Doubts rise as the risks go down

Between them, mass vaccination and antibiotics were mainstays of a narrative of medical progress that unfolded through much of the 20th century. The sense that life was a lottery, that any one of a raft of diseases could carry off your infant, your spouse or anyone you knew, pretty much any time, gradually waned. Death rates fell spectacularly, and the earlier options of rage or resignation in the face of epidemics were superseded by an intoxicating, sweeping optimism. The Nobel laureate Macfarlane Burnet surveyed the middle of the century and saw "the virtual elimination of infectious disease as a significant factor in social life".

These two books offer more sober reflections, in keeping with less optimistic times. US journalist Arthur Allen chronicles the hard-won successes, and occasional failures, of scientists and public health workers delivering vaccines. British historian Robert Bud examines the later introduction of antibiotics, epitomised by the first "wonder drug" - penicillin. Both eschew simple tales of hubris but show how the complexities of biological and social systems mean that vast success is never without its flaws. Their stories are often intertwined, though not as much as Oxford University Press's press release for Bud's book, mysteriously headed "Do flu vaccines really work?", seems to imply.

Vaccines and antibiotics are similar, but different. Both require insertion of more or less scientifically prepared material into the body. But vaccines have to be administered in advance of illness, ideally to the entire population at risk. Antibiotics usually come into play when someone is already sick, and if they work to show immediate benefit to the individual. This is one key to the differences in perception of the two medical miracles, and to the changing risk calculus that has affected both.

It is a calculus that Allen, who writes the "risk" column for the online magazine Slate, is particularly sensitive to. When everyone knew at first hand what the most feared infectious diseases could do, the majority embraced vaccination wholeheartedly. Allen suggests the peak of trust in vaccines was epitomised by the smallpox inoculation instituted after a brief outbreak of the disease in New York in 1947. Officials decided to recommend vaccinating the entire population, and people willingly queued for their shots - more than 6 million in three weeks.

Allen ascribes this to a combination of the moral and organisational effect of the war. Uniting against a common enemy was the thing to do, and the authorities had unchallenged rights to prescribe how to go about it. No one pointed out that other countries - Britain, for example - dealt with smallpox outbreaks by isolation and vaccination of a few hundred contacts.

Nor, Allen notes, were they much fussed by the six deaths and 100-odd serious injuries caused by the vaccine. The fact that, as in this case, vaccines have always produced untoward effects is why they have so often been the focus for the tensions in public health policies that require people to do something of collective benefit. Some oppose vaccines in principle, as unnatural, ungodly, unkind to the immune system, or just plain objectionable on account of being recommended by the state. More recently, a few are unabashed free-riders, happy to benefit from herd immunity without taking the jabs. But there are many more who are just uneasy about the balance of risk and benefit. They believe, with some justice, that health officials downplay the risks. And they worry about sins of omission rather than commission, especially in care of their children. Allen sympathises, up to a point. He goes deeply into recent controversies - about whooping cough vaccine and brain damage and infant immunisations and autism, for instance - and makes it clear how appalling it is to live with a damaged child when you believe the damage could have been avoided. He is also clear, though, that the evidence of risk is weak to non-existent, especially in the autism case. Anti-vaccine sentiment, today, much as 100 years ago, is rooted in differences in values and world-view from the advocates of science-based public health. And the success of vaccination, in the end, is to have created conditions in which some in the affluent West can afford to shun immunisations for themselves and their children at little or no risk. It seems as much a lifestyle choice as a life-and-death decision. As such, the convinced anti-vaccinators find it easier to influence the waverers' assessments of cost and benefit. An epidemic or two, though, will reset risk thresholds pretty swiftly. Bird flu, anyone?

The antibiotic story has also had its downside, of course, but it is a more direct result of the drugs' success. Doctors' and patients' unbridled enthusiasm for penicillin, though modulated in fascinating ways by the cultures in which it is used, was pretty much universal. The drug, which Bud's social and cultural history treats insightfully as a "brand" as well as a scientific and technological development, ended up in animal feed as well as in a billion medicine cabinets. He does not quite offer the kind of analysis found in Bruno Latour's account of The Pasteurisation of France , with its emphasis on innovation as an unfolding series of social alliances and enrolments, but you might call Bud's exposition an account of the penicillinisation of the world. Yet the vast use of this and other antibiotics put bacteria under powerful selection pressure. "The world is a dilute solution of tetracycline," I was taught in undergraduate microbial genetics in the 1970s. And, as well-informed Darwinians had always predicted, the microbes responded by developing resistance. The so-called "superbugs" that haunt our hospital wards are a natural consequence of exposing every corner of the planet to antimicrobial chemicals.

There is much more to both these excellent volumes. Both recount the role of industry in delivering the vital goods. Allen argues convincingly that blanket provision of vaccines cannot be left to the market, and that this conclusion has been unpalatable to generations of US politicians opposed to government intervention in anything. Along the way, he provides vivid accounts of the development of polio vaccine, and of the growth of universal provision of childhood vaccination. Half a century ago, American children in poor families were lucky to get a single shot for smallpox. By the end of the 1960s they were all supposed to be vaccinated against eight different diseases, most now rarely seen.

Bud complements this by showing how mass production of antibiotics, boosted by wartime needs, fostered the enormous growth of the post-Second World War pharmaceutical industry. He also sketches a historical sociology of doctor-patient relations as a backdrop to the use and abuse of antibiotics.

And he shows how easy access to effective medicine tended to dispel guilt about contracting infection, attenuating the notion that hygiene was a moral imperative. Cleanliness was no longer next to godliness. His book, shorter than Allen's, offers a wider view, though not so broad as to lose its focus on the importance of antibiotics in shaping attitudes to medicine and medical practice. Together, these volumes offer a compelling perspective on the achievements of 20th-century medicine, and how they have given rise to new challenges for the 21st.

Jon Turney is course leader for the MSc in creative non-fiction writing at Imperial College London and author, with Jess Buxton, of The Rough Guide to Genes and Cloning .