The closer the world to the plateau in new cases of coronavirus and the closer we are to the moment of lifting the mass restrictions, the more urgent the question becomes: how to prevent a new outbreak? One of the important points when planning a strategy is the need to understand how many people are infected or have already been ill.

An article published in the journal Analytical Chemistry, devoted to testing the concept of a test for antibodies to SARS-CoV-2. Scientists have found that it can help doctors track a person’s susceptibility to the disease, as well as confirm suspected cases of Covid-19, in which other methods gave a negative result..

Since coronavirus appears to be asymptomatic in many people, the number of people infected with SARS-CoV-2 at any given point in time can be much higher than the number of confirmed cases.. At the same time, asymptomatic carriers are likely to infect other people, and those who have already been ill can be immune to future outbreaks.

The basis of the test is similar to that used for home pregnancy tests - these are test strips. The technique for detecting a positive or negative result with their help is called an immunochromatographic analysis (lateral flow immunoassay - LFA). Scientists attached a viral envelope protein to a specific area on a strip of nitrocellulose, and then added human serum.

Serum flowed from one end of the strip to the other, and any anti-viral protein antibodies bind to this area on the strip. The team found antibodies against SARS-CoV-2 using a fluorescently labeled antibody. Such detection based on fluorescence is much more sensitive than some other LFAs, such as pregnancy tests, which can be seen with the naked eye..

The researchers tested a new analysis on seven serum samples from patients with Covid-19 and 12 samples from people who tested negative for coronavirus using reverse transcription polymerase chain reaction (RT-PCR) - the common diagnostic test now in use, which sometimes.

The new analysis correctly diagnosed all seven samples as positive, and also found falsity among the negative for PCR - indeed, the person who passed it had suspicious clinical symptoms. For one sample the test system needs only 10 minutes.

According to the researchers, immunoassay can be useful for confirming negative diagnoses, monitoring patient’s recovery, studying past exposures and identifying recovered people with high antibody levels as potential plasma donors..