In December 2019, a new and highly pathogenic coronavirus emerged—coronavirus disease 2019 (COVID-19), a disease caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), quickly spread throughout the world. In response to this global pandemic, a few vaccines were allowed for emergency use, beginning in November 2020, of which the mRNA-based vaccines by Moderna (Moderna, Cambridge, MA, USA) and BioNTech (BioTech, Mainz, Germany)/Pfizer (Pfizer, New York, NY, USA) have been identified as the most effective ones. The mRNA platform allowed rapid development of vaccines, but their global use is limited by ultracold storage requirements. Most resource-poor countries do not have cold chain storage to execute mass vaccination. Therefore, determining strategies to increase stability of mRNA-based vaccines in relatively higher temperatures can be a game changer to address the current global pandemic and upcoming new waves. In this review, we summarized the current research strategies to enhance stability of the RNA vaccine delivery system.

Lignin nanoparticles (LNPs) were prepared with the objective of evaluating their application as a novel oral drug delivery system.

Vaccination is considered one of the most successful public health interventions of the modern era. Vaccines are categorized based on the antigen used, delivery system and the route of administration. Traditional vaccines are produced from the dead, attenuated or inactivated pathogens that cause disease. However, newly developed vaccines are DNA based, liposome based, and virus like particle (VLP) based which are more effective and specific to some malignant diseases. The delivery system of vaccines has been advanced along with time as well. New delivery systems such as nanoparticles, liposomes, or cells (for DNA) has been proven to develop a more efficient vaccine. Most vaccines are administered via intramuscular (IM), subcutaneous (SQ) or oral (PO) route. However, these routes of administration have limitations and side effects. An alternative route could be oral cavity administration such as buccal or sublingual administration using film dosage form as delivery vehicle. In this article, we thoroughly reviewed the possibility of developing a quickly soluble film-based delivery system for vaccine administration. We reviewed the different types of new vaccines and vaccine formulations such as VLP based, liposome, bilosome, particulate, and summarized their suitability for use in a film dosage form. Quickly soluble film dosage form is the most optimized form of buccal administration. A film dosage form applied in the buccal cavity has several advantages: they can avoid first pass effect, they are easy to administer and prepare, and they are more cost effective. Since there is no first pass effect, only a small quantity of the vaccine is needed. Vaccines in their original form or in a nano or microparticulate form can be used in a film. The film can also be developed in multilayers to protect the vaccine from degradation by saliva or swallowing. Films are easy to prepare, administer, and can be used for systemic and local action. In addition, most of the current vaccines use mostly the parenteral route of administration, which has some major drawbacks such as poor induction of mucosal immunity, less patient compliant, less potent, high cost and cumbersome production process. Sublingual and buccal vaccine delivery can be good alternatives as they are easier to prepare and safer than parenteral administration routes. The buccal and sublingual administration have the advantage to produce both systemic and mucosal immunity.