Improving the Method for Simulating the Evolution of SAR-CoV-2 in the Form of Hybrid SIR Models for Predicting New COVID-19 Waves

Methods for computational study of the epidemic process resumed in 2024 due to the new SAR-CoV-2 branch and the Pirola wave are discussed. The epidemic modeling technique based on various compartmental SIR systems with the reflection of transitions according to the scheme between the epidemic statuses of individuals is compared with the analysis of the rapidly emerging Pirola wave of the spreading updated coronavirus. The inclusion of physical oscillators of second-order nonlinear equations into a SIR system has been considered a way to modify the epidemic models, but their complex modes and randomization do not correspond to the epidemic course. To simulate changes in the trends in nonlinear effects of the biophysical processes experiencing pulsating variations caused by the evolution of the virus, approaches based on modification of the technical physics models, e.g., the Korteweg‒de Vries equation, have been used. The results of the computational experiments with the model cannot be considered as a sufficient result. The consistency of the computations has not been justified. The author has proposed to expand the structure to 12 statuses in relation to COVID. It is shown that expanding a set of possible statuses in a SIR system of differential equations that describe transitions between statuses of population members characteristic of COVID does not lead to the appearance of damped oscillatory modes interrupted by a new outbreak. In the field of forecasting the spread of new infections, not all factors will be established in the near future. Classical epidemic models, even with a fundamental extension of the linear SIR framework, are not suitable for the aspects of nonlinearity and pulse generation of COVID infection chains unless they include infected and immune thresholds and a lag factor. It has been substantiated that the method for expanding SIR systems does not have prognostic prospects. It is shown that the emergence of new branches of the Omicron BA strains in 2021 and JN in 2023 led to the qualitative transformation of the shape of oscillations and not just the peak amplitude. The interval between a peak and minimum has increased, i.e., not only one of the SIR model parameters has changed. According to the analysis of our data, in the winter and spring of 2024, the transition to the third mode of oscillations of infection cases during the pandemic period is implemented. In several countries, antiepidemic restrictions were completely removed in the spring of 2023, which allowed us, based on the course of new waves in 2024, to analyze the effect of the mask mandate and lockdown factors. It has been confirmed that these strict measures did not change the epidemic situation, in which the transmissibility rate exceeds a critical threshold value. A scenario for the development of the epidemic models based on hybrid predicatively redefined systems of equations is proposed, which takes into account the pulsed evolution of the coronavirus according to the spiral principle. For transitions of forms of oscillatory epidemic modes, a predicative redefinition of equations with the threshold regulation delay and dampers has been used.