach.
A positive result with RapidFor&#; IgG/IgM Test Kit indicates previous exposure to SARS-CoV-2. You may contact your healthcare provider to get more information and medical assistance if necessary.
A negative result may indicate that your IgG antibody level may be insufficient for detection with RapidFor&#; Rapid IgG/IgM Test Kit. Please keep in mind that negative results may occur in the early phases of infection because the antibodies may take a while to appear after infection or vaccination. You may consider having another test within 4-5 days to reassess your antibody levels against SARS-CoV-2.
RapidFor&#; Rapid IgG/IgM Test Kit can be stored be between 2°C-30°C and within 40-60% of humidity in the sealed package until its expiration date. Please make sure to check the label on the packaging for the manufacturing and expiration dates. Do not store the kit below 2°C or use it after expired date.
For more information, please visit hsv rapid test.