This week, vaccination was in the news with US billionaire Bill Gates and a consortium of western nations pledging $3.7 billion at an international donor conference in London to fund vaccination programs to protect children in poor countries. The Global Alliance for Vaccines and Immunisation aims to extend vaccination programs to children in developing countries by 2015 so they don't have to die of preventable diseases. Gates alone donated $1 billion, more than what most countries contributed.

In a sense, public health officials in the developed world are struggling with the consequences of their own success in the prevention of diseases using vaccines. When most members of a community are vaccinated against a particular disease, the minority who do not receive the vaccination are also protected by a phenomenon called 'herd immunity'.

However, recently there have been outbreaks of measles in Europe and the US because many people are choosing not to be vaccinated. This may be a genuine clash between individual liberty and social welfare. Unlike in the developing world where we continue to witness the onslaught of many vaccine-preventable infectious illnesses, anti-vaccine activists in the developed world may have forgotten diseases like small pox and how they were brought under control.

Small pox had been a scourge for thousands of years. In Nepal, there are temples dedicated to gods that cure small pox. In the twentieth century alone (before small pox was eradicated in 1977) it killed a staggering 300 million people. Today, amazingly, only two tiny vials of this virus exist, one in Siberia and the other in Atlanta.

But micro-organisms have a tendency to behave unpredictably. In 2003 the viral disease SARS (Severe Acute Respiratory Syndrome) scared everyone and departments were created by the World Health Organisation to tackle the problem and try to produce a vaccine, but surprisingly the virus disappeared at the end of 2003. Similarly in 2009 a novel influenza virus, H1N1 emerged in Mexico and threatened a global pandemic and vaccination was strongly recommended, but then the disease appeared to peter out.

Those examples notwithstanding, we should never be complacent about trying to obtain the life-saving vaccines which have helped modern medicine triumph over common infectious diseases still prevalent in countries like Nepal.