Epidemiology of Respiratory Syncytial Virus and Potential Public Health Impact of Vaccination

Dear Colleagues,

The global burden of human respiratory syncytial virus (hRSV) lower respiratory tract infection (LRTI) in young children is high. Annually, 33 million episodes of hRSV-LRTI are reported among children younger than 5 years, resulting in 3.6 million hospitalizations and nearly 120,000 deaths.

Although it is estimated that hRSV affects almost all children worldwide at least once within the two years of life, the global burden of hRSV infections extends beyond very young children, remaining frequent also at later ages, including subjects with underlying medical conditions, the elderly, and immunocompromised individuals, which are increasingly being recognized as vulnerable populations at greater risk of adverse outcomes and death.

In infants, hRSV is the second leading cause of bronchiolitis and pneumonia, particularly during the winter months in temperate countries and during the rainy season in tropical countries.

In addition, reinfections may occur throughout life because of the lack of complete or long-lasting immunity, usually associated with milder outcomes in older children and healthy adults. Subsequent infections are commonly less severe than the initial episode as a result of the immune response that is established after exposure to the virus. Nevertheless, the immune response is not able to prevent clinical re-infection even in the absence of hRSV strain variation.

hRSV is an RNA-enveloped virus classified into two highly divergent phylogenetic subgroups A and B, with a genome containing ten genes that encode eleven different proteins; three of those are non-structural proteins and eight structural proteins, either internal or external.

Among these, the two surface glycoproteins, the attachment (G) and the fusion (F), are fundamental to promoting viral infectivity and pathogenesis, being strictly required to mediate virus entry.

In contrast to the G protein, the F protein is known to have a high level of sequence conservation among hRSV subgroups/genotypes, is more immunogenic than glycoprotein G, and also contains six epitopes (Ø-V) capable of inducing a neutralizing antibody response. Therefore, most of the treatments available for the prevention of hRSV disease based on prophylactic monoclonal antibodies (mAbs) or licensed vaccines target the pre-fusion conformation of the F protein.

To date, the use of the long-acting mAb nirsevimab (Beyfortus™) has been approved for passive immunization to prevent hRSV-associated LRTI among all infants and young children, regardless of the presence of pre-existing diseases or predisposing risk conditions. Among adults, a unique vaccine (Abrysvo™) has been approved for use in pregnancy, with the aim to passively protect infants against LRTI within the first semester of life, while two different vaccines (Abrysvo™ and Arexvy™) have been licensed to protect individuals aged ≥60 years of age. In addition, an mRNA-based vaccine will be introduced shortly for use in adults 60 years of age and older.

In this exciting context, Pathogens will launch a Special Issue entitled “Epidemiology of Respiratory Syncytial Virus and Potential Public Health Impact of Vaccination” with the aim of contributing to the current knowledge regarding the epidemiology of hRSV but also the potential underlying effect of immune pressure on genetic diversity and polymorphisms in circulating viruses, which may be able to progressively interfere with the efficacy of vaccines and immunoprophylactic measures in the next future.

I would like to invite colleagues to submit their manuscripts in this field, in the form of original research, review articles, as well as short communications. Potential topics include, but are not limited to:

• Epidemiology;
• Molecular surveillance;
• Public Health;
• Vaccination and immunoprophylaxis;
• Evolution and phylogenetics;
• Genomics and genetics.

Dr. Fabio Tramuto
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Pathogens is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• respiratory syncytial virus
• epidemiology
• public health
• co-infections
• re-infection
• vaccines
• monoclonal antibodies
• molecular surveillance
• genomics