New COVID antibody test device can initiate comprehensive immune screening

The slight increase in COVID cases these days is driven by many different factors – in large part the emergence of highly contagious variants such as omicron and a decrease in rules for concealment and social distancing, but also a general decline in immunity for those who are vaccinated, which is no surprise. Antibodies naturally decrease, whether caused by infection or vaccination, over a period of two months (or faster depending on a person’s age and health). Since COVID threatens to be a frequent guest in the house, scientists are beginning to develop new ways to quickly and easily assess the state of immunity.

In order to achieve this goal, researchers in Hong Kong have developed a device that allows anyone to see their antibody levels right after vaccination. The device is newly detailed Friday paper published in the magazine science progress, on a par with conventional coronavirus antibody testing platforms. It can be used as a better way to perform a comprehensive COVID immunity screening, to monitor a person’s post-vaccine immune status, or even to customize vaccine doses according to an individual’s immune needs.

The most accurate antibody test currently available requires blood samples to be analyzed in a laboratory. There are more convenient home options that test your secretions from your spit or nose. The problem with these accessible kits is that they can only give you a yes or no and don’t take into account the level of antibodies that are tracking in your body, Ting-Hsuan Chen, a biomedical engineer at City University of Hong Kong, told the study’s lead author. The Daily Beast.

The new device, which can fit in the palm of your hand, consists of a small transparent chip that holds two types of microparticles, tiny channels, and a small window to see the end result. One of the microparticles is magnetic and coated with the protein spike of the virus. The other is made of a compound called polystyrene and studded with antibodies that attract COVID antibodies, which normally target the spike protein.

Users only need to provide a few small drops of blood plasma from a finger prick. If the COVID antibodies are present, they will stick to the polystyrene microparticles, which in turn will stick to the magnetic microparticles. The magnetically connected microparticles are separated from the single particles and collected in a small viewing window, called a particle bridging. A small bar etched next to the dam corresponds to the concentration of antibodies present in nanograms per milliliter.

Chen and his team tested the device on 91 people who had received the second dose of the vaccine a few weeks earlier. The team found that antibody levels were highest for those who received the mRNA vaccine. But for everyone else, antibody levels dropped significantly after 45 days. These results were comparable to antibody tests performed in the lab and were better at detecting lower levels of antibodies than the at-home detection kits, which hardly scored positive.

It is important to note that although antibody levels are naturally low, this does not mean that you lose the ability to make antibodies. After a vaccination or infection, your body creates a memory of the antigen that it learns to target, and if it appears again, your immune system can launch a quick attack.

However, Chen said your body still takes time to reactivate that memory and recreate the necessary antibodies. In this case, the new test device could come in handy: During an outbreak, health agencies, doctors or the people themselves can monitor antibody levels and see who among those previously vaccinated do not have a strong enough response and may need a booster dose. This may lead to more personalized vaccine doses based either on age – older adults tend not to develop strong immune responses after vaccination – or health status, such as if you are immunocompromised.

Chen and his team are still working on making the device more accessible, such as making it able to detect antibodies in samples such as spit or nasal secretions, making the device possible for home use.

“Our vision is to provide a device that is as simple as a rapid test but also provides as good accuracy as [conventional antibody testing]Chen said. “I usually make an analogy to a mercury thermometer. It is a device that you can see and measure temperature accurately without any equipment and everyone can use it. We hope our device will be that way, easy to use and everyone can read without any confusion to get the results they need.”

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