Individuals under the age of 65 may be the main driver of COVID-19 in West Africa

In a recent study posted on medRxiv* Preprint server, researchers evaluated the impact of age composition and vaccine prioritization on coronavirus disease 2019 (COVID-19) in West Africa (WA).

The COVID-19 pandemic is negatively impacting countries in all parts of the world. The African Continent has witnessed less catastrophic impact than other regions. Timely implementation of non-pharmaceutical interventions (NPIs) such as demographic distribution, epidemiological disparities, low detection rates, and social distance, quarantine / isolation of suspicious / confirmed cases, travel bans, etc. ..

Given the demographics and socio-economic structure of Washington countries, drug interventions such as antiviral drugs and vaccines are important to control the infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This is the preferred strategy. The mathematical model helped provide comprehensive insights into COVID-19 dynamics and helped inform various policies and interventions.

Research and findings

In this study, researchers developed a mathematical framework to explain age structure and vaccination to estimate the contribution of older and younger people to the incidence of COVID-19 in WA. The authors have developed three compartmentalized models of SARS-CoV-2 infectious dynamics in WA.

The first model (basic model) was based on an extended Kermack-Mckenderick type framework, classifying the population into nine different classes based on disease and vaccination status. Confirmed infectious cases, hospitalization, and recovery.

Model 2 is an extension of the basic model, inoculating the population (N)_v) And non-vaccinated (N)_{u u})cohort. These two cohorts have been further subdivided as in the basic model. The third model (Model 3) was an integrated / hybrid model. Model 3 was obtained by extending Model 2 to explain the age structure. Two age groups have been defined based on the risk of COVID-19. The first group consisted of individuals under the age of 65 (adults-youth) and the second group consisted of people over the age of 65 (elderly).

Some parameters of all three models are available in the literature, others are unknown and estimated by adapting the corresponding model to daily COVID-19 case data from 16 Washington states. I did. A simplified base model version without vaccination was adapted to the pre-vaccination period data and integrated the entire COVID-19 data from February 28, 2020 to May 24, 2022. Model fitting and parameter estimation were performed using non-linear minimums. -Square algorithm.

The research team performed a global uncertainty and sensitivity analysis using Latin HyperCube Sampling (LHS) and Partial Rank Correlation Coefficient (PRCC). They noted that community infection and recovery rate fluctuations in asymptomatic infected individuals, and detection rates in symptomatic infected individuals, produced the highest uncertainty in peak COVID-19 cases of WA.

This indicates that asymptomatic infectious subjects, especially those under the age of 65, are the primary driver of COVID-19 in Washington State. The model was then simulated to analyze control measures, vaccination, mitigation of control measures, and the impact of the new SARS-CoV-2 variant. Simulation results for Model 1 show that at least 84% of the WA population had control reproduction numbers (R)._cModel 2 (73%) and Model 3 (68%) required lower vaccination rates.

Researchers have reported reducing R_c Unless the daily vaccination rate was very high, it was not possible to vaccinate only young people or adults, even with a 20% increase in mask use. Nevertheless, if both young and old are vaccinated at specific target rates, the disease can be contained.

Vaccination seemed to significantly affect the peak daily number of cases. If vaccination rates were maintained at baseline (5,000 people / day) in Model 1, multiple COVID-19 waves would occur, with the next wave peaking by mid-November 2022. In that case, the baseline peak case is reduced by 14%, model 1 is reduced by 21%, and model 2 is reduced by 21%.

In particular, increasing vaccination rates for young adults significantly reduced peak size, but the higher the vaccination rates for both age groups, the more important it is to control the spread of SARS-CoV-2. Researchers have observed that while strengthening transmission control strategies can prevent future COVID-19 waves, mitigating existing control measures will result in new infectious waves.

Conclusion

In this study, researchers developed, parameterized, and analyzed a compartmental mathematical framework for assessing COVID-19 infectious dynamics in a variety of vaccine strategies. The findings show that people under the age of 65 were the main drivers of COVID-19 in Washington.

Importantly, the authors pointed out that vaccines are a high priority. Effectiveness It will increase your chances of reducing illness. In addition, the emergence of new SARS-CoV-2 variants, or mitigation of existing control measures in WA, will cause a more devastating wave of SARS-CoV-2 infection. Overall, advances in current management measures are essential to improving the COVID-19 pandemic.

*Important Notices

medRxiv publishes unpeer-reviewed preliminary scientific reports and should not be considered definitive, guide clinical / health-related behaviors, or be treated as established information.