COVID-19 Rapid Antigen Test Kit FAQs

What is antigen?
An antigen is a molecule or molecular structure present in a pathogen that, when detected in the human body, can trigger an immune response. Common antigens include simple molecules such as carbohydrates, fats, hormones, and larger molecules including polysaccharides, phospholipids, nucleic acids, and proteins.
How does rapid antigen test work?
Antigens are present in SARS-CoV-2 viruses, which can often be found in the respiratory tract during early-stage infections (2-3 days). These antigens, when detected, can serve as markers for disease exposure.
What type of specimen does it use?
The test uses nasal swab samples, which are collected from the nostrils.
How to use? Is it complicated?
  1. Collect anterior nasal swab specimen
  2. Stir the swab into the buffer solution
  3. Drop 3 drops of the buffer solution into the test device
  4. Read the results promptly in 20 minutes (results after 25 minutes should not be used)
INDICAID®COVID-19 Rapid Antigen Test Instruction Video
Does the sample collection process cause any discomfort?
The sample collection process is very simple. The swab only needs to be inserted about 1 inch into the nostrils (and not as far as the nasal cavity), which will not cause any pain or discomfort to the user.
How to interpret the results?
Negative: A line appears in the region (C)
Positive: A line appears in regions (C) and (T)
Invalid Result: No line appears in the region (C)


Positive Result: Please contact your doctor and follow the Department of Health's instructions regarding the positive cases arrangement.
Negative Result: Regular testing (at least once every week) is recommended. If you have had contact with a known or suspected COVID-19 case, you are recommended to take a PCR test.

Is the result accurate?
The accuracy of COVID-19 Antigen Tests is measured under two metrics:
  • Sensitivity: Measures the ability to correctly identify positive patient samples. If a test kit has a high sensitivity, it means that the kit has a high positive percentage agreement and a low false negative rate
  • Specificity: Measures the ability to correctly identify negative patient samples. If a test kit has a high specificity, it means that the kit has a high negative percentage agreement and a low false positive rate
INDICAID®'s overall sensitivity and specificity is 96% and 99% respectively, and is able to detect the presence of certain COVID-19 variants.
Has INDICAID® gone through any clinical validation?
INDICAID® has passed extensive clinical validation. In Hong Kong Government’s Community Testing Scheme, INDICAID® has been used as part of the dual-track testing scheme along with COVID-19 PCR tests. As of January 2021, after the completion of 22994 clinical tests, it has been shown to reach accuracy comparable to PCR tests. This is the world's largest clinical study for a product of its kind.
Are nasal swab samples more accurate?
COVID-19 is mainly airborne, and will first pass through the nasal cavity before entering the upper respiratory tract. Medical research shows a relatively high virus content can be found in nasal swab samples. Using nasal swab samples for COVID-19 testing is done internationally. Compared to other sampling methods, the use of nasal swab samples can guarantee a higher test sensitivity.
The test is suitable for:
  • People with relevant epidemiological or contact history with those who are suspected or have been infected with COVID-19.
  • People who have recently travelled to communities, shopping malls or other places related to a COVID-19 outbreak.
  • Frontline staff who are in frequent contact with customers.
  • People who frequently use mass public transportation.
  • People who attend large gatherings, visit communities or venues with a high population density.
How often should I conduct the test?
Compared to traditional PCR test, regular and frequent testing can better help prevent the spread of COVID-19. Below is a recommended testing frequency:
  • For low-risk populations, such as healthy and young individuals without frequent contact with crowds, it is recommended to test once per week
  • For moderate-risk populations, such as staff in small and medium enterprises, it is recommended to test twice per week
  • For high-risk populations, such as those who work in a dense and crowded environment or with the elderly, it is recommended to test every other day
Is an empty stomach required for the test?
No. The test can be done at anytime.
Supplementary Information on Virus Variants
The Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2), which caused the COVID-19 pandemic outbreak, is prone to mutation, and to producing mutant viruses (variants, variants), which may be caused by mutations of key viral proteins. Many variations of the virus have been developed and are being spread throughout the world. The World Health Organization defines them as: Variant of Concern - VOC - and Variant of Interest - VOI.

1. Variants of Concerns (VOC)

  • Virus mutations are a natural random process. A virus variant's level of concern depends on its contagiousness, morbidity, mortality, and potential for evading detection, immunization, and treatment. In accordance with recommendations of the World Health Organization, various viruses that have caused concern in many parts of the world were first discovered in the United Kingdom, South Africa, Brazil, and India, and are represented by the Greek letters Alpha, Beta, Gamma, Delta, and Omicron.
  • Alpha variant virus: Alpha was first confirmed in September 2020. It is approximately 50 % more infectious than the original SARS-CoV-2 strain and is more serious and fatal. Alpha can, however, be neutralized by therapeutic monoclonal antibodies, antibodies produced after vaccination, or antibodies produced after recovery from COVID-19 infection, indicating a reduction in the risk of infection or reinfection following vaccination, as well as regular testing of variant viruses, ensuring that variant viruses are less likely to spread.
  • Beta variant virus: Beta was confirmed in May 2020 and classified as a variant strain of high concern (VOC) in December of that year. Beta is more infectious and reduces the effectiveness of monoclonal antibody treatments and vaccines. Despite the reduction in the neutralizing effect of recovered serum, reinfection after recovery from COVID-19 infection is still possible.
  • Gamma variant virus: Gamma was confirmed in Brazil in November 2020. Gamma has the ability to evade the neutralizing effects of antibodies (monoclonal therapeutic antibodies and antibodies produced by infection with SARS-CoV-2 or vaccination), thus greatly increasing the risk of secondary infection and infection where the vaccine does not work.
  • Delta variant virus: Delta was confirmed in India in October 2020, and it was also responsible for the heaviest casualties in the second wave of the epidemic in India. Although the general public has been vaccinated in the UK, lockdown measures were repeatedly extended because of Delta. Since Delta strains are more contagious and can reduce the effectiveness of antibodies produced by infections and vaccines, they are considered the most detrimental variant strains in the world.
  • Omicron variant virus: Omicron was first confirmed in South Africa in November 2021. Its transmission speed is 2-4 times faster than Delta, causing the virus to spread rapidly throughout the world. Omicron, however, causes a lower risk of severe illness and hospitalization compared to the other variants.
2. Variants of Interest (VOI)
Including: Kappa (B.1.617 Type), Epsilon (B1.427 Type and B.1429 Type), Lambda (C.37 Type) and Mu (B.1.621 Type)

Supplementary Information on Virus Variants
The Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2), which caused the COVID-19 pandemic outbreak, is prone to mutation, and to producing mutant viruses (variants, variants), which may be caused by mutations of key viral proteins. Many variations of the virus have been developed and are being spread throughout the world. The World Health Organization defines them as: Variant of Concern - VOC - and Variant of Interest - VOI.

1. Variants of Concerns (VOC)

  • Virus mutations are a natural random process. A virus variant's level of concern depends on its contagiousness, morbidity, mortality, and potential for evading detection, immunization, and treatment. In accordance with recommendations of the World Health Organization, various viruses that have caused concern in many parts of the world were first discovered in the United Kingdom, South Africa, Brazil, and India, and are represented by the Greek letters Alpha, Beta, Gamma, Delta, and Omicron.
  • Alpha variant virus: Alpha was first confirmed in September 2020. It is approximately 50 % more infectious than the original SARS-CoV-2 strain and is more serious and fatal. Alpha can, however, be neutralized by therapeutic monoclonal antibodies, antibodies produced after vaccination, or antibodies produced after recovery from COVID-19 infection, indicating a reduction in the risk of infection or reinfection following vaccination, as well as regular testing of variant viruses, ensuring that variant viruses are less likely to spread.
  • Beta variant virus: Beta was confirmed in May 2020 and classified as a variant strain of high concern (VOC) in December of that year. Beta is more infectious and reduces the effectiveness of monoclonal antibody treatments and vaccines. Despite the reduction in the neutralizing effect of recovered serum, reinfection after recovery from COVID-19 infection is still possible.
  • Gamma variant virus: Gamma was confirmed in Brazil in November 2020. Gamma has the ability to evade the neutralizing effects of antibodies (monoclonal therapeutic antibodies and antibodies produced by infection with SARS-CoV-2 or vaccination), thus greatly increasing the risk of secondary infection and infection where the vaccine does not work.
  • Delta variant virus: Delta was confirmed in India in October 2020, and it was also responsible for the heaviest casualties in the second wave of the epidemic in India. Although the general public has been vaccinated in the UK, lockdown measures were repeatedly extended because of Delta. Since Delta strains are more contagious and can reduce the effectiveness of antibodies produced by infections and vaccines, they are considered the most detrimental variant strains in the world.
  • Omicron variant virus: Omicron was first confirmed in South Africa in November 2021. Its transmission speed is 2-4 times faster than Delta, causing the virus to spread rapidly throughout the world. Omicron, however, causes a lower risk of severe illness and hospitalization compared to the other variants.
2. Variants of Interest (VOI)
Including: Kappa (B.1.617 Type), Epsilon (B1.427 Type and B.1429 Type), Lambda (C.37 Type) and Mu (B.1.621 Type)