Analysis of the dynamics of COVID-19, different age groups, anti-vaccine populations, and impact on reinfection

Previous studies have reported age-related differences in resistance and responsiveness to coronavirus disease 2019 (COVID-19), with younger individuals tending to have better outcomes than older individuals. Moreover, his age-targeted COVID-19 mitigation strategy reportedly significantly reduced intensive care unit (ICU) admissions and deaths.

recently scientific report In a journal paper, researchers developed a new compartmental model for estimating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and associated mortality in the United States.

study: Modeling COVID-19 transmission among US age groups, accounting for viral mutation, vaccination, and reinfection. Image credit: blvdone / Shutterstock.com

About research

In this study, investigators performed compartmental susceptibility-infection-recovery-death-vaccination-virulence (SIRDV) modeling to assess COVID-19 among children aged 12–17 years and adults aged 18–64 years. We predicted age-stratified differences in 19 severity outcomes. Aged 65 years and older, considering SARS-CoV-2 mutation, reinfection and vaccination.

To simulate intra- and inter-age-group interactions, this model used SARS-CoV-2 infections driven by virulence inferred from the population balance equation. Initially, the model was fitted for SARS-CoV-2 infection cases, deaths, and vaccinations from January 2021 to July 2021. The model was then utilized for his COVID-19 predictions beyond August 2021.

The team ran four different simulations. First, how the association between increased SARS-CoV-2 infection rates and vaccine ineffectiveness and his variant of concern (VOC) SARS-CoV-2 delta changes the dynamics of COVID-19. It was decided whether to let

Schematic representation of the SIRDV-Virulence (Susceptibility-Infection-Recovery-Death-Vaccination-Virulence) model and the overall process of the study. (a) predicts SIRDV-virulence model (Susceptibility-Infection-Recovery-Death-Vaccination-Virulence) Infection with COVID-19 In the United States, members of three age groups (children, adults, and the elderly) move into compartments (blue) at velocities influenced by parameters adjacent to the intercompartmental arrows (blue). Infected members of each age group may contribute to the growth of a single virulence parameter (orange) and infect both susceptible her SiSi and vaccinated her ViVi individuals. (b) data are fed into a compartment model to fit its parameters and used to run simulations to predict future scenarios. ) impact of COVID-19 anti/non-vaccinated proportions, and (4) impact of reinfection.

Second, the effects of varying the rate of vaccine deployment and inoculation were assessed to determine the optimal vaccination strategy to reduce SARS-CoV-2 infection and associated mortality.

Third, researchers investigated the impact of changing the anti-vaccine/non-vaccine ratio of US citizens. Fourth, the impact of including reinfection in model estimates was estimated.

Four sets of 16 parameters were obtained over four time periods. Three of his datasets were used for modeling. Weekly COVID-19 cases by age, SARS-CoV-2-related mortality by age, and SARS-CoV-2 vaccination by week.

The first period runs from January 9, 2021 to March 6, 2021, during which Alpha VOC was considered the dominant cyclical stock. The second period runs from March 6, 2021 to May 8, 2021, during which Delta VOC was the dominant cyclical stock.

Older people and adults were vaccinated in the first and second stages, but children were not vaccinated against COVID-19. Therefore, the third period is considered to be between He May 8, 2021 and He June 12, 2021, during which Alpha and Delta VOCs predominate and individuals of all ages I have been vaccinated.

In the fourth period, from 12 June 2021 to 31 July 2021, COVID-19 vaccination coverage was significantly higher in children than in the elderly and adults. Heatmaps were compared to assess vaccination priorities by age.

The long-term effects of individuals who are unable or unwilling to receive COVID-19 vaccination have been assessed using the pro-vaxxer-anti-vaxxer-infected-recovered-dead-vaccinated-virulence (PAIRDV-virulence). I was.

Survey results

A gradual decline in the number of new cases of COVID-19 and related deaths was observed during the third period. However, the proportion of Delta variant infections increased during the fourth period.

Relative SARS-CoV-2 infection rates decreased across age in the first three periods. However, the dominance of delta VOC in the fourth period led to a sharp increase in permeability.

Vaccination rates among the elderly were high in Phases 1 and 2. However, adults and children were more vaccinated in the 3rd and 4th stages than the elderly.

Recovery rates increased over time at all ages. However, increased mortality was observed among the elderly during the fourth period. Compared with the elderly, the changes in adult and child mortality were negligible over all periods.

Children contributed the most to SARS-CoV-2 viral load On the other hand, the elderly contributed the most in the second and third periods, and the adults contributed the most in the final period.

Individual time-to-time infection increased mortality during delta control. The total number of future SARS-CoV-2 infections and associated deaths, and the percentage of COVID-19 vaccinees, depended more on adults and children than on the elderly.

An increase in the anti-vaccine/non-vaccine ratio increased the virulence of SARS-CoV-2, resulting in an increase in the number of COVID-19 cases and associated deaths. Conversely, increasing the proportion of vaccinated individuals reduces COVID-19 cases and deaths.

An increase in the unvaccinated susceptible population was projected to increase COVID-19 cases and associated deaths at all ages. Moreover, some of the anti-vaccines affected adults and children more than the elderly.

An increase in the value of the reinfection parameter, which describes the proportion of recovered individuals who are likely to become reinfected, was predicted to increase the number of active SARS-CoV-2 infections and deaths. However, the increase in death toll was less significant.

For SARS-CoV-2 infection rates to stay the same and vaccines to stay the same Effectiveness (holding values ​​from the 4th period), active SARS-CoV-2 infections were estimated to peak in October 2021. In the worst-case scenario, SARS-CoV-2 infection rates doubled, and the number of active SARS-CoV-2 infections was estimated to peak almost double in December 2021. The worst-case scenario would result in a small, non-significant increase in the total number of deaths from COVID-19.

Conclusion

Current study provides estimates of the dynamics of SARS-CoV-2 transmission beyond August 2021, as well as peak times and magnitudes of transmission under different scenarios, to help improve the global preparedness of health systems There is a possibility. Furthermore, simulation results indicated that the optimal vaccination strategy is to prioritize children and adults who were shown to be more susceptible to vaccination than the elderly.