There are several approaches that can be used to identify an infection, these focus on detecting either viral proteins (Early detection), viral nucleotide sequences (Early detection) or antibodies (Later detection) raised against specific viral components.

1. Quantitative Polymerase Chain Reaction (qPCR) is used for detecting specific nucleotide sequences of the virus. These nucleotide sequences encode proteins that are crucial for the virus to hijack cellular mechanisms to drive the production of new viral particles. These nucleotide sequences can be isolated and amplified using PCR, and further quantified using fluorescent probes using qPCR systems.


2. Enzyme-linked immunosorbent assays (ELISAs) provide a readout of antigen-antibody interactions.
   In the case of IgM/IgG antibody tests, patient antibodies are “sandwiched” between the deposited viral protein of interest and reporter antibodies, so that any active patient antibodies are detected.
   Antigen tests work similarly, but in that case the Antigen-specific capture antibody is deposited and the viral particles get captured between this and the labelled antigen-specific antibody. The labeling method can produce a visible signal (immunogold) or a fluorescent signal, that is revealed under UV-light. Rapid test kits, or Lateral Flow Assays (LFA) are based on the same principles, but are packaged into an easy to use, point-of-care format.
   


3. Neutralization tests can indicate whether the patient has active, functional antibodies to the pathogen in question by measuring how much the patient antibodies can inhibit viral growth in the lab.

The incubation period for the infection can vary from 2 to 14 days. This variation makes it difficult to pinpoint a timeframe when a person was infected and could vary by the same amount as the incubation period.

Patient antibodies (IgM/IgG) against the virus particles, which is tested by the COVID-19 IgM/IgG Rapid test kit, only appear after symptoms arise (1-3 weeks). The recommended time frame is 7 days after the onset of symptoms (87% Sensitivity), when IgMs and IgGs can be visually detected using the LFA kit. However, sensitivity improves over time and is over 95% 10 days post symptoms. Antigen Rapid test or RT-qPCR test is recommended to identify acute COVID-19.

The COVID-19 Viral Antigen Detection kit detects the Nucleocapsid (N) protein of the SARS-CoV-2 virus from naso- or oropharyngeal swabs, while the ProTect™ COVID-19 RT-qPCR kit is based on the direct molecular diagnostics of the virus RNA. Based on other respiratory viral infections it is estimated that the detectable viral load is present after 3-4 days of infection, which typically coincides with the first few days of the onset of symptoms. Rapid antigen test kits can reliably identify patients with high viral load during the first 7 days after the onset of symptoms, while the RT-PCR test can still detect viral RNA for an extended period of time (2-3 weeks after infection).

Please refer to the individual brochures for accuracy information.

Please get in touch with us through the Contact form indicating the type and volume of the testing kits needed.

The Camtech™ COVID-19 IgM/IgG test has been designed to minimise the likelihood of false positive test results. With regards to serological testing the FDA specifies that true negative samples should have been from patients prior to the SARS-CoV-2 outbreak (pre-pandemic samples) as RT-qPCR is not an effective way of ruling out past infections. However, If the Camtech™ IgM/IgG test gives you a positive result which is in contrast with a negative RT-qPCR result there may be several factors to consider, these include but are not limited to.

• RT-qPCR may be negative due to the lack of viral nucleotides in patients who have recovered from SARS-CoV-2, however, antibodies against the infection may persist, resulting in a positive Antibody test.


• Cross-reactivity with non- SARS-CoV-2 associated circulating antibodies (i.e. Influenza).


• The RT-qPCR result may be a false negative.


• Poor interpretation of results, potentially due to use by non-qualified medical professionals.

Positive antigen kit result: If you have a positive result it is very likely that you have the proteins from the virus that was found in your sample. The antigens are generally detectable in the specimens from the upper respiratory tract, nevertheless, clinical correlation with patient history and the necessary diagnostic information is required to determine the infection status. Positive results also do not rule out bacterial infection or cross-infections with other bacteria or viruses.

Negative antigen kit result: A negative result indicates that the antigens from SARS-CoV-2 was not present in the specimen. It also means that the viral load was below the limit of detection. The amount of antigen in a sample is known to decrease with the increase in the duration of the illness. However, a negative test should not be used as the only basis of treatment or patient management as samples collected beyond 7 days post symptom should be treated as presumptive and confirmed with a molecular assay.

Based on the 2020 December report from the European Centre for Disease Prevention and Control antigen kits validated by the UK still meet minimum performance criteria for this variant. Camtech's COVID-19 Viral Antigen Detection kit is also based on the same principles as the validated rapid tests, and currently being evaluated for its performance on the mutant strain.