The Limited Times

Now you can see non-English news...

The testing contractor stated that nasal swab sampling needs to be 3cm deep. It is recommended to collect nasopharyngeal samples at the airport to prevent leakage

2021-05-07T19:28:10.375Z

BGI was previously revealed to be involved in a number of "false positive" cases. Four confirmed cases of the variant virus "leaked" during the hotel quarantine but did not test positive and walked into the community. BGI was also responsible for testing. Hong Kong Molecule



Social News

Written by: Zhang Jiamin

2021-05-07 00:00

Last update date: 2021-05-07 00:00

BGI was previously revealed to be involved in a number of "false positive" cases. Four confirmed cases of the variant virus "leaked" during the hotel quarantine but did not test positive and walked into the community. BGI was also responsible for testing.

The Hong Kong Center for Molecular Pathology recently conducted a study on the accuracy of the test and found that if a nasal swab is used for sampling, the depth and residence time both affect the accuracy.

He pointed out that, according to the central standard, the swab must be taken at least 3 cm deep into the nasal cavity and stay for 5 seconds or more.

As for the "leakage" of confirmed cases of the variant virus, he pointed out that the government may consider taking nasopharyngeal swabs for people entering the country at the airport, and quality control should be carried out.

Huang Libao, director of the Hong Kong Center for Molecular Pathology, pointed out that the depth and residence time of the swabs will affect the accuracy of the test.

(Photo by Zhang Jiamin)

The Hong Kong Molecular Pathology Laboratory recently used nasal swabs for 46 employees of the center to take samples at different depths and residence times to test the correlation between each situation and the accuracy of the test.

Among them, if the swab was used to penetrate the nasal cavity for 1 cm and stay for 3 seconds, the highest CT value was obtained, with an average value of 36.59, which means that the amount of human genes available for testing is the least; there are 7 samples without any CT value.

If the swab is taken 2 cm deep into the nasal cavity and stayed for 5 seconds, the average CT value is 30.55, which is the lowest value in the test, and all samples can obtain CT values.

The higher the sampling, the higher the accuracy

As for the swab to penetrate the nasal cavity for 1 cm and stay for 5 seconds, the average CT value is 35.4; while for the nasal cavity for 2 cm and stay for 3 seconds, the average CT value is 31.03.

Huang Libao, director of the Hong Kong Center for Molecular Pathology, pointed out that the study found that the depth of the swab and the length of stay affect the accuracy of the test.

According to the standards of the Hong Kong Molecular Pathology Laboratory, he pointed out that the swab must be taken into the nasal cavity at least 3 cm and stay for at least 5 seconds; and if the CT value of the sample is 30 to 35, the center also needs to conduct a review of the sample.

The brush head of the swab is 2 cm, and he said that the sample is at least 3 cm deep into the nasal cavity.

(Photo by Zhang Jiamin)

As for some experts' earlier questioning that if 30 samples are taken every hour, that is, one sample is taken every 2 minutes, it is easy to make mistakes. Huang Libao pointed out that the detection accuracy has nothing to do with the length of the sampling time. It’s reasonable, and the guidelines are 10 to 15 seconds.” He pointed out that there is no prescribed residence time for throat sampling, but he believes that even with the two sampling methods, 2 minutes is definitely enough to obtain a sample for testing.

The flocked swab used by the Hong Kong Molecular Pathology Laboratory.

(Photo by Zhang Jiamin)

Larger airport space allows nasopharyngeal swab samples to be taken, lower risk of infection

Regarding the “leakage” of a variant virus that has flowed out of the community, he pointed out that nasopharyngeal swab sampling is the most accurate sampling method. It is recommended that the government consider using nasopharyngeal swab sampling at the airport, because the airport has a large space and the risk of infection Lower.

However, he pointed out that it is difficult to quarantine hotels with nasopharyngeal swabs. Due to poor air circulation and carpets and other items that are difficult to clean, patients may leave the virus on the objects during sampling, which poses a greater risk of transmission.

He pointed out that the sampling accuracy of flocked swabs is higher than that of cotton swabs, but the cost is relatively high, and the price difference between the two is at least half.

▼At about midnight on May 5th, residents of Block N2 of Kornhill were evacuated for quarantine▼

▼A temporary testing station will be set up in Discovery Park, Tsuen Wan on May 5▼

+7

+7

+7

Variant virus | BGI, a patient accused of a variant virus: false negatives are not necessarily related to sampling

Variant virus | 4 patients were quarantined 21 days after the community confirmed hotel testing by BGI

BGI laboratory samples were contaminated in 26 cases of false positives, Cai Jiyou kindergarten teachers were not diagnosed

BGI's suspected sampling leaks Yuan Guoyong advocates sampling of negative samples to determine the quality of outsourcing testing

01News

National genetic testing for new coronary pneumonia

Source: hk1

All news articles on 2021-05-07

You may like

Trends 24h

Latest

© Communities 2019 - Privacy