A look at the various virus sampling swabs you didn't know about
The following types of swabs are commonly used.
Medical swabs
The most common wood-handled cotton swabs, the advantage is cheap and easy to obtain, the disadvantage is that may inhibit the PCR reaction (the U.S. CDC used a "may", so I can not think of its sister), wooden handle is not easy to break, not suitable for virus sampling.
Artificial silk swabs
Polyester, polyester or rayon head with a plastic or aluminum handle, swabs produced by winding, suitable for virology test specimen collection.
Flocked Swabs
Made from nylon fibers by spray technology for better water absorption and release, they are now widely used for sampling respiratory viruses such as Neocon.
Printed Swabs
How in the end this thing I do not know, happened to look up everyone to understand it.
Third, the evaluation of sampling swabs
About the sampling swab evaluation index I from the water absorption, virus release rate and several other indicators to evaluate, because I did not find the relevant standards so the assessment may not be comprehensive and scientific, I hope professionals to criticize the correction. In view of the factors of intellectual property rights this article does not disclose all the data, please understand.
Water absorption
Water absorption reflects the ability of different material swabs to absorb water, usually the stronger the ability to absorb water, the better. Soak the swabs of different materials in the same volume of liquid, and then take out the swabs to calculate the water absorption of each swab.
Test results: water absorption Cotton swabs > flocking > rayon
Discussion: Since the size of the swab head of the three swabs is different, the head of the cotton swab is larger so the water absorption is also larger, it would be more accurate to evaluate under the same size of the swab head, but each manufacturer produced is of different sizes, so this experiment is also representative.
Virus release rate
Virus release rate reflects the release efficiency of different material swabs after adsorption of virus, the higher the virus release rate, the more viruses obtained by sampling. Considering the diversity of clinical sampling, I considered the viral release rate in both cases when the swab was completely wet and when the swab was dry after sampling.
Wet swab virus release rate
This test was done together with the water absorption test. After adding an equal amount of virus to the same volume of PBS, three swabs were soaked and placed in another equal volume of PBS, and then the virus content in the solution was detected using qPCR.
Test results: The virus release rate of wet swabs was slightly better for cotton swabs than for flocking and significantly better than for rayon
Discussion: Since the water absorption of cotton swab is 1.5 times that of flock, the release result on cotton swab is slightly better than flock, and if the virus release rate is calculated at the same water absorption, flock has the highest virus release rate.
Summarization.
Flocked swabs are better than other materials in this test in terms of virus release rate and stability; rayon is worse in this test, I do not know whether it is related to the swabs selected in this test, and the follow-up is to be further evaluated; cotton swabs have the highest water absorption but the release rate is not as good as flocked, and cotton swabs have the most virus degradation at 37 degrees without the presence of protective fluid may be related to the CDC mentioned "they may contain substances that inactivate some viruses and inhibit PCR testing." related, for the time being, cotton swabs were not found to contain ingredients that inhibit PCR reactions.
