Vaccine Adjuvants and Immunological Considerations in the Pre- and Post-COVID Era

Dear Colleagues,

While highly infectious diseases such as pertussis (whooping cough), rubella and polio are an illustrious part of history for many, only a century ago, infant mortality rate in the US was over 20 percent. Another 20 percent died before the age of five. In general, before the introduction of preventive therapeutics and sanitation, life expectancy was estimated to be <50 years, with bacterial infections taking the majority of lives. Since the discovery, development and widespread use of vaccines, arguably the single most important achievement in immunology, these diseases have been contained or even eradicated. Understanding the crucial factors underlying protective immunity by the currently wide variety of vaccines came later, in tandem with far-reaching discoveries including (but clearly not limited to) dendritic cells by Ralph Steinman, toll-like receptors by Bruce Beutler and Jules Hoffmann and cell-mediated immunity by Peter Doherty and Rolf Zinkernagel.

Now, after a hundred years of vaccine research and empirical application, the societal urgency of the COVID-19 pandemic has impacted vaccine research in unprecedented ways. The popular “bed-to-benchside” trope has demonstrated its plausibility in a single year with the widespread implementation of mRNA-based or lipid nanoparticle (LNP)-derived vaccines. However, fundamental research on its immunological mode of action must catch up and requires careful study when considering its use beyond SARS-CoV-2. Indeed, adjuvant research has for decades shown its capacity to boost and maintain the immunological efficacy of the newest vaccine modalities. As new modalities are now being explored, understanding the adjuvanticity of vaccines and the combination with known and novel adjuvants is crucial to fight the diseases of tomorrow, while limiting side effects.

Hence, this issue of Vaccines will focus on new adjuvants in combination with novel vaccine modalities.

Dr. Sjoerd T. Schetters
Guest Editor

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• adjuvants
• lipid nanoparticle
• mRNA vaccine
• vaccine
• synthetic TLR stimulus
• adaptive immune response
• trained immunity