The very young and very elderly are particularly susceptible to many infections and for many infections, age will predict how likely someone is to die once infected. The immediate and long-term effects of an infection changes throughout our life course. Some infections which if caught as a child are usually relatively trivial are likely to be much more severe in young adults including mumps and chickenpox.
Other infections present in very different ways depending on the age of the sufferer; for example, severe malaria in young children is a completely different disease from severe malaria in adults although the parasite is the same. Otherwise trivial infections can have major effects in pregnant women or particularly on their unborn babies; examples include rubella and Zika. Several vaccines work differently in different age groups. This changing pattern of what makes disease severe as we progress from the first trimester of pregnancy by stages through to becoming very elderly has implications for treatment and prevention of disease.

Christopher Whitty CB FRCP FMedSci is Gresham Professor of Physic (the term for medicine when the post was created in 1597) at Gresham College. He is also Chief Medical Officer (CMO) for England, the UK Government's Chief Medical Adviser, Chief Scientific Adviser at the Department of Health and Social Care and head of the National Institute for Health Research (NIHR).
He still practices as an NHS Consultant Physician at University College London Hospitals (UCLH) and the Hospital for Tropical Diseases. He is involved in many day-to-day public health decisions for the UK.
He is a Fellow of the Academy of Medical Sciences. He was interim Government Chief Scientific Adviser and Head of the Science and Engineering Profession and was previously Chief Scientific Adviser at the UK Department for International Development (DFID). Before becoming CMO he was Professor of Public and International Health at the London School of Hygiene & Tropical Medicine, and was previously Visiting Gresham Professor of Public Health.
Professor Whitty has worked as a clinician and in public health and clinical research in the UK, Africa and Asia. He undertook his postgraduate training in epidemiology, economics and medical law.
The major cancers and their prevention and treatment are the theme for his second series of lectures as Gresham Professor of Physic.
Professor Whitty's lectures series are as follows:
2020/21 Major Debates in Public Health
2019/20 Cancer: A Fight we are Steadily Winning (series continued into 2020/21)
2018/19 Infections Diseases: The Oldest Enemy
2017/18 Chronic Diseases (as Visiting Gresham Professor of Public Health)
2016/17 Bold Ideas in Medicine (as Visiting Gresham Professor of Public Health)
2014/15, 2015/16 Medicine at the Extremes of Life (as Visiting Gresham Professor of Public Health)
2013, 2014 and 2016 Imported Infections and Epidemics (as Visiting Gresham Professor of Public Health)
All lectures by the Gresham Professors of Physic can be accessed here.