Picture a crowd of scientists waving placards plastered with photographs of stroke victims and sufferers of Parkinson's disease. They are demonstrating outside the corporate headquarters of British Airways, Lufthansa and Delta, demanding that the airlines stop impeding the biomedical research that could deliver big advances against these and other diseases.

Seem far-fetched? Maybe. But if scientists want continued access to animals as research models, they will have to appear on the front line with every bit as much visibility, determination, organization and persistence as animal-rights activists now muster.

In a renewed campaign targeting transportation companies, protestors have found a public pressure point so effective that only a few major airlines still agree to transport non-human primates bound for research labs (see page 381). Nor is the focus confined to primate transportation: earlier this year, the last ferry company that was willing to carry research rodents into the United Kingdom stopped doing so. Such blocks, scientists warn, could shift much animal work to countries where regulations are more lax.

But there is a silent majority for whom the activists do not speak. This includes most scientists, many ordinary citizens and millions of patients and their families touched by disease and injury. This constituency must mobilize in the defence of human health if the gains enabled by future primate research — and, ultimately, all animal research — are not to be thrown away.

Silence from the research community will mean lost access to research animals.

Scientists and their allies must, of course, continue to be open about the price animals pay in research. They must openly acknowledge, immediately correct and do everything they can to prevent lapses in the care of the animals in their charge. At the same time, scientists must make every effort to use lower animal, and non-animal, models where possible, as regulations already require. And alongside all of that, they must emphasize the tangible and compelling improvements to human life that animal research has made possible.

Consider stroke, which affects some 795,000 people in the United States alone each year — 1 person every 40 seconds — at a cost in excess of US$40 billion. More than 1,000 experimental treatments aimed at protecting brains cells in acute stroke have been developed in cells and rodents; none has been effective in humans. So a possible advance in a paper published last month is significant (D. J. Cook et al. Nature 483, 213–217; 2012). Using macaques — animals whose neuroanatomy, genetics and behaviour are far closer to humans than are those of rodents — the study showed that a drug called a PSD-95 inhibitor reduced the volume of brain tissue killed by the stroke and significantly preserved neurological function. It has now moved into human trials, where early results are promising.

Many other advances have been made possible by primate research. Trials of brain–machine interfaces that allow quadriplegics to control robotic limbs with their minds, for example, and of gene therapy for haemophilia B. And deep-brain stimulation to alleviate the symptoms of advanced Parkinson's disease. Primates have also helped the development of antiviral therapies to prevent mother-to-child transmission of HIV; of Rituxan (rituximab), a key drug against non-Hodgkin's lymphoma; and of Benlysta (belimumab), the first new lupus treatment in 50 years. Primates are making possible strides towards a vaccine against Ebola, and they have affirmed that the diabetes drug pioglitazone can slow early Parkinson's disease — a therapy now being taken into human trials.

Future advances of this kind cannot be allowed to stall. The scientific community and its allies in patient and research advocacy groups should mount a vigorous, coordinated campaign to lobby major airlines. They should vocally support companies such as Air France that continue to fly research primates. They should confront others with the human cost of their alignment with animal activists. And to those airlines that are wavering, they should make a pointed, persuasive case.

An apt target in the last category is United Airlines, which merged with Continental in 2010. Continental was the last major US airline carrying non-human primates for research. The now-merged airline, still under the name of United, says it is “in the process of integrating” the former United and Continental policies on transporting research primates, for publication this autumn. Only a powerful and visible public campaign urging United to transport research primates will give the firm the political cover it needs to take such a position.

Urgent and dramatic action is necessary. It is increasingly clear that silence and passivity from the research community will lead to only one result: lost access to research animals in the countries best equipped for their responsible, humane and justified use.