COVID-19 vaccines and vaccine hesitancy: Role of the allergist/immunologist in promotion of vaccine acceptance

Abstract

Background: Vaccine hesitancy has been defined as a delay in acceptance or refusal of vaccines, despite the availability of vaccine services. In the past, despite an impressive record of vaccine effectiveness in the United States, several factors have contributed to a decreased acceptance of vaccines that has resulted in outbreaks of infectious diseases, e.g., measles. More recently, vaccine hesitancy has spread to coronavirus disease 2019 (COVID-19) vaccines. There are many causes of vaccine hesitancy, such as misinformation, fallacies, and myths, that have contributed to vaccine hesitancy. Objective: The purpose of the present report is to address the many causes of vaccine hesitancy and to suggest ways that the allergist/immunologist can be involved in the promotion of vaccine acceptance. Methods: The current COVID-19 vaccines were reviewed, together with their mechanisms(s) of action and adverse reactions to them. Results: The many causes of vaccine hesitancy include many doubts and concerns related to COVID-19 vaccines as well as a diminished level of confidence and trust by segments of the public in the nation's leaders in government, medical, and business communities, that those groups once enjoyed. Conclusion: Vaccination with COVID-19 vaccines is the only way that COVID-19 will be eliminated or at least controlled today, and vaccine hesitancy is the potential nemesis. The present report describes how the allergist/immunologist not only plays a major role in the delivery of specialized therapy of COVID-19 but also in educating the public with regard to the importance of COVID-19 vaccines, in dispelling misinformation, and in promoting trust for vaccine acceptance but must be informed with the most accurate and current information to do so.

Figure 1.

Schematic representation of some of the timeline landmarks of Emergency Use Authorization (EUA) for current and future coronavirus disease 2019 (COVID-19) vaccines.

Figure 2.

How mRNA and AdV vector vaccines elicit immunity to SARS-CoV-2. The two vaccine formulations, i.e., mRNA vaccine(s) and the AdV vectorized vaccine gain entry into DCs, which results in the production of high levels of S protein. In addition, innate sensors are triggered by the intrinsic adjuvant activity of the vaccines, which results in production of type I interferon and multiple pro-inflammatory cytokines and chemokines. RNA sensors, such as TLR7 and MDAS are triggered by the mRNA vaccines, and TLR9 is the major double-stranded DNA sensor for the AdV vaccine. The resultant activated DCs present antigen and costimulatory molecules to S protein–specific naive T cells, which become activated and differentiated into T cytotoxic effector cells or T-helper lymphocytes. TFH cells help S protein–specific B cells to differentiate into antibody-secreting plasma cells and promote the production of high-affinity anti–S protein antibodies. Reproduced with permission from Ref. . mRNA = Messenger RNA; AdV = adenovirus; SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2; DC = dendritic cell; S = spike; TLR = Toll-like receptor; MDAS = melanoma differentiation-associated protein 5; TFH = T follicular helper.

Figure 3.

Conceptual model of vaccine hesitancy that shows the many historic, political, and sociocultural contributing factors. Reproduced with permission from Ref. .

Figure 4.

A 51-year-old woman who experienced a delayed reaction at her arm at the immunization site 8–9 days after receiving the first dose of the Moderna coronavirus disease 2019 (COVID-19) vaccine.

Figure 5.

(A) Mechanisms of hypersensitivity reactions to radiocontrast media (RCM). (B) Postulated mechanisms of hypersensitivity reactions to COVID-19 mRNA vaccines. Modified with permission from Ref. .