The importance of social networks in the spread of ideas: what Edmund Halley and Isaac Newton can tell us about key opinion leader engagement

What do we mean when we say that someone is a key opinion leader (KOL)? That they are an expert in their field? That they are a frequent publisher or speaker? That they influence clinical practice through positions with international or national organisations? Is an opinion leader someone who has extensive social connections with their peers through which they exert influence? Or someone held in high esteem by their peers? I’d argue that all of the above are important when identifying and engaging with KOLs. In this blog, however, I want to look at one particular dimension of opinion leadership; social connectivity and network analysis, and how these relate to KOL identification and engagement.

Newton & Halley

Information and influence in social networks

The social relationships between people are important in the development and spread of new ideas because of two principles:

  • Rather than make up their own minds when presented with information, individuals look to their social network to decide whether to adopt a new idea or not.
  • Information and ideas flow through a population of people through social interactions.

Key opinion leaders are those who are connected, either directly or through intermediaries, to many others in a network. Their social connectedness means they receive new and diverse information and ideas and are therefore more knowledgeable than others. Their own thinking and ideas also have greater reach within a social network.

Social network analysis – the study of the relationships between individuals – is therefore a brilliant tool for identifying, understanding, and engaging with, KOLs. Social networks are not just some dry theoretical construct but a vital force in the development and acceptance of new ideas and thinking. To demonstrate the importance of social relationships in the development and spread of ideas, we’re going to look at how the most important scientific theory ever came to be developed.

Edmund Halley, Isaac Newton and Newton’s three laws of motion

In 1684, 28 year old Edmund Halley was the astronomy community’s brightest young star (the comet is named after him). He knew or corresponded with nearly all the great minds in European science; he had worked with the great Belgium astronomer Johannes Hevelius; he was assistant to the Astronomer Royal John Flamsteed, and, when he wasn’t working on his lunar observations, spent his time discussing the latest ideas and theories with fellow members of the Royal Society. It was in one of these London coffee house discussions in January 1684 that he posed the question which led to the publication of the most important book in history of science. While discussing the dynamics of planetary motion, Halley asked two friends, Christopher Wren and Robert Hooke, if the force that kept the planets moving around the sun could decrease as an inverse square of the distance? Wren and Hooke laughed. The ‘inverse square law’ was not a new concept: it was the principle upon which all the laws of celestial motion were established. The problem was that nobody had found the mathematical means to prove it. Wren confessed that he had been working on the proof for some time himself but without success and, eager for a solution, he offered a cash prize to whoever could provide the proof. Hooke said that he had already proved it and that he would provide the calculations in two months’ time.

Seven months later, however, when neither Hooke nor anyone else had produced the proof, Halley decided to look elsewhere for the answer. There was an academic in Cambridge who had a reputation for scientific and mathematical genius, and Halley thought it worth discussing the problem with him. He knew the man was a recluse who rarely communicated with the rest of the scientific community, so rather than write to him and receive no reply, Halley decided to meet him in person.

Which is how, in August 1684, Halley ended up sitting in a study at Trinity College, discssing planetary motion with Isaac Newton. Halley asked Newton what curve would be made by the planets around the Sun ‘supposing the force of attraction towards the Sun to be reciprocal to the square of their distance from it’. Newton immediately replied that it would be an ellipse. Halley, ‘struck with joy and amazement’, asked him how he knew this. ‘Why’, said Newton, ‘I have calculated it’. But Newton had carried out these calculations almost 20 years previously, when he was a student, and now couldn’t find them. So Halley made Newton promise to do the calculations again and send him the proof. Two months later, Newton sent Halley De motu corporum in gyrum, which proved the ‘inverse square law’ and Halley arranged and paid for its publication himself. But Newton didn’t stop there: in 1687, he sent Halley a further work, Philosophiæ Naturalis Principia Mathematica, which extended Newton’s work on the movement of planets around the sun, into a general theory of celestial motion.

Halley, Newton, information and influence

The development and spread of new ideas is not simply great minds experimenting and theorising. The great minds do experiment and theorise but they don’t do it in isolation, there is a social dimension to scientific discovery. Within this social dimension individuals receive information and spread influence.

We can see the importance of social relationships for the flow of information. Halley’s thirst for ideas and knowledge can be seen through the diverse relationships he has within the scientific community – Hevelius, Flamsteed, Wren and Hooke – he likely isn’t influencing these people, but he has learnt from them. Unsatisfied with the knowledge offered by his coffee house clique, Halley went looking for information elsewhere through a different social connection (an example of the concept of weak-ties, that communication between close and similar associates is easy and frequent, but that it is the communication between dissimilar associates, so-called weak-ties, that is often the most crucial in the diffusion of innovation). And the meeting between Newton and Halley in Cambridge is vital because Newton learns that the scientific community wants this proof.

But relationships aren’t just a tool by which information flows, they are also a way that information and ideas are validated by opinion leaders. Halley already has the idea of the ‘inverse square law’, but it is only because Wren and Hooke confirm its importance that he goes on his quest to find the proof. For Newton, his ideas only become known to the scientific community through his relationship with Halley. Halley publishes the two books and through his influence makes sure that Newton’s ideas become known. It is important to recognise though that social influence isn’t the only type of influence. Generally the individuals who are most esteemed for their expertise are also the most socially connected both because their social connectedness fuels their expertise and also because their expertise attracts ever more social connections. However, it is not always the case. If we had conducted a social network analysis of English natural scientists at the beginning of 1684, then the esteem that Newton was held in by his peers wouldn’t be apparent. He would have seemed far less important than countless members of the Royal Society who the world has long forgotten.

What social network analysis can tell us about opinion leaders

By studying social relationships, we can understand the flow of influence and information through a social network. The position of an individual within a network can also tell us a lot about their influence, who influences them, and their attitude to new ideas and information. This is to some extent a matter of interpretation rather than black and white answers, which is why we always recommend to clients that social network analysis is accompanied with a face-to-face consultation and interpretation session. However, there are some common positions that individuals have within networks that can tell us a lot about the type of opinion leader they are, and how to engage with them and the network.

Central Hub

Central Hub

In the network map above, the circles are experts, and the lines between them social relationships. The social-connectedness of each expert, their centrality to the network, is calculated. The larger the circle, the higher their centrality. The red circle above is the most well-connected individual in this network and they are so well-connected that all other individuals seem to fan out from this one central hub, like spokes from a wheel. This particular individual is likely to influence the rest of the network to a huge extent. When engaging with this disease area, the overwhelming influence of this one individual would mean that they would need to be central to any engagement strategy. In particular, the individuals most closely connected to the central hub, the cluster encompassed by the dotted line, are likely to all hold very similar views to the central hub – useful to know when planning advisory boards and other activities seeking feedback.


Boundary Spanners

The two individuals highlighted in red above are the bridges by which information travels between the two most important clusters in this social network. There are several individuals who have more extensive connections than these two within the network (we can tell from the size of their circles) but their position at the cross-roads of the flow of information means they are likely more important than anyone realises. Like Edmund Halley, their diverse relationships mean that they are interested in new and different ways of thinking. When planning how to engage with this network, we would emphasise:

  • Their importance is likely only apparent through social network analysis, they are therefore hidden opinion leaders;
  • They are probably early adopters, who are open to new ideas and thinking;
  • And because they are open to new information, when providing feedback they are likely to supply information about the latest ideas.

Boundary Spanner


In the network above, there is one cluster of individuals, on the right, that appears to dominate the whole disease area. Because the individuals within this cluster are highly interconnected, we can conclude that they are heavily influenced by the thinking of their peers, probably to a far greater extent than the individuals outside the cluster. Often the most well-connected individual within the cluster, the central hub, is the bridge by which new ideas and information flows into the cluster, but that isn’t the case here. In the same way that Halley was on the edge of the clique of London scientists, part of the group are also looking outwards. In the network above the two individuals highlighted in red are on the edge of the cluster, but also the means by which new information is introduced. When seeking to engage with this cluster, it is worth knowing that these two individuals are likely to be the most open to new ways of thinking.

Structural holes in a network


A social network is the means by which the development and diffusion of new ideas takes place. Some networks are more conducive to the diffusion of innovation than others. A few months ago we conducted an opinion leader identification project for a client. One doctor was a clear opinion leader: he had published many influential and well-respected articles, was a member of a national society’s advisory board and, when we interviewed his peers, was always mentioned as someone whose opinion they respected. However, when we conducted social network analysis of the disease area, we could see that this opinion leader (lone red dot on the left of the map) was socially isolated from the rest of the community, in particular from the cluster in red on the right. Like Newton he had authority, but he didn’t exercise that authority through personal interaction, which is why his centrality score is low and his circle small. We therefore recommended to our client that they ‘fix’ the social network by providing a connection between the lone opinion leader and the dominant cluster. This would make the social network more conducive to the development and spread of ideas. This may seem a small thing, but if Halley had not fixed his social network by establishing a relationship with Newton, we may never have heard of Isaac Newton at all.

This is a flavour of how social network analysis can be of benefit when identifying and working with opinion leaders. Far from being some dry scientific theory, social network analysis can bring you closer to the opinion leaders you engage with.

What is a KOL in healthcare?

The concept of key opinion leader (KOLs) was born out of the work of agricultural sociologists in the 1940s. Researchers such as Bryce Ryan and Neal Gross (1943) were interested in understanding why new innovations in corn seed, which were obviously beneficial, were not immediately taken up by farmers in Iowa. They discovered that the decision-making process was less rational and more social than people had supposed; most of the farmers only adopted the new, better, hybrid corn seed once an influential member of their social network did so. These influential people were the keys that led to the changing opinion and behaviour of others.

Studies throughout the latter half of the 20th Century confirmed that this phenomenon was not limited only to farmers in Iowa. As summarised in Everett Rogers’s 2003 book Diffusion of Innovations, from villagers in Peru (Wellin 1955) to the top-brass in the British Navy (Mosteller 1981), the same pattern is seen repeatedly, individuals make irrational decisions about adopting new ideas and products. Time and again, KOLs in networks (sometimes referred to as early adopters) were seen to hold the key to adoption of beneficial innovations. Coleman, Katz and Menzel’s 1955 study on the adoption of tetracycline among medical doctors found the same pattern of behaviour; most doctors only adopted the new drug when a KOL in their network had already done so.

A KOL in healthcare is therefore someone who holds influence over treatment in a particular therapy or disease area. While the Coleman, Katz and Menzel study focused on the physicians in one medium-sized American city, the term KOL is now more commonly taken to mean someone with influence nationally or internationally, someone who is likely to:

  • Publish widely
  • Be highly cited
  • Conduct clinical trials
  • Speak at congresses and educational meetings
  • Sit on the advisory boards for societies
  • Serve on the editorial boards of journals
  • Develop guidelines or other protocols

Such a person will be the KOL in their community, which nowadays is not seen as a geographic community, but a community of specialists in a disease area. These KOLs hold the key for the adoption of new treatments and medications in a disease or therapy area.

How to improve your KOL Engagement #4 How do we communicate internally?

Our fourth tip on better KOL Engagement is to prioritise internal communication about key opinion leaders and the activities you conduct with them. Almost every company we work with admits to having difficulties with this so don’t be despondent if you feel this is an area that needs to improve. It is possible that different silos within your company – whether scientific, marketing, medical affairs, local or global – are unaware who the others are working with. Disjointed KOL interaction leads to a dissatisfied KOL and inefficient KOL activities.

There is no stock solution – what works will be specific to your company’s needs, processes, resources and budget. However, processes do need to be created that ensure that all areas communicate with each other and that you know which KOLS have been engaged with and will be engaged with. The ideal way to create these internal processes is to set up a working group to establish the KOL engagement processes, either brand or therapy area specific or across the whole company. This working group is an opportunity both to diagnose the problems with the current system and to share best practice and hence decide what processes will be needed, however, a starting point for this work would be to consider the following.

Firstly, how is knowledge of KOLs, and information about the activities that teams have conducted with them, shared? This information also compliments any formal KOL identification and mapping process you have or will carry out (as seen in tip 3 article).

Secondly, because effective KOL engagement is built on trust and mutual knowledge, the most effective KOL management programmes are long-term, certainly for the lifecycle of the product and maybe for the whole of the KOL’s career. This means the relationships will need to be passed from medical to marketing or medical affairs and in the case of international KOLs from the global or regional organisation to the countries and sometimes vice versa. How will this be decided and communicated within your company?

Thirdly, there will be limits on how much time any KOL will give to an individual company – determined by regulatory factors; company set limits; budget; or limits decided by the KOL. With international KOLs balance needs to be struck between global and local activities, and you will want to consider when an international KOL is most needed at a local level (normally in the run-up to launch). Again, there will need to be an agreement about how this is managed between different areas.

KOL engagement can be resource heavy and even small improvements in coordination of information and activities can reap enormous benefits.

How to improve your KOL Engagement #2 Think about the KOL’s point of view

The great Enlightenment philosopher Immanual Kant based his systematic moral philosophy on the idea that we should never treat people solely as a means to an end but instead always recognise them as an end in themselves. This is something that we should bear in mind when working with key opinion leaders (KOLs). It is easy when you have your own targets to achieve to see KOLs as means to achieve your own ends – what do I want them to present on, what advice do I want from them, etc. We know this from our own relationships but we often don’t apply it to our jobs. You should look at this relationship as much from the point of view of the key opinion leader (KOL) as from what you want out of it. Why should they want to get involved with your company? What’s in it for them? This will depend on her interests, the nature of your product, especially whether it is a genuine advance, and the stage in its lifecycle. Reasons for getting involved may be the opportunity to get to know your product early, to participate in educational initiatives, or maybe just because it is rewarding to advise on marketing matters through an advisory board.

For most opinion leaders, at least one of the attractions of developing a relationship with a company is the opportunity for research. If opinion leaders have a positive experience with the product and the company, they are likely to become supporters of that product. But, according to CenterWatch, a US-based clinical trials listing service, companies are not making the most of the opportunity to build good relationships with investigators. CenterWatch undertakes surveys in the US and in Europe to find out what investigators think of the pharma companies that sponsor trials. In their latest US survey looking at relationships between companies and trialists, they reveal there is a gap between the companies who are excellent to work with, and those who are less so. Indeed, in the 2021 survey five of the fifty-three individual companies rated improved their performance across all their areas but most of the others fell below their 2019 score indicating that companies are getting worse at KOL relationships, or KOLs are demanding more fulfilling relationships with companies. Certainly, when advising companies on their KOL engagement, we often have to remind our clients that while the reason they want a KOL to work for them is important, they also need to consider why a KOL would want to work with them.

Reading back over this, we realise that this may be read as a calculated way of working with KOLs but actually the relationship works best if we are open, honest and want the best for the KOLs. While we want our KOL engagement strategy to be objective, we want our relationships with KOLs to be authentic, or, as Kant may say, we want to see them as ends in themselves, rather than as means to our ends.

How to improve your KOL Engagement #1 Start early

The relationship with a key opinion leader (KOL) should be a mutually beneficial long-term one. The earlier you can start this the better; firstly it takes a long time for trust to develop. Secondly, the input of KOLs is beneficial at all stages of a product’s lifecycle. Some companies claim to start their opinion leader programmes as early as the pre-clinical phase and most have some sort of opinion leader programme in place by the end of phase II. However, the main role of opinion leaders at this stage is to input clinical advice and their commercial input can be underestimated.

In an analysis in the US almost 90% of pharmacy companies claimed to have started their opinion leader management activities by the end of Phase II. There may be some wishful thinking here, but it shows the increasing importance companies are giving to starting early.

In the early stages the relationship will be mainly facilitated by clinical and the roles of the KOL will also be mostly involved with clinical aspects – advising on medical needs, and on studies as well as taking part in trials. Even at this stage however, the input of KOLs into such things as assessing market needs and competitive analysis is valuable. To get the most out of this early start, it is essential that there is good cooperation and communication between clinical and marketing. In the past, but thankfully less so now, so often there was too little continuity in the relationship with the result that valuable potential advocates developed in the trials process were ignored whilst marketing starts afresh with a new set of opinion leaders. Some of this was down to inadequate process but some was the result of selection of opinion leaders at an early stage with little or no regard to the needs of advocacy support at launch.

However, don’t despair if you’re only a few months away from launch, or even have an in-line product, even at this late stage you can establish strong relationships with opinion leaders; gain valuable advice; and cultivate advocates.

Joe and Neil Kendle