The solid-phase immunocapture with antibodies is an important tool used in immunology studies, but conventional polystyrene plates are prone to deformation during thermal cycling and cross-contamination of samples, which reduces accuracy and reproducibility, when molecular genetic testing methods are included in the study. The development of alternative solutions, such as modified polystyrene-coated polypropylene tubes, makes it possible to eliminate these limitations. The study aimed to create a new approach to SARS-CoV-2 immunocapture involving the use of modified test tubes and to assess its efficacy. Monoclonal antibodies P2C5 and R107, as well as inactivated strains GК2020/1 (Wuhan) and hCoV-19/Russia/MOW-PMVL-51/2021 (Omicron) were used for analysis. Immobilization of antibodies, sorption of viral particles, and RNA extraction were accomplished using modified test tubes, standard plates, and uncoated test tubes. The key findings showed that the polystyrene-coated modified test tubes ensured better immunocapture compared to the plates (p < 0.0001), especially when using the P2C5 antibody effective against various SARS-CoV-2 lineages, including Omicron. The R107 antibody showed limited specificity, not exceeding that of the control group with bovine serum albumin. The cross-contamination analysis revealed contamination of 14 samples out of 288 in the plates, while no contamination of samples was reported for modified test tubes. Thus, modified test tubes used for high-precision molecular testing have some advantages, since these decrease the risk of cross-contamination and improve immunocapture efficacy.