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Rob Wiblin

Giving What We Can's charity recommendations - currently 

 - are generally regarded as the most reliable in their field. I imagine many readers here donate to these charities. However, it is surprising that it is potentially pretty easy to start a charity more effective than any of them.

All you would need to do is found an organisation that fundraises for whoever Giving What We Can recommends, and raises more than a dollar with each dollar it receives. Is this hard? Probably not. As a general rule, a dollar spent on fundraising seems to raise at least several dollars. It's a pretty simple and fast multiplier that obviously beats putting your money in the stock market. An independent organisation raising money for Giving What We Can's top charities should do even better than a typical fundraiser, thanks to:

the strength of evidence, which is especially compelling to big donors;

the independent recommendation, which looks particularly credible and removes the perception of any ulterior motive;

a willingness to maximise (for example by focussing on regular or legacy donors);

the freedom to choose which of the three organisations they promote, depending on who they are talking to.

Putting your money into fundraising, rather than just giving it directly, does impose additional costs on the donors you inspire, and may '

' gifts to other charities. However, the logic of giving to Giving What We Can's top rated charities is that they make better use of money than most other individuals or organisations. So if you have a fundraising ratio significantly above 1:1, these downsides shouldn't much matter.

You might ask: if fundraising is the best thing to do, why wouldn't AMF, SCI or DtW just spend the money you give them on fundraising? There are many possible answers; in part it might discourage people from donating, if they believe that their money will only be invested into more fundraising, rather than spent on directly helping people. Also, the charities do engage in fundraising activities, both themselves and through external help, but would potentially be ineffective fundraisers, as their efforts are naturally spent predominantly on their work addressing diseases overseas. This is what they are good at, and efforts on their part to raise more fund would take up time and energy as well as money to research the most effective means of fundraising.

 and are willing to help out by having your money spent on effective fundraising, you can therefore easily increase your impact several times over. Just help take the pressure of fundraising off Giving What We Can's top charities by founding or giving to a separate organisation that does it for them.

Getting good at raising money for these other organisations is one of the things GWWC aims to do. Because we aren't concentrating on the ground work abroad, we may be in a better position to do that than the charities themselves. We might also seem more objective in fundraising for them than they do themselves. If you agree these kinds of fundraising organisations could the be the most promising charities out there, you can help out organisations like GWWC or GiveWell by getting involved as a volunteer, or donating to them.

Alternatively, maybe you could start up a fundraising organisation yourself. This isn't actually an impractical plan. Starting up a lean and effective fundraising organisation is difficult, but much easier than building a global team to distribute insecticide-treated bed nets. Any bright and energetic person in a rich country who went and received the necessary training would have a decent shot at getting such an organisation off the ground, and by doing so, you will be using your skills where they can help Giving What We Can's charities the most, whilst leaving them to do what they do best.

Learn about how to fundraise. For a popular introduction to learning to sell, check out 

. For evidence-based advice on raising money for charity, we recommend 

There are lots of ways to fundraise. Think about which methods might suit you best given your skills and connections. The highest average fundraising ratios are for 

Test it out. See how much you can raise per hour. And how much could this approach be scaled?

Create a business plan and raise money from effective givers.

If you would like to discuss the first steps required to make this happen, and how you could coordinate with others already taking this approach, including our sister organisation 

How to  create the world's most effective charity

Krisztina Csortea

Today is the last day you can vote on which topics you want AidGrade to cover next! It's your chance to steer research towards issues you think are important. There are roughly 40 options and you can choose three, AidGrade plans on covering 20 of them. The potential research areas include everything from micro health insurance to rural roads. You can find the survey 

And why should you vote? If you are reading this blog, you most likely care about effective aid. AidGrade, like GWWC, evaluates and recommends international development programmes on the basis of effectiveness. You can read more about what AidGrade does 

. Helping AidGrade select new topics is a great opportunity to bring more attention and donations to development issues you care about!

Last chance to have your say on AidGrade

Julia Wise

Economists love to think about tradeoffs (or opportunity costs, as they call them). Any money we spend can't be spent on something else, so if I use $2.50 to buy a strawberry milkshake it means I'm not using that $2.50 to get the chocolate one or the mint chocolate chip one.

That's pretty easy to think about. But it also means I'm not getting a bus fare, a light bulb, or anything else with that $2.50. And if I buy that strawberry milkshake, according to standard economics it means there's nothing else in the world I would rather buy with that money.

I don't think we're usually that rational.

For one thing, it's unpleasant to think about negatives. We like to think about what our money 

 get us, rather than the infinite variety of things it 

 get. Also, there are so many alternatives that we can't really consider them all every time we spend money.

I once saw a flippant proposal that we draw people's attention to this in a gruesome way by labeling all prices in "Dead Child Currency". If it costs $800 to save a child's life, each $800 spent on anything else . . . you get the idea.

I used to make myself think that way. Before I parted with any money, I'd ask myself what it could do for a woman in Africa. (It doesn't have to be her, but that's who I always imagined.) Did I value my new jeans more than her month's groceries? More than her children's vaccinations or school fees? Could I make that tradeoff?

Sometimes I made it and felt awful afterwards. After spending $2 on a caramel apple in the fall of 2008, I had one such episode of weepy regret that was the last straw for Jeff. He decided that part of his income would go to a spending allowance for us both which could not be given to charity. For several years now this is where our mandolin strings, birthday presents, clothes, vacations, and milkshakes have come from. It's also the source of non-optimal donations we make to public radio, etc. It's not a large budget by American standards, but it's made for a lot less angst.

I recently met a young man who was seriously thinking these things over. "But isn't it right to think about the tradeoffs?" he asked. I think it's good to go through a period of thinking that way. Just like when you live in another country for a while you start being able to understand prices without converting back to your own currency, when you start thinking about all your spending in Vaccination Currency or Mosquito Net Currency it becomes habitual. Your spending habits can't help but be affected.

I also think there's only so much grief we can carry. I cannot go the next 70 years counting dead children on every receipt. I would break.

So my advice is to spend a while really noticing that tradeoff. Notice whether you really do value the milkshake more than a child's vaccination. And then, after a time, make yourself a budget that reflects those values. Set aside money for unnecessary things that make you happy. Do what you think will nurture you to age 100 as a generous and strategic giver. Because that, in the end, is what will help the most people.

Tradeoffs

Giving What We Can

When I started volunteering for Giving What We Can, the other members had to explain to me how Giving What We Can works. What it does is clear enough - evaluating charities and inspiring people to donate to the most effective ones, so that we save the most possible "quality adjusted life years." But how? How does it work? To meet such a precise and ambitious a goal, some rather complex things need to happen.

Research is that most mysterious part of Giving What We Can's workings. There, our quantitative-minded members use their analytical and data modelling skills to advise us on where, and how, we should give. (But our impact also depends on the energetic Communications team, who do their best to get the word out; and the Operations team, who stay on top of the legal side of things.)

We are running the September internship programme to let you see for yourself how a charity dedicated to effective giving operates, and to enable you to take part. In this post, you can read some statements from our former research interns about what they did - and why it was awesome.

I got very insightful advice, derived directly from experience, on everything from technical mathematical details, to methods in economic forecasting, to the physics of climate change, to running a successful social campaign.

Edward Higston, currently an Oxford student, explained:

I reviewed Giving What We Can's research on Polio eradication and on water and sanitation. For polio, I concluded that given the uncertainty of success even with large amounts of extra funding ... meant that the expected cost benefit ratio was probably below our current recommended charities and there would be lots of uncertainty

Ed also concluded that currently there are no water and sanitation charities that are as effective as our top recommended ones. Alright Edward, so what we've been doing is the right thing to do!

I worked on estimating the cost-effectiveness of climate change interventions. This was a fascinating project, and a really good introduction to the complexities faced by researchers at Giving What We Can and other cost effectiveness/forecasting research groups.

This was helped a lot by the sharing of expertise from a number of the senior members of the group, especially given the diversity of their backgrounds - I got very insightful advice, derived directly from experience, on everything from technical mathematical details, to methods in economic forecasting, to the physics of climate change, to running a successful social campaign!

Brendan confirmed Giving What We Can's policy on climate change charities, demonstrating that at the moment they are not as effective as our top recommended ones.

But it's not all about research, as he says - it's about being part of the team and of the wider Giving What We Can community. We are for cooperation and good times above all. Brendan continued:

It was just great to work and hang out with a really nice bunch of people who shared similar goals and values. It's good to be reminded and inspired that more responsible living does not really require sacrifice, just a little more care.

Callum Calvert from the University of Warwick, who worked researching the effectiveness of vaccine charities, said:

I really enjoyed and learned a lot from getting to spend time with people who think about altruism pragmatically and who have less bias to particular causes. I think there would be a lot of students who would find this really refreshing.

Similarly, for Ben Clifford from Warwick, the most important aspect was "

being surrounded by inspirational people, finding out how Giving What We Can operated and getting to meet the team

I consider Giving What We Can to be one of the most exciting third sector organisations of the moment; to gain a full insight into its inner workings was a fantastic opportunity.

So if you do the research internship this September, you can expect some hardcore maths, and some good company. Same for Communications and Operations interns - minus the maths (but it's still some intense work). If this sounds like your kind of thing, do consider 

The September Internship, Part 2: Our former research interns talk about working at Giving What We Can

Roxanne Heston

On December 14, 2012, 26 innocent people - 20 children and 6 adults - died at the hand of a mass shooter at Sandy Hook Elementary School in Newtown, Connecticut, United States. (1) This tragic incident, widely recognized as the second deadliest of its kind in the U.S., seems to many to be part of an increasingly widespread trend. (2) A movement has since begun to address the accumulating shootings, with demands for increased gun registration restrictions, tighter school security, and further restraints on firearm possession. These lobbyists – parents, administrators, and common citizens alike – have fought and continue to fight for the protection of themselves and one another against this recurring threat. (1)

But while, on December 14, 2012, approximately 3,000 other innocent children died to a remorseless killer, they passed with little recognition or advocacy for reform on their behalves. These children, living in sub-Saharan Africa, lost their lives to malaria, a disease barely present in the developed world, even less so a common cause of mortality. (3) The children lost in Connecticut, United States and those lost in Kinshasa, Congo or Luanda, Angola were not so very different from one another; they had dreams and aspirations for the future, did nothing to provoke their demise, and belonged to loving families who grieved at their needless deaths.Then why, might one ask, did the former incident claim headlines while the latter, far more devastating in numbers and frequency, pass un-hyped? That is, sadly, a rhetorical question, for we accept that the nature of news is to report on new and shocking occurrences, of which this manner of death is not one. We have become so inured to death by hunger or disease in underdeveloped countries that not only do we, as a general populace, take little heed of its enduring nature, but even concoct justifications and sweetened images to mask the inconceivable reality. While we may be able to empathize with a fear of guns, we can only loosely sympathize with fears of water contamination or lives of destitution. Just because the loss of young lives in Kinshasa or Luanda is not broadcast on the news does not make their demises any less pressing or tragic; in fact, it makes them more so because they pass under the public’s radar. If we can put aside our empathetic notions and remind ourselves that every innocent life, regardless of geographic affiliation, is equally worthy and, ideally, potentially savable, utilitarians will find that their sentiments are best fulfilled by focusing on medical attention in underdeveloped nations, instead of just on those threats that hit closer to home.

One should not be surprised to hear that in the high-income areas of Asia Pacific, Western and Central Europe, Australasia, and North America, the death toll of infants is so low as to be negligible by international standards. In these regions the top causes of adult mortality are cardio and circulatory diseases, (4) namely ischemic heart disease, the reduced blood supply caused by, to be unscientific, unhealthy diets and old age. (5) These diseases account for about one-third of most-developed country (MDC) deaths, approximately twice the rate seen in less- and least-developed countries (LDCs). (4) Globally, deaths before the age of four are some of the most frequent, especially in South Asia and sub-Saharan Africa. Within the first month of life, over two million babies die each year to neonatal disorders like preterm births and Neonatal Encephalopathy. Treatable in a hospital with incubation and/or medication, (6) these disorders kill less than one percent of MDC babies, a small number compared to the near five percent statistic for LDC nations. If an infant manages to live past childhood, it again faces another serious threat in its young adult life: HIV/AIDS. Spiking in risk around an adult’s early- to mid-30s, the virus causes 40 to 50 percent of deaths in many areas of sub-Saharan Africa, and as many as three-fourths of deaths in the Southern region. (4)

Despite their truth, listing these somewhat expected statistics is pointless except for effect, for even the least service-minded among us seem to be familiar with the disparity between regions and nations on death tolls. As developed nation citizens, it is easy to undervalue the caustic impact of preterm births and HIV/AIDS in LDCs, for their implications there far from equal those of our relatively resource-abundant societies. Not only are these conditions lower risk where we live but they also have mitigated symptoms. Ischemic heart disease can be greatly prevented with a less-fatty diet and fought with aspirin. (7) Diarrhea, accounting for about 12,600 deaths daily elsewhere, (8) is a problem easily remedied with antibiotics, water, and time in a developed nation. (9) These and many other “annoyances” of our developed communities superficially pale in comparison to the publicized incidents of death via plane crash or bombing which, fairly protected against death as we are, make us fear for our own safety while we easily estrange ourselves from the seemingly innocuous issues that run rampant in poorer areas. (4)

We know and expect there to be a lot more deaths in LDCs, in numbers as well as in percentage of their populations, than in MDCs. We often hear about the benefits and cost-effectiveness of saving lives abroad – less than a dollar (64 pence) for a measles vaccination (10) or pneumonia antibiotic, about 50 cents (32 pence) for a Neonatal Tetanus vaccination, etc. (11). The purpose here is not to belabour this point but to emphasize the need for the paradox of acting upon this highly sentience-based cause while separating one's emotions from the decisions made to do so, to keep the trees of local illness and gun violence from obscuring our view of the forest of international woes. While personal memories and animal nature guide us to “look out for our own,” our “own,” as recently redefined by a now-globalized society, reaches far beyond tangible boundaries, a change that should be reflected in the way in which we give.

Fitzgerald, Jim, Pat Eaton-Robb, Samantha Henry, Pete Yost, and Michael Melia. "Sandy Hook Elementary School Shooting: Newtown, Connecticut Administrators, Students Among Victims, Reports Say." Huff Post Crime. The Huffington Post, 14 Dec. 2012. Web. 18 Jan. 2013.

Walker, Jesse. "Are Mass Shootings Becoming More Common in the United States?" Reason.com. Reason Foundation, 17 Dec. 2012. Web. 18 Jan. 2013.

"About Malaria." Johns Hopkins Malaria Research Institute. Johns Hopkins Bloomberg School of Public Health, n.d. Web. 20 Jan. 2013.

Rogers, Simon. "How Do People Die? Global Mortality and Causes of Death Visualised." The Guardian. Guardian News and Media, 13 Dec. 2012. Web. 20 Jan. 2013.

"Ischaemic Heart Disease." ScienceDaily. ScienceDaily, n.d. Web. 01 Feb. 2013.

"Neonatal Encephalopathy." Neonatal Handbook. The Royal Children's Hospital Melbourne, n.d. Web. 01 Feb. 2013.

"Ischemic Heart Disease : Treatment, Causes, Symptoms & Prevention." SRS Pharmaceuticals Pvt. Ltd. SRS Pharmaceuticals Pvt. Ltd., n.d. Web. 25 Jan. 2013.

Staff, Mayo Clinic. "Diarrhea." Mayo Clinic. Mayo Foundation for Medical Education and Research, 26 June 2010. Web. 25 June 2013.

Guerrant, R. L., J. M. Hughes, N. L. Lima, and J. Crane. "Diarrhea in Developed and Developing Countries: Magnitude, Special Settings, and Etiologies." Diss. University of Virginia School of Medicine, 1990. Abstract. National Center for Biotechnology Information. U.S. National Library of Medicine, n.d. Web. 25 Jan. 2013.

"Where Does My Donation Go?" American Red Cross. Central and Northern Michigan Region, 29 Nov. 2010. Web. 04 Feb. 2013.

"AFRICA: 28 Days to save a Life." IRIN. UN Office for the Coordination of Humanitarian Affairs, 16 June 2009. Web. 04 Feb. 2013.

Forest for the Trees

Carolina Flores

Antibiotics have been a major driving force in the reduction of incidence of infectious diseases, and therefore in the development of living standards all over the world. However, bacteria are capable of adapting and developing resistance to antibiotics in a short time, which means that new drugs are constantly necessary to keep diseases from spreading. In the past few years, in large part due to misuse of antibiotics, the rate at which they become obsolete has greatly increased. This is aggravated by big pharmaceutical companies leaving or radically reducing attempts to discover new drugs to place in the market, and genomic research failing to deliver new products. This is a problem that needs to be tackled on a wide scale, involving cooperation between business, government and research institutions.

Consider for a moment how deep and wide-reaching the consequences of lacking antibiotics would be. Obviously, epidemics would rise and once again kill millions of people, severely impairing any chances of social or economic development. Tuberculosis would again spread (this is particularly worrying: the World Health Organisation estimates that, between 2000 and 2020, it will infect one billion people and kill 35 million). Pneumonia would once more become a common cause of death, particularly amongst older people. Sexually transmitted diseases would become much harder to cure, causing a number of serious health problems including ectopic pregnancies and a rise of infertility. Organ transplants - or even a surgery as commonplace as removing a burst appendix - would become virtually impossible. (Boseley, 2010, 1)

This apocalyptic scenario – returning to the situation we were in during the pre-antibiotics era, only with a much higher population concentrated in smaller spaces, (which facilitates the rise in epidemics) - might not be far away if nothing is done to avert it. In 2004, it was estimated that over 70% of pathogenic bacteria were resistant to at least one of the current available antibiotics. A number of ‘super bugs’ – resistant to most of the clinically used antibiotics – have also emerged. For instance, S.aureus, a bacteria which has developed resistance to methicillin, is estimated by the Infectious Disease Society of America to be responsible for half of the hospital-associated infections, killing 100 000 people a year in USA hospitals alone. (Demain, 2009)

How has this situation come to be? As bacteria evolve and adapt to changes in the environment, it is no surprise that new antibiotics are regularly needed. However, in the last few decades, the pace at which they adapt has become much faster, and ‘super-bugs’, resistant to most antibiotics, have become more common. This is related to misuse of antibiotics driven by economic reasons. Over half of the antibiotics used in the world are not used to cure disease, but in animal feed, because they work as growth promoters and make it possible to avoid the spread of diseases in conditions in which many animals are kept in a small space. (McVeigh, 2012) This means that we are daily being fed with antibiotics – and unaware of this fact.

To aggravate the issue, since the 90s, most of the big pharmaceutical companies have either completely abandoned antibiotic development (for instance, Roche, Merck and Abbott) or significantly cut down their investment in the area. Instead, they have invested in creating drugs for chronic diseases, which, as they need to be taken for extended periods of time, provide a much better revenue stream than antibiotics, used in short treatments. In addition, regulatory requirements for new antibiotics have become much stricter, greatly increasing the cost of their development. In particular, in the clinical trials phase, their patents last a relatively short time, and new drugs are often reserved for special cases. All this has increased the cost of inventing new antibiotics, making it less appealing than it once was from a business perspective. (Ragnar Norby et al., 2005)

It seems then that economic factors and the drive for profit are behind what may come to be a very serious problem worldwide. To avoid collapse in healthcare, we need to act on the causes of the problem.

First of all, it would be important to regulate the use of antibiotics which are medically important to cure human disease as growth promoters in animal feed (McVeigh, 2010), and also to enforce stricter guidelines on prescription. This could potentially slow down the appearance of ‘super-bugs’, but it doesn’t tackle the problem of lack of production of new antibiotics.

To do so, the main players in this problem – big pharmaceutical and small biotechnology companies, governments and hospitals, and research centres and universities - must be targeted. Better communication between them – for instance, cooperation between research groups and pharmaceutical companies to make the production of new antibiotics cheaper and faster – is an important factor. It may also be important to research if the legal requirements for putting new products in the market can be reduced in a way that makes that process cheaper for companies while keeping it safe for patients. (Ragnar Norby et al, 2005)

In the USA, the IDSA has suggested changes in legislation, such as patent extension, and measures such as tax incentives, to encourage the production of new antibiotics. (Ragnar Norby et al, 2005) Others (Boseley, 2010, 2) have suggested that the key step is to reward hospitals and drug companies for what they do to keep antibiotics effective, for instance by taxing drugs to reduce prescription and investing the revenue into the production of new antibiotics.

This is a very complicated issue, for it involves a large number of organisations and economic factors need to be considered in conjunction with human impact. It is clear, however, that this is an urgent problem whose solution will require a global plan involving investment, cooperation, and regulation. Further, it illustrates that the drive for profit found in business must be combined with a serious and responsible consideration of its human and social impact.

BOSELEY; Sarah, 2010. Are You ready for a world without antibiotics?

 The Guardian (online), 12 August 2010 (28th February 2012) 

BOSELEY; Sarah, 2010 (2). A Radical Plan to Save Antibiotics.

 The Guardian (online). 7 September 2010. (28th February 2012) 

DEMAIN, A.L., SANCHEZ, S., 2009. Microbial Drug Discovery – 80 years of progress. The Journal of Antibiotics. 62, 5-16.

McVEIGH, K. 2012. Scientists: Overuse of Antibiotics in Animal Agriculture Endangers Humans The Guardian (online)

, 19 September 2012 (28th February 2012) 

OVERBYE, K.M., BARRETT, J.F., 2005. Antibiotics: Where did we go wrong? Drug Discovery Today, Volume 10, Issue 1, 1 January 2005, Pages 45–52

RAGNAR NORBY, S., NORD, C.E., FINCH, R. for the European Society of Clinical Microbiology and Infectious Diseases (ESCMID), 2005. Lack of Development of New Antimicrobial Drugs: a Potential Serious Threat to Public Health. The Lancet Infectious Diseases, Volume 5, Issue 2

 February 2005, Pages 115–119 Available at: (28th February 2012)

A world without antibiotics?

Matt Griffiths

By Matt Griffiths**,** working Pro Bono for Costello Medical Consulting, and Robert Wiblin

In order to understand the impact of any charitable intervention against a disease, it is imperative to have a full appreciation of the scope of the disease burden, both epidemiologically and economically. By 'scope of the disease burden', I am not only referring to a standard static measurement of the prevalence, treatment costs and morbidity; we also need to factor in the dynamic nature of the disease itself. For instance, imagine a choice between two treatments: programme A, which provides direct treatment to 100,000 sufferers of a poorly transmissible disease, or programme B, which cures just 10,000 patients suffering from a similarly painful disease that is renowned for its high transmissibility. The immediate impact of programme A will be higher, but ultimately programme B may represent the more cost-effective option, especially if further cases are hard to treat.

Without factoring in the contagiousness of a disease, we will probably underestimate the effect that curing someone with a given disease may have. [A] Furthermore, we won't appropriately prioritise highly contagious diseases.

One way of capturing the effect of the contagiousness of a disease on the impact of a cure/treatment might be to develop a quantitative measure unique to each disease, here termed the 

. When I started searching I was hopeful that such a measure would exist amongst the epidemiological literature. The question is, after all, important for prioritising the provision of healthcare. My search was, admittedly, not systematic, but after exploring a number of search terms based around "contagiousness/transmissibility" of disease on Google and PubMed, I was disappointed to find nothing of obvious application to the problem.

I then decided to consider another phrasing of the problem: '

if someone with the disease is spontaneously cured, how many fewer people will catch the disease who otherwise would have?'

 This strongly reminded me of another measure I had heard of: the basic reproductive number, referred to as R

The basic reproductive number is defined as "the average number of secondary infections caused by a single infectious individual during their entire infectious lifetime". R

 must be greater than 1 for a disease to persist in the population. It would certainly seem to be a promising tool for modelling contagiousness of different diseases, not least because this measure is well studied and because indicative values are already documented for a number of diseases (e.g. measles ~12-18

, HIV ~2-5 [among male homosexuals in England and Wales

]). So, can these values be used to directly generate contagiousness multipliers for comparing different diseases, and thereby allow us to determine the effect of a charitable intervention in terms of the total number of disease cases avoided over a given time period?

 is quite an imperfect measure. The basic reproductive number is not a characteristic of the disease alone, but of the disease in a specific population at a specific time. In particular, it is not possible for a disease to indefinitely have an R

 far above 1, because eventually the number of people with the disease would exceed the entire population! There are several ways a disease with a high R

 tends to see its basic reproductive number decline over time:

Someone who already has a disease can't 'double catch' it

Someone who has already had a disease often dies or becomes immune

We, as humans, respond and contain such diseases with artificial interventions.

Over the long run, a disease should reach an equilibrium in which the rate of new cases equals the rate at which people are cured. If this wasn't the case, curing a single person of a disease with a high R

 would have an enormous impact in the long run!

 for a disease in a given time and place, this value would still take some interpretation for our purposes. R

 represents the total number of people who are infected with a disease by a contagious individual, and so describes the value of curing someone before they become infectious. This is therefore a useful number when evaluating interventions for disease prevention, but not treatment. Many charities may not cause people to be treated who otherwise wouldn't have been, but instead may cause them to be treated earlier. In this case what matters is the 'rate of transmission per day', not the total number of people infected. If we know the average length of time that an infected person remains contagious, we can derive this number. [B]

Nonetheless, the factors influencing contagiousness of a pathogen are many and interacting: pathogen and host characteristics as well as overarching population dynamics all play a role, and are likely to differ between diseases. It is not practical for us to consider all of these factors individually and so it seems to me that a contagiousness multiplier must be derived from epidemiological measures that already exist. The basic reproductive number has provided a good starting point, and whilst the caveats associated with the use of R

 limit its direct application as a contagiousness multiplier, the exploration of this tool has certainly highlighted to me some important points for consideration. I hope that in my further research the potential indirect applications of R

[A] At least if we are using micro-level studies, rather than data looking at the prevalence of a disease across an entire region.

[B] A disease with a low probability of transmission, but a long infectious period, might have the same R

 as a highly contagious disease with only a short infectious period, because the R

Blog

How to create the world's most effective charity

Last chance to have your say on AidGrade

Tradeoffs

The September Internship, Part 2: Our former research interns talk about working at Giving What We Can

Forest for the Trees

A world without antibiotics?

The contagiousness modifier

Film Review: "I AM"

Announcement – the September Internship Programme

Why I give