Application: This product is for research use only and is not intended for diagnostic use.

Features: Quality Control
Each test should meet the OD value of the positive control ≥ 0.50 and the OD value of the negative control ≤ 0.10 at the same time; otherwise, the test results are considered invalid.

Calculation
Cut-off (cut off value) calculation: cut off value = 0.10 + negative control (Mean of negative control OD, if less than 0.05, calculate as 0.05)
Positive: If the OD value of the tested sample is greater than the cut-off value, it should be judged as positive for new-type coronavirus (SARS-COV-2) IgM antibody.
Negative: If the OD value of the tested sample is less than the cutoff value, it is judged as negative.
It is recommended to re-test near the cut-off value. If the re-test result is positive, it is judged as positive, otherwise it is judged as negative. Weakly positive samples for this product should be tested by other methods to exclude false positives. Notes:
1. Insufficient washing is the main cause of false positives;
2. Other operational errors may lead to false positives and false negatives of the test results, such as: the kit is used outside the validity period, the sampler is inaccurate, the indoor temperature is too low, and the test is not performed according to to the testing procedures of the instructions
3. The determination of positive results and negative results should be determined jointly based on clinical characteristics and other detection indicators.

Limit of Detection
3 reference products with minimum detection limits were tested, all of which were positive.

Reproducibility
Inter-assay: The assay control is tested in 10 replicates with a CV of OD values ​​less than 15%. Intra-assay: Three lots were tested with the same samples 10 times with a CV less than 20%.

Sensitivity & Specificity
Serum samples from two chhorts of patients were tested using the IgM ELISA Kit. The combined cohort consisted of normal healthy patients with samples collected prior to the SARS-COV-2 outbreak (n = 30) and RT-PCR confirmed positive patients in after the second week of the onset of the disease (n = 16).

The new coronavirus belongs to the beta coronavirus of the genus β, which has an envelope, the particles are round or oval, often polymorphic, and the diameter is 60-140nm. Its genetic characteristics are significantly different from SARSr-CoV and MERSr-CoV. Current research shows that it has more than 85% homology with bat SARS-like coronavirus (bat-SL- CoVZC45). In vitro isolation and culture, 2019-nCoV can be found in human respiratory epithelial cells in about 96 hours, while it takes about 6 days to isolate and culture in Vero E6 and Huh-7 cell lines. Based on current epidemiological investigations, the incubation period is generally 7 days, with a maximum of 14 days. Main symptoms are fever, fatigue, and dry cough. A few patients have symptoms such as nasal congestion, runny nose, and diarrhea. In severe cases, dyspnea occurs more than a week later. In severe cases, acute respiratory distress syndrome, septic shock, difficult to correct metabolic acidosis, and coagulation dysfunction develop rapidly. It is worth noting that in the course of severe and critically ill patients, there may be moderate to low fever, even without obvious fever. Some patients showed only low fever, mild fatigue, and no pneumonia and recovered after 1 week. In the early stages of the disease, the total number of white blood cells in the peripheral blood was normal or decreased, the lymphocyte count decreased, and some patients had increased liver enzymes, muscle enzymes, and myoglobin. Most patients have elevated C-reactive protein (CRP) and erythrocyte sedimentation rate and normal procalcitonin. In severe cases, D-dimer increases and peripheral blood lymphocytes progressively decrease. New coronavirus nucleic acids can be detected in throat swabs, sputum, lower respiratory tract secretions, and blood. [1] Serum antibody testing helps confirm the infection status of a case.