COVID-19 Vaccination Update: Fall 2023 Analysis

In May 2023, the World Health Organization (WHO) declared that the COVID-19 global health emergency was officially over, marking a significant shift in the fight against the virus. This decision followed a year of declining COVID-19 cases worldwide. The United States also ended its public health emergency on May 11, 2023, reflecting a similar trend in infection rates.

#Vaccination and Immunity

One reason for the decrease in COVID-19 cases is the increase in immunity levels among the population. This immunity comes from two main sources: effective vaccines and past infections. In the U.S., research showed that the percentage of blood donors with antibodies against the virus increased significantly over time. By the second half of 2022, nearly 96.4% of blood donors had developed some level of immunity, whether from vaccination, past infections, or both.

#Vaccine Evolution

As the pandemic progressed, the types of COVID-19 vaccines available to the public evolved. The mRNA vaccines from Moderna and Pfizer-BioNTech became the most popular options in the U.S. A third option, the protein sub-unit vaccine from Novavax, was also available. With the emergence of new variants, like the Omicron strains, updates to the vaccines became necessary to maintain their effectiveness.

In September 2022, health authorities recommended that everyone aged six months and older receive a new bivalent vaccine designed to cover both the original virus and the latest Omicron sub-variants. By early 2023, another variant, called XBB, had taken over, and studies indicated that existing bivalent vaccines were less effective against it. Because of this, health organizations recommended another round of updates to the vaccines to make them more effective against the XBB variants.

#The Need for Cost-Effectiveness Evaluation

The need to assess the clinical and economic impact of these new vaccines is crucial. Even though the incidence of COVID-19 has decreased, the funding model for vaccines is shifting from emergency procurement to regular purchasing processes for routine Vaccinations. Therefore, evaluating whether new COVID-19 vaccinations remain a good investment for society and the healthcare system is essential.

#Objectives of the Analysis

The goal of this analysis is to examine the potential benefits and cost-effectiveness of the updated mRNA COVID-19 vaccines for the fall of 2023 for individuals aged 18 years and older. This will involve comparing the outcomes with and without a new vaccination campaign. Furthermore, the differences between the Moderna and Pfizer-BioNTech vaccines will be analyzed, as they have different formulations that affect their effectiveness.

#Methods of Analysis

To carry out this analysis, a model called the Susceptible-Exposed-Infected-Recovered (SEIR) model was used. This model helps estimate how many people are likely to get infected with COVID-19 over time and the potential health outcomes, such as Hospitalizations, deaths, and the associated costs.

The analysis focused on two scenarios. The first scenario compares the effects of the updated Moderna vaccine against no vaccination at all. The second scenario compares the effects of the updated Moderna vaccine against the updated Pfizer-BioNTech vaccine.

#The SEIR Model Explained

The SEIR model separates the population into different groups based on their infection status. These groups include:

• Susceptible (S): People who can get infected.
• Exposed (E): People who are infected but not yet contagious.
• Infected (I): People who are contagious and may have symptoms.
• Recovered (R): People who have recovered and have some level of immunity.

The model helps track how individuals move through these stages over time and how vaccination impacts these transitions. Vaccination can lower the number of new infections and reduce the severity of cases among those who do get infected.

#Timeline of the Analysis

The analysis will consider data from September 2023 to August 2024. The first part of the model serves to calibrate the vaccination effects and immune protection up until August 2023. This allows for a better understanding of the population's immunity at the start of the analysis period.

During this period, the model takes into account various factors, such as how quickly immunity wanes after vaccination or infection, which will impact the likelihood of new infections.

#Analyzing the Effects of Vaccination

Vaccinating individuals is expected to reduce both the number of infections and the chances of hospitalization. Each day that passes, newly vaccinated individuals have a specific level of effectiveness against the virus. Over time, this effectiveness may decrease, which is factored into the model.

The expected outcome of the research includes:

• The total number of symptomatic infections, hospitalizations, and deaths for each vaccination strategy.
• An analysis of costs related to COVID-19 treatments and the quality of life years saved by preventing these outcomes.

#Results and Impact of Vaccination Campaigns

The model predictions suggest substantial benefits from the vaccination campaigns. If no new vaccines are administered, millions of symptomatic cases, hospitalizations, and deaths are anticipated. However, with the updated Moderna vaccine, those numbers are expected to decrease significantly.

When the analysis focuses on the newer vaccines, a large number of symptomatic infections and hospitalizations can be prevented, resulting in considerable quality-adjusted life years (QALYs) gained for the population. QALYs take into account both the quantity and quality of life gained from avoiding severe health outcomes.

#Understanding Cost-Effectiveness

From a healthcare perspective, the model estimates the costs associated with both vaccination and treatment for COVID-19. The updated Moderna vaccine is anticipated to be not only effective in preventing infections but also cost-effective over the year-long period.

When looking at scenarios involving older adults, the costs per QALY gained become even lower, indicating that targeting this group with vaccination yields significant health benefits for less investment.

#Sensitivity Analyses and Uncertainty

To ensure that results are robust, sensitivity analyses were conducted. This means that the researchers looked at how changing certain input values-like the effectiveness of vaccines, rates of hospitalization, and patterns of infection-affect the overall cost-effectiveness results.

These analyses help highlight the most influential factors that could alter the findings of the study. Overall, the analyses suggest that, even with uncertainties in the effectiveness of vaccines against new variants, the updated vaccines are likely to remain cost-effective.

#Comparing Moderna and Pfizer Vaccines

In the analysis, the updated Moderna vaccine is expected to outperform the Pfizer-BioNTech version when looking at overall effectiveness and costs. The preliminary results show that the Moderna vaccine could prevent more infections, hospitalizations, and deaths compared to the Pfizer vaccine, making it a more appealing option for public health.

#Conclusion: The Need for Continued Vaccination

This analysis suggests that continuing to use updated COVID-19 mRNA vaccines in the fall of 2023 will have significant benefits for public health. Vaccination can prevent a large number of infections and serious health outcomes while also being cost-effective for the healthcare system.

As COVID-19 evolves from a pandemic to an endemic virus, understanding the efficacy and cost of vaccines will remain crucial in ensuring public safety and minimizing health risks associated with COVID-19. Vaccination efforts should continue to focus on both younger populations and more vulnerable groups, such as older adults, to maximize health benefits and minimize healthcare costs as the situation continues to develop.