The effects of vaccination on public health
I saw a link that’s been making the rounds via Twitter and Facebook lately, from the Council on Foreign Relations. They have put together an interactive map that allows you to focus on any geographic region and visualize reported outbreaks of a variety of infectious diseases that are currently highly preventable by vaccination. The map quickly shows some obvious trends–various diseases show regions where they are more prevalent, but the regions follow political lines, not naturally occurring geographical lines. For instance as seen in this graphic, diphtheria (whooping cough) and mumps outbreaks are prevalent in the United States, but are not significantly reported elsewhere in North America. Measles outbreaks occur with extreme regularity in Western Europe, but very little in Eastern Europe. Rubella (German measles) occurs in Eastern Europe and Japan.
A disclaimer on the Intro page of the website states its purpose; to promote awareness of a preventable global health issue. The site also allows you to download and view the dataset used to compile the maps. Interestingly, outbreak reports are not only taken from governmental public health agencies, but also from media reports, and indeed a spot on the webpage allows visitors to submit links to outbreaks that they might have come across. I suspect this practice leads to maps that might be useful from a broad educational standpoint, much as the site disclaimer suggests, however it is probably not appropriate for a true epidemiological estimate of the diseases in question from a global standpoint. For instance, according to this summary at the World Health Organization, the incidence of measles in the Russian Federation appears to be at a rate similar to that found in Spain, and furthermore measles, pertussis, and rubella have been increasing there each year over the past 4 years. Official numbers from the Russian government suggests that vaccination coverage is very good for many diseases, with the reported rate for measles vaccine coverage over 98% of the population. The United States in contrast has around 92% coverage. The rate of disease in Russia suggests several alternative possibilities; the rate of actual vaccine coverage does not accurately reflect the “official” numbers, or that the vaccine is not entirely effective in preventing the disease. The CDC indicates that the current two-dose vaccine regimen is essentially 100% effective in preventing disease due to all virus types.
Measles on its own is an annoying, but not particularly dangerous disease in most individuals. It is among one of the most contagious infectious diseases known however, and can be very easily spread through an immunologically naive population. Furthermore, complications arise in up to 20% of the cases, with a fatality rate in about one in 1000 cases. This fatality rate does not seem very large, however in the context of the number of cases in regions where it is still endemic, many deaths still occur. Because of the high infective potential, and the large numbers of cases worldwide, vaccination remains the best public health choice in this country.