Goldsite COVID-19 Antigen Rapid Test Kit: Home Antigen Self-Testing Sampling, Result Interpretation, and Purchase Guide

Rapid COVID-19 antigen tests (RATs) have become a common testing tool in many households—when respiratory symptoms such as fever and sore throat appear, a preliminary diagnosis can be obtained in just over ten minutes, allowing for early rest and reducing the risk of infecting family members. This article... Goldsite COVID-19 Antigen Rapid TestFor example, this explains what a rapid antigen test actually measures, how to ensure accurate nasal swab sampling, and how to interpret C-lines and T-lines.Why does a negative result not mean no infection, and why is it necessary to test again after 48 hours?And which certifications and lists should be checked when purchasing a quick test kit.

1. What does an antigen rapid test measure? How does it differ from a nucleic acid test?

依World Health Organization (WHO) Interim Guidance on Antigen TestingAntigen diagnostic testing is the collection of antigens.Upper respiratory tract sample or salivaThrough detectionViral proteins (e.g., nucleoproteins/nucleocapsid protein N)This is used to determine whether there is a COVID-19 infection; while nucleic acid amplification testing (NAAT, such as RT-PCR) detects the virus's nucleic acid (RNA).

The biggest difference between the two lies in "convenience" and "sensitivity":

In other words, the value of rapid antigen testing lies inQuick, convenient, and you can do it yourself—When you have symptoms and want to know as soon as possible whether you are infected, it can help you get a preliminary answer in ten minutes, allowing you to rest early, wear a mask, and reduce close contact with your family.

2. Goldsite rapid test kit: principle and product specifications

Goldsite's SARS-CoV-2 Antigen Kit (Colloidal Gold) uses...Lateral flow immunochromatography(lateral flow immunoassay) is a single-use in vitro diagnostic reagent used for...Qualitative detection of SARS-CoV-2 nucleocapsid (N) antigen in human nasal swab samples。

The process can be understood as follows: Place the self-collected nasal swab into an extraction tube pre-filled with solution, exposing the viral antigens. Then, drop the extracted sample into the sample well of the test strip; the sample will flow forward along the test strip. If the sample contains SARS-CoV-2 antigen, it will be detected in the test strip.Test line (T line)Display a pink or red horizontal line; andControl line (Line C)A red line will be displayed, indicating that the test program has completed normally.

依Technical statement issued by the manufacturer regarding the variant strainThe kit usesBoth antibodies target the viral nucleocapsid protein (N protein).Since the N protein is crucial for viral survival and is relatively conserved, mutant strains exhibit fewer mutations in the N protein. The manufacturer stated that the detection sensitivity for the original strain, Delta, and Omicron was consistent (LoD = 2.5 ng/mL) after testing with the recombinant N protein.

Main specifications (as per product manual)

• Sample type:Nasal swab (anterior nasal cavity)
• Detection time:Results are available in approximately 12 minutes.
• Usage:No instruments are needed; the results can be read by the naked eye. It is suitable for non-professionals to perform self-testing in non-professional environments.
• Components:One painless nasal swab, one antigen extraction tube, one tester, one instruction manual, one packaging bag, and one packaging box.
• Target audience:Self-testing for the general public;Children under 15 years of age (at least 2 years old) should be tested with adult assistance.

3. Usage steps: How to ensure accurate nasal swab sampling?

WHO specifically pointed out thatSampling is one of the most critical factors affecting the performance of respiratory sample testing.In other words, even with the same kit, the results can vary greatly depending on how well the sampling is done. The following is the general operating procedure for this type of rapid nasal swab test (…).Please refer to the instruction manual of the product you have.）：

1. Prepare:First, thoroughly clean and dry your hands. Do not open the foil pouch containing the test card before use.
2. Remove the swab:Remove the nasal stick from the packaging.Do not touch the sampling end of the swab.。
3. sampling:Gently insert the swab into one nostril (about 1.5 cm) until you feel slight resistance; apply slight pressure to keep the swab against the inner wall of the nasal cavity.Rotate 4 to 6 times for at least 15 seconds.Then, use the same swab to repeat the same steps in the other nostril.
4. Sample extraction:Place the sampled swab into the extraction tube and immerse it in the solution.At least 15 secondsRotate the swab several times and squeeze the sampling end of the swab about 3 times; when taking it out, press it against the tube wall to squeeze the liquid back into the tube, and then put the tube cap on.
5. Adding samples:Place the test card on a flat surface and open the small cap at the front of the extraction tube.Add the specified number of drops vertically (2 drops for this product).Insert the sample into the sample hole (S) of the test card. Turn on the timer.
6. Read results:Wait at room temperature for approximately 12 minutesSubsequent observation results.Results will no longer be valid after the specified time (15 minutes for this product).Don't wait until later to interpret it.
7. Aftermath:Place all testing components in a sealed bag and discard.Cannot be reusedThen clean or disinfect your hands again.

4. Interpretation of Results: Positive, Negative, and Invalid

There are two places to look at on the test card:Line C (Control Line)與 T-line (test line)。

The manufacturer pointed out that if line C does not appear, it means...The test program failed to complete normally.Therefore, this result cannot be used. Furthermore, the product manual also reminds users that:A positive result does not rule out the possibility of concurrent bacterial or other viral infections.；A negative result should be considered a hypothetical result.If necessary, molecular testing can be used for confirmation, but it should not be the sole basis for treatment decisions.

5. Why do I need to wait 48 hours after a negative result before testing again?

This is a point that many people overlook, but it is quite important.Frequently Asked Questions about Home Rapid Testing by the U.S. Food and Drug Administration (FDA)The accuracy of rapid antigen testsBelowMolecular testing "may not detect the virus in the early stages of infection or in asymptomatic individuals," thereforeRegardless of whether there are symptoms, a second test is recommended if the first test is negative.：

• People with COVID-19 symptoms:After the first negative result,Test again after 48 hours.(At least 2 times in total).
• Those without symptoms:After the first negative result, test a second time after 48 hours. If the result is still negative, test a third time after another 48 hours.At least 3 times in total）。
• He had contact with a confirmed case but had no symptoms:suggestionWait at least 5 days after contact before testing.Testing too early may be inaccurate.

The FDA also mentioned that ifAny timeA positive test result should be considered a strong indication of infection, and should be handled according to local guidelines. For high-risk individuals, or those visiting the elderly or those with weakened immune systems, it is recommended to consult a doctor beforehand regarding testing arrangements.

6. Certifications and Lists: What to Check When Purchasing a Quick Testing Kit

There are numerous brands of quick testing kits on the market, varying in price and with a wide array of "certifications" listed on their packaging. Rather than relying solely on the numbers on the packaging, it's more practical to understand...Where to check。

(1) The CE mark depends on "which type" it is.

CE certification is a compliance mark for manufacturers entering the EU market. It is worth noting that:Not all CE markings are the same.Some in vitro diagnostic products (such as COVID-19 antigen reagents for self-testing) require approval.EU-recognized Notified BodyAfter review and obtaining the certificate, the organization's number will be printed on the packaging, for example... CE 1434(1434 is the Notified Body number, corresponding to the Polish PCBC); while some products only belong to...Manufacturer's self-declaration of conformityNo third-party review is required. The level of review differs between the two.

(2) The lists of countries during the pandemic have mostly been taken over by the new system.

Between 2021 and 2022, several regions established temporary rapid testing lists or assessment programs, such as Germany's BfArM list, France's ANSM self-testing registry, registrations in Italy and Spain, and the UK's DHSC phased assessment. These all fall under...Pandemic Period SystemMany of these systems have since ceased updating or been replaced by existing ones (for example, the UK switched to the CTDA system for approvals in the second half of 2021). Therefore, the statement on the packaging that "approved by [country name] on [list]" should be understood as...He was on that list back then.This does not mean that the same system is still in effect at present.

(3) Three easily overlooked purchasing points

• Confirm user category:Similarly, some COVID-19 antigen tests are only for healthcare professionals (with higher sampling requirements), while the general public should choose those clearly labeled..."Self-testing" / "Personal use"Products.
• Pay attention to the expiration date and batch number:Before use, check that the packaging is intact, the label is clear, and the product is not expired.Do not use expired, damaged, or illegible reagent kits.。
• Do not mix components across different boxes:Swabs, extracts, and test cards from different batches should not be used interchangeably.

7. Precautions for use and storage methods

According to FDA safety advisories, home rapid testing kits are safe when used according to instructions, but...Improper use may cause injury.—Especially small vials of liquids like extracts, which may containSodium azideThese chemicals may cause discomfort if swallowed, or if they come into contact with the skin or eyes.

• Do not drink the extract.If accidentally ingested, seek medical attention immediately; if splashed on skin or in eyes, rinse immediately with water and seek medical attention if the condition is serious.
• Keep out of reach of children and pets— This should be done both before and after use.
• For in vitro diagnostic purposes onlyIt is not edible;Do not ingest the desiccant inside the packaging.。
• Do not reuse.Do not exchange or mix components from different batches of the kit, including the reagent kit, extraction tubes, or swabs.
• Avoid touching the tip of the swab when handling it.It is recommended to wear gloves during sampling and testing.

Storage conditions

• According to FDA guidelines, the typical operating environment for home rapid testing is as follows:Approximately 15 to 30°CIf the reagent kit has been exposed to extremely cold or hot environments (e.g., just delivered from outdoors), it is recommended to first...Leave in the original packaging at room temperature for at least 2 hours.Reopen and use.
• Prolonged exposure to high temperatures may affect performance; if the test line does not appear at the correct time and location, the results may be inaccurate.The test needs to be repeated using a new reagent kit.。
• According to the product instructions, it can generally be stored at room temperature (approximately 2 to 30°C), avoiding direct sunlight and moisture.

8. What to do after getting the test results?

依Centre for Health ProtectionCurrent health advice for people who test positive for COVID-19:

• High-risk individualsFor example, people with suppressed immunity, older age, or pre-existing health conditions, orObvious symptoms appearedPeople who shouldSeek medical attention as soon as possible。
• Those with symptomsYou should stay home and rest, and avoid going out;AsymptomaticStudents are free to go out or to work. Students with symptoms should not return to school.
• Infected peopleThe first five days after a positive testWear a close-fitting surgical mask, KF94/KN95 mask or respirator at all times, avoid contact with high-risk individuals, minimize contact with others who are not wearing masks (such as dining at the same table), and do not go to crowded places or participate in large gatherings.
• You should always pay attention to your physical condition.If symptoms worsen, seek medical attention immediately.Also, try to keep windows open to maintain indoor air circulation and frequently clean and disinfect shared household items.

The Centre for Health Protection also pointed out thatPeople aged 60 and over, or those with high blood pressure, heart or lung problems, diabetes, obesity, cancer, or who are pregnant.Individuals with certain symptoms or a positive rapid test result are at greater risk of developing serious conditions. These individuals should not self-monitor and should seek medical attention as soon as possible if they develop symptoms or a positive rapid test result.

9. Alternatives to COVID-19: Combined rapid test for influenza/RSV

The initial symptoms of COVID-19, influenza, and RSV (respiratory syncytial virus) are quite similar, making them difficult to distinguish based on symptoms alone. Therefore, similar cases have emerged in recent years.Rapid antigen test combining COVID-19 with influenza A/B and RSV—In the list already compiled by the Department of Health’s Medical Devices Division, this type of product is classified as “Combined rapid antigen test for COVID-19 and other pathogens”, and will also be labeled as “for personal use” or “for healthcare professionals only”.

The practical significance of merging rapid tests lies inTriage and Early Processing:according toUS CDCInfluenza antiviral drugs belong toPrescription drugs,existFor best results, start taking the medication 1 to 2 days after the onset of symptoms.Pregnant women, people with asthma and chronic lung disease, diabetes, and heart disease are considered higher-risk individuals and should seek medical attention as soon as flu symptoms appear.Seek medical attention as soon as possibleIn other words, if a rapid test can distinguish between COVID-19 and the flu, it can help you decide more quickly whether you need to seek medical attention.

10. Frequently Asked Questions (FAQ)

11. Goldsite Antigen Rapid Test Kit Product Information

12. Sources of information

This article compiles information on the use of home antigen rapid tests and is for reference only.This does not constitute diagnosis, treatment, or prescription advice, nor can it replace professional medical advice.Rapid antigen tests are supplementary screening tools; results must be considered in conjunction with symptoms, exposure history, and assessment by healthcare professionals. If symptoms persist or worsen, or if you are a high-risk individual, please seek medical attention immediately. Product specifications, certification status, and regional lists may be updated over time; please refer to current official information and product instructions before purchasing and using the product.

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