Maintaining a 'fit' immune system: the role of vaccines.

INTRODUCTION: Conventionally, vaccines are thought to induce a specific immune response directed against a target pathogen. Long recognized but poorly understood nonspecific benefits of vaccination, such as reduced susceptibility to unrelated diseases or cancer, are now being investigated and may be due in part to "trained immunity'. AREAS COVERED: We discuss 'trained immunity' and whether vaccine-induced 'trained immunity' could be leveraged to prevent morbidity due to a broader range of causes. EXPERT OPINION: The prevention of infection i.e. maintaining homeostasis by preventing the primary infection and resulting secondary illnesses, is the pivotal strategy used to direct vaccine design and may have long-term, positive impacts on health at all ages. In the future, we anticipate that vaccine design will change to not only prevent the target infection (or related infections) but to generate positive modifications to the immune response that could prevent a wider range of infections and potentially reduce the impact of immunological changes associated with aging. Despite changing demographics, adult vaccination has not always been prioritized. However, the SARS-CoV-2 pandemic has demonstrated that adult vaccination can flourish given the right circumstances, demonstrating that harnessing the potential benefits of life-course vaccination is achievable for all.

Capturing the value of vaccination within health technology assessment and health economics: Literature review and novel conceptual framework.

BACKGROUND: Vaccination provides significant health gains to individuals and society and can potentially improve health equity, healthcare systems and national economies. Policy decisions, however, are rarely informed by comprehensive economic evaluations (EE) including vaccination's wide-ranging value. The objective of this analysis was to focus on health technology assessment systems to identify relevant value concepts in order to improve current EE of non-pandemic vaccines. METHODS: Following a literature review, a novel Value of Vaccination (VoV) framework was developed with experts in vaccine EE from developed countries with established health technology assessment systems. RESULTS: Forty-four studies presenting value frameworks or concepts applicable to vaccination were included. Eighteen unique value concepts relevant to EE were identified and defined. These were categorised within the VoV framework using three dimensions, moving from a narrow payer perspective to a more expansive and societal perspective. The dimensions were: (I) conventional payer perspective concepts (e.g., health gains in vaccinees, direct medical costs); (II) conventional societal perspective concepts (e.g., indirect health/economic gains to caregivers/households, productivity in vaccinees); and (III) novel societal concepts (e.g., financial risk protection, peace of mind, societal health gains, healthcare systems security, political stability, social equity and macroeconomic gains). While good quality evidence and methods are available to support concepts in Dimensions I and II, further work is needed to generate the required evidence for vaccination impact on Dimension III concepts. CONCLUSIONS: The devastating effect on nations of the COVID-19 pandemic has helped to highlight the potential far-reaching benefits that many vaccination programmes can offer. This VoV framework is particularly relevant to policy decisions considering EE, and the potential future expansion of non-pandemic vaccination value considerations. The framework helps to understand and compare current value considerations across countries and payer versus societal perspectives. It provides decision-makers with a transparent and logical path to broaden consideration of VoV in EE.

Lifting non-pharmaceutical interventions following the COVID-19 pandemic - the quiet before the storm?

INTRODUCTION: In the first months of the novel coronavirus (COVID-19) pandemic that begun in 2020, non-pharmaceutical interventions (NPIs) have been adopted worldwide. However, the effects of NPI implementation go beyond slowing the spread of COVID-19. Here, we review the non-intended effects that may have arisen from prolonged application of NPIs. AREAS COVERED: NPIs also affected the epidemiology of other infectious diseases, with unprecedentedly low circulation of several respiratory and gastrointestinal viruses being observed worldwide in 2020. While this was a welcome effect for already strained health-care systems, prolonged low exposure to pathogens may result in an increased pool of individuals susceptible to certain diseases. Out-of-season or unusually intense outbreaks of non-vaccine preventable diseases have already been documented as NPIs were gradually eased. In the context of widespread and important disruptions in national vaccination programs during the early phase of the pandemic, the risk of vaccine-preventable disease resurgence after NPIs are lifted cannot be excluded either. EXPERT OPINION: Awareness must be raised of the risk of vaccine-preventable disease resurgence, and efforts need to be made to mitigate this risk, where possible, by increasing vaccination coverage. Research and regulatory opportunities brought on by the COVID-19 pandemic should be seized.

In the first months of the COVID-19 pandemic, the only methods available to slow the spread of the disease were non-pharmaceutical interventions, such as lockdowns, mask wearing, social distancing, school closures, and travel bans. Even after vaccines against COVID-19 became available, combinations of non-pharmaceutical interventions continued to be implemented by most countries, to various extents. Although these measures lowered the number of people who got sick before vaccines and therapies against COVID-19 were available, they also had other consequences for public health. The non-pharmaceutical interventions implemented worldwide have slowed or even stopped the spread of several infectious diseases: since 2020, fewer cases of flu, bronchiolitis, gastroenteritis, and other diseases were recorded compared to pre-pandemic times. This relatively long 2-year period during which people, especially children, were exposed to fewer infections might mean that their immune systems are less prepared to fight these diseases. In addition, vaccination against diseases other than COVID-19 dropped in the early months of the pandemic, meaning that the number of children and adults who are not protected against vaccine-preventable disease has potentially increased. Easing of COVID-19 restrictions has caused a comeback of some diseases against which no vaccine is available, sometimes with more cases than during the pre-pandemic years; there is a risk that this might happen with vaccine-preventable diseases as well. To prevent outbreaks, routine and catch-up vaccinations against other diseases besides COVID-19 should be encouraged and promoted.