Multiple Sclerosis, COVID-19 and Vaccines: Making the Point

Abstract

On 11 March 2020, the World Health Organization declared the coronavirus disease 19 (COVID-19) outbreak a pandemic. In this context, several studies and clinical trials have been conducted since then, and many are currently ongoing, leading to the development of several COVID-19 vaccines with different mechanisms of action. People affected by multiple sclerosis (MS) have been considered high-risk subjects in most countries and prioritized for COVID-19 vaccination. However, the management of MS during the COVID-19 pandemic has represented a new challenge for MS specialists, particularly because of the initial lack of guidelines and differing recommendations. Despite an initial hesitation in prescribing disease-modifying drugs (DMDs) in naïve and already treated patients with MS, most national neurology associations and organizations agree on not stopping treatment. However, care is needed especially for patients treated with immune-depleting drugs, which also require some attentions in programming vaccine administration. Many discoveries and new research results have accumulated in a short time on COVID-19, resulting in a need for summarizing the existing evidence on this topic. In this review, we describe the latest research results on the immunological aspects of SARS-CoV-2 infection speculating about their impact on COVID-19 vaccines' mechanisms of action and focused on the management of MS during the COVID pandemic according to the most recent guidelines and recommendations. Finally, the efficacy of COVID-19 and other well-known vaccines against infectious disease in patients with MS on DMDs is discussed.

Keywords: COVID-19; Disease-modifying treatment; Multiple sclerosis; Recommendations; Vaccines.

Fig. 1

Development of T-cell and B-cell response after vaccination against SARS-CoV-2 and subsequent activation of the immune system in case of infection. The administration of vaccines against SARS-CoV-2 (V) determines the activation of dendritic cells (DC), with subsequent antigen processing and presentation to naïve B, T CD4+ and T CD8+ lymphocytes (a). Naïve B cells differentiate into plasma cells (P), leading to antibody production, and B memory cells. Naïve T CD8+ cells differentiate into memory and cytotoxic cells. Naïve T CD4+ cells, including a subset of Tregs, differentiate into memory and effector T cells (T CD4+ helper and Tregs). T CD4+ helpers support the differentiation of B cells into plasma cells, favoring the humoral immune response. When SARS-CoV-2 infection occurs in a vaccinated subject, the virus initially enters the upper airway epithelial cells (ECs) (b). Memory B cells are able to differentiate into plasma cells (P) with the support of T CD4+ helper cells, leading to antibody production and to regeneration of the pool of memory B cells. Memory T CD8+ cells differentiate into T cytotoxic cells, able to destroy infected cells, and regenerate the pool of memory T CD8+ cells. Tregs modulate the immune response by downregulating antiviral T cell responses, preventing the hyperactivation of the immune system and the consequent tissue damage and cytokine storm driven by T cells, leading to severe COVID-19