A Comparative Study on the Effectiveness of mRNA and Adenoviral COVID-19 Vaccines in Immunocompromised Populations

Antonelli Riva^*
*Correspondence: Antonelli Riva, Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy, Email:

Introduction

The COVID-19 pandemic has presented significant challenges to global health, especially for immunocompromised individuals who are more vulnerable to severe outcomes from SARS-CoV-2 infection. With the advent of vaccines, there has been a crucial need to understand their effectiveness in these high-risk groups. Immunocompromised individuals, such as those with autoimmune diseases, undergoing chemotherapy, or taking immunosuppressive drugs post-organ transplant, have a diminished immune response. This altered immunity raises concerns about their ability to respond effectively to COVID-19 vaccines [1]. The two primary vaccine technologies—mRNA vaccines (Pfizer-BioNTech and Moderna) and adenoviral vector vaccines (AstraZeneca and Johnson & Johnson)—offer different mechanisms of action, which might influence their efficacy in these populations.

Description

mRNA vaccines: mRNA vaccines work by introducing a small piece of messenger RNA that encodes for the spike protein of SARS-CoV-2. This prompts the body to produce the spike protein, which in turn stimulates an immune response. The advent of mRNA vaccines represents a revolutionary leap in vaccine technology, particularly demonstrated by the success of the Pfizer-BioNTech and Moderna COVID-19 vaccines. As these vaccines have been deployed globally, understanding their mechanism, efficacy and specific impact on immunocompromised populations has become crucial. mRNA vaccines work by introducing a synthetic messenger RNA (mRNA) sequence into the body. This mRNA sequence encodes the spike protein found on the surface of the SARS-CoV-2 virus. When injected into muscle cells, the mRNA instructs the cells to produce the spike protein, which then triggers the immune system to recognize and attack the virus if the body is exposed to it in the future.

Efficacy in immunocompromised populations: Studies have shown that mRNA vaccines can elicit a robust immune response in immunocompromised individuals, although the response is generally lower than in the general population. For instance, research indicates that a significant proportion of organ transplant recipients developed an antibody response after receiving two doses of an mRNA vaccine, though the response rate was markedly lower compared to immunocompetent individuals. The efficacy of mRNA COVID-19 vaccines, such as those developed by Pfizer-BioNTech and Moderna, is a topic of significant interest, particularly for immunocompromised populations [2,3]. This group includes individuals with conditions or treatments that weaken the immune system, such as organ transplant recipients, cancer patients undergoing chemotherapy, people with autoimmune diseases and those living with HIV/AIDS. Understanding the nuanced response of these populations to mRNA vaccines is crucial for optimizing their protection against COVID-19.

Adenoviral vector vaccines: Adenoviral vector vaccines use a modified virus (not the coronavirus) to deliver the genetic material encoding the spike protein. This method aims to induce an immune response without causing disease. Adenoviral vector vaccines, such as those developed by AstraZeneca (Vaxzevria) and Johnson & Johnson (Janssen), have played a crucial role in the global fight against COVID-19. These vaccines use a different technological approach compared to mRNA vaccines and offer unique advantages and challenges, especially for immunocompromised populations. Adenoviral vector vaccines are a vital component in the global strategy to combat COVID-19, offering effective protection, particularly against severe disease and hospitalization. For immunocompromised populations, while the immune response may be lower compared to the general population, these vaccines still provide critical protection. The administration of booster doses can help enhance immunity in these vulnerable groups.

Efficacy in immunocompromised populations: Adenoviral vector vaccines have also been studied in immunocompromised groups. Data suggests that while these vaccines are effective, their immunogenicity may be less robust compared to mRNA vaccines. For example, a study on patients with hematologic malignancies showed that fewer participants developed a detectable antibody response after adenoviral vector vaccination compared to those who received mRNA vaccines. Direct comparisons between mRNA and adenoviral vaccines in immunocompromised populations reveal some key differences like mRNA vaccines generally elicit higher antibody titers in immunocompromised individuals compared to adenoviral vector vaccines [4,5]. This is particularly notable in organ transplant recipients and patients on immunosuppressive therapies. The role of T-cell mediated immunity, which is crucial for long-term protection, appears to be better stimulated by mRNA vaccines.

Studies suggest that mRNA vaccines may induce a more robust T-cell response, which is essential for combating the virus, especially in immunocompromised individuals. Immunocompromised patients often benefit from additional booster doses. Evidence shows that a third dose of mRNA vaccines significantly enhances the immune response in these individuals, suggesting a strategy to improve protection. Immunocompromised patients often benefit from additional booster doses. Evidence shows that a third dose of mRNA vaccines significantly enhances the immune response in these individuals, suggesting a strategy to improve protection.

Conclusion

While both mRNA and adenoviral vector COVID-19 vaccines offer valuable protection to immunocompromised individuals, mRNA vaccines tend to provide a stronger and more consistent immune response. Given the higher antibody titers and robust T-cell responses elicited by mRNA vaccines, they may be preferred for initial and booster vaccinations in these high-risk groups. However, the choice of vaccine should be personalized based on individual health profiles, availability and potential contraindications. Continued research and surveillance are essential to optimize vaccination strategies for immunocompromised populations, ensuring they receive the most effective and safe protection against COVID-19. As the pandemic evolves, so too must our approaches to safeguarding the most vulnerable among us.

Acknowledgement

None.

Conflict of Interest

None.

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