Boston, MA - In recent years, health professionals and the general public alike have been acutely aware of the potential ravages that could result from a flu pandemic. Although many people might still recall the pandemics of 1968 and 1957, it is the infamous 1918-1920 pandemic--and the possibility of a recurrence on that scale--that causes the most trepidation.
Strangely, researchers still don't know exactly how many people died from this particular strain of the flu virus in that pandemic, and they know even less about how mortality rates varied in different parts of the world. In fact, most historic information is based on eyewitness accounts and not on statistical analysis. Now, a team of researchers from Harvard School of Public Health (HSPH) and the University of Queensland in Australia have re-analyzed data from 27 countries around the world to estimate both the global mortality patterns of the 1918 pandemic and, based on 2004 population data, how a similar pandemic would affect the world today.
These findings, to be published in the December 23, 2006 issue of The Lancet, show that mortality rates for the 1918-1920 pandemic were disproportionately high in communities where per capita income was lowest. If the same pandemic were to occur today, approximately 96 percent of deaths would occur in developing countries.
In event of a pandemic if you can manage it your best option is total physical isolation. If you can telecommute to work and rarely go shopping or anywhere else with people your odds of getting the flu will be extremely low.
The difference in risk from the lowest to highest death toll regions varied by a multiple of 39 in the 1918 outbreak.
For many decades, published epidemiological literature assumed that mortality rates from the 1918-20 pandemic were distributed fairly equally. A simple population count from that period would lead to the conclusion that about 20 percent of all fatalities occurred in the developed world. "But when you look at the data," said Murray, "that number shrinks to about three or four percent."
The disparities between the developed and developing worlds during this period are striking. For example, in Denmark 0.2 percent of the population succumbed to the flu. In the United States, that figure is 0.3 percent (based on data from 24 states). In the Philippines, the mortality rate was 2.8 percent, in the Bombay region of India, 6.2 percent, and in central India, 7.8 percent, which was the highest rate of the countries and regions analyzed. According to this data then, from Denmark to central India, death rates from the 1918-1920 flu pandemic varied more than 39-fold.
What caused the disparity in death rates? One possibility: nutrition. Poorer people died at higher rates because their immune systems were weakened by malnutrition. Also, in more developed countries perhaps people could better afford to go about their daily activities without coming into close contact with others. Anyone who can afford total isolation can avoid catching a pandemic flu virus.
62 million would die if an influenza virus of similar lethality spread in a pandemic today. Will H5N1 avian flu virus adapt to human spread and cause this scenario to come true? Or will H5N1 even exceed the 1918 strain in lethality? Your guess is as good as mine.
The researchers then took the relationship observed in 1918 between per capita income and mortality and extrapolated it to 2004 population data. After adjusting for global income and population changes, as well as changes in age structures within different populations, the research team estimated that if a similarly virulent strain of flu virus were to strike today, about 62 million people worldwide would die.
The economic disruption would be enormous as people became too sick to work, needed care, and became too afraid to go to work. We need to think ahead about measures that can simultaneously decrease the risk of infection and reduce economic disruption. In event of a pandemic I have argued for a response I call "workplace cocooning" which would be live-in workplace quarantines where people live and work in the same place and never leave their workplace for months until vaccines make human contact safe again. Some would live and work at home and telecommute. Others would get together in workgroups and live and work either in a regular workplace or in a big farm house. Larger groups could live and work together in an otherwise empty hotel (travel would collapse) converted to serve as both offices and living space.
Sailors on ships could stay on ships for the duration and never get off the ships in ports while their ships are unloaded and loaded. Truck drivers could stay in their cabs while the trailers get loaded and unloaded at warehouses by workers who would live in the warehouses and never leave during the pandemic.
The idea is to divide up people into workgroups and avoid contact between workgroups while allowing contact to do necessary collaborative work within workgroups. This model would not work well for every occupation or individual. But enough people live by themselves or in small families that consolidation of groups into combined group homes and workplaces would allow a large fraction of the population to continue working with little risk of infection.