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 eligible 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.
Is a test report provided?
INDICAID labTM provides INDICAID® COVID-19 Rapid Antigen Test with report (able to detect the presence of certain COVID-19 variants). Click to learn more.
Supplementary Information on Virus Variants
引發2019冠狀病毒病的嚴重急性呼吸綜合徵冠狀病毒 (SARS-CoV-2) 容易發生突變,而產生變種病毒(變種、變體),關鍵病毒蛋白的突變即可能意味著其出現,目前已有多個變種病毒在世界許多地區形成並傳播。按世界衛生組織定義分為:高關注變異株 (Variant of Concern - VOC) 及需留意變異株 (Variant of Interest - VOI)。

1. 高關注變異株

  • 病毒的變異是一個自然隨機過程。病毒變種引發關切的程度取決於其導致的傳染性、發病率、死亡率,及逃避檢測、免疫與治療的風險。目前在世界多地引發關切的變種病毒最早發現於英國、南非、巴西及印度,依世界衛生組織建議分別由希臘字母 Alpha、Beta、Gamma、Delta、Omicron 標記。
  • Alpha 變種病毒:Alpha 最早在2020年9月被確認。其傳染力比原始的 SARS-CoV-2 病毒株高出約50%,而且能造成更多重症及更高的致命率。但 Alpha 可以被治療性單株抗體、接種疫苗後產生的抗體或感染 COVID-19 康復後所產生的抗體中和,這表明感染或接種疫苗後再次感染的風險都會降低,定期進行變種病毒檢測亦有助降低傳播變種病毒的風險。
  • Beta 變種病毒:Beta 在2020年5月被確認,且在同年12月被歸類為高關注變異毒株 (VOC)。Beta 具有更高的傳染力,並且會降低單株抗體治療和疫苗的效力。雖然對於癒後血清所產生的中和作用已降低,但感染 COVID-19 康復後仍有可能再次被感染。
  • Gamma 變種病毒:Gamma 在2020年11月於巴西被確認。Gamma 有能力避開抗體(單株治療抗體及感染 SARS-CoV-2 或接種疫苗所產生的抗體)產生的中和作用,因此會使二次感染及疫苗失效的感染風險大大提高。
  • Delta變種病毒:Delta 在2020年10月於印度被確認,亦是在印度造成第二波疫情死傷最慘重的罪魁禍首。即使英國普遍群眾已完成接種疫苗,但最終還是因為 Delta 而被迫一再延長封城管制措施。Delta 的傳染力更強且能降低因感染和疫苗所產生的抗體效力,因而被認為是全球最棘手的變種病毒株。
  • Omicron 變種病毒:Omicron 在2021年11月首次於南非被發現,其比 Delta 還要高速2-4倍的傳播速度使病毒迅速蔓延至全球。不過,暫停 Omicron 導致重症及住院的風險較其他變種病毒低。
2. 需留意變異株
包括:Kappa (B.1.617.1譜系)、Epsilon (B.1.427譜系及B.1.429譜系)、Lambda (C.37譜系)和 Mu (B.1.621譜系)。

Increasing the self-immunity of the population by increasing vaccine coverage remains a top priority for countries around the world. Usually, it is also necessary to develop the habit of wearing a mask, washing hands frequently, regular work and rest, moderate exercise, and regular rapid testing and mutant virus detection to keep yourself away from the harm of Enhancing vaccine coverage and achieving herd immunity has become a major worldwide belief. It is still of paramount importance to maintain a habit to wear a face mask, wash your hands frequently, keep a regular routine and exercise, as well as get tested regularly, so that we can keep ourselves away from viruses.