Vaccination against diseases such as influenza is obviously important at all ages, and catch-up vaccination of adults who have missed vaccines as children is sometimes necessary, but certain vaccines are aimed specifically at the adult age group, including those against human papillomaviruses, meningococcal, group B pneumococci, and zoster.

It must be borne in mind that vaccination is particularly important in older adults, in whom senescence of the immune system is an important phenomenon that increases the danger of infection. That phenomenon has been quite important during the COVID-19 outbreak, but it plays a role with all infectious diseases of the elderly. Moreover, vaccination of children has allowed more of them to survive into adulthood, and so they also need protection from adult diseases.

As one who first visited India in the 1960s, I have witnessed there, the growth of the vaccine industry and an increase in vaccine experts and vaccine expertise. This book will serve to augment vaccination of adults not only in India but also in neighboring countries in which vaccine-preventable diseases continue to occur, and in which increased knowledge of vaccines will help to decrease mortality and disease.

In spite of scientific advances and improved coverage in children, the knowledge, information, and practices on vaccines and immunization have largely focused on children without any significant and systematic approach to address the needs of vaccines beyond this age group. Even in the many affluent and developed nations with successful and coordinated childhood immunization programs, the vaccine coverage beyond the pediatric age group has remained suboptimal leaving a significant gap in the protection provided by the vaccines to the community at large. Available information has shown that a doctor's recommendation is the single most important factor in improving vaccination rates.

With the COVID-19 pandemic and development of vaccines against it, the concept of prevention got a shot in the arm and a paradigm shift to increase a general awareness and relevance about the role of vaccines in the prevention of morbidity and mortality in adult populations too. At the same time, the changing demography, prevalence of lifestyle diseases, epidemiological shift of vaccine-preventable diseases (VPDs), increasing life expectancy of the people and national health economics are the potential driving forces to reap the immense and expandable but unfulfilled benefits which the science and technology of vaccines has to offer to all those eligible adults. Unlike routine childhood immunizations, the needs and recommendations for adults would vary and be based upon on the age, prior vaccinations, existing health conditions, medication history, lifestyle, occupation, travel, and exposure. It is time now that adult vaccinations and their practice need to be planned and implemented to become an inclusive national health priority.

Healthcare professionals belonging to wide spectra of clinical medicine and its different specialties can be effective partners in generating awareness to the public at large beyond the traditionally targeted age groups to maximize the full benefits of life-saving interventions that vaccines offer. With the ease of availability of online information to lay public, its acceptance or otherwise would need to be scrutinized for practical implications. Beyond the childhood, vaccinations need to become a tool for healthy aging.

The book has been purposefully written in a Question–Answer format and as a ready-reckoner to simplify the available literature, to be easy to read and practice and to include the essential and practical aspects of vaccines and immunization from an adult perspective. This should hopefully be a helpful and an updated guide to further an awareness and skills in the use of vaccines for the adults. Eminent contributors from different medical specialties have come together in this book to collate available evidence and guidelines in the present context as a practice tool for adult vaccinology. The basics of immunization, individual vaccines, the use of vaccines in special situations, and COVID-19 vaccine and its evolving recommendations thus form an integral part of the book. The book should be practically useful to different medical doctors from general practitioners including family physicians, consultants, and super-specialists.

We earnestly anticipate and hope that the book serves its purpose to spread the awareness about vaccines to be a routine component part of health care in adults and elderly, and decrease the burden of infectious diseases in the people. The provider and the patient education along with public health policies can become a promising endeavor and a future road map of healthy life of adulthood. The challenges are ubiquitous, but an active collaboration between government/private sector, different stakeholders and policy makers can facilitate the vaccine access to eligible adults contributing to strengthening adult immunization practices in the years ahead.

As such, the idea of a book dealing with a relatively dormant topic on adult immunization could have not been conceived and delivered, unless there were committed contributors who were from different specialties to deal with the subject within the given time frame.

When Dr Stanley A Plotkin, the Father of Modern Vaccinology and Professor Emeritus of Virology, University of Pennsylvania, USA, readily agreed to pen a foreword for the book, we felt truly honored and blessed and felt a push within ourselves to make our efforts as perfect and as flawless as possible. For a tireless advocate, researcher and a crusader that Dr Plotkin is, since 1957 for the protection of human beings against infectious diseases, the words can never be enough to express our honest gratitude to him.

We have been extremely fortunate to have contributions from a wide range of eminent researchers, public health experts, medical specialists, young budding consultants, and other faculties to spare their valuable time and give us an updated and value-based additions to the contents of the book. Even within a shortened time-frame, they have always responded quickly and helped us in a positive manner. Their contributions reflect dedication, commitment, and expertise in vaccines and immunization. We owe them our gratitude.

We sincerely appreciate and acknowledge continued assistance and encouragement from Shri Jitendar P Vij (Group Chairman), Mr Ankit Vij (Managing Director), Ms Chetna Malhotra (Senior Director—Professional Publishing, Marketing and Business Development), Ms Pooja Bhandari (Production Head), and Dr Rajul Jain (Development Editor) of M/s Jaypee Brothers Medical Publishers (P) Ltd, New Delhi, India, throughout for efforts in ensuring the quality and the publication of this book in a timely manner.

The selfless support from our family members for bearing with us and busy schedules is also sincerely acknowledged and that has acted like a “booster shot” to keep us energized, motivated and on the go!