Asian Flu (1956-1958)
The Asian flu was a category 2 flu pandemic outbreak of avian influenza (H2N2) that originated in China in early 1956, lasting until 1958. It originated from mutation in wild ducks, combining with a pre-existing human strain. The virus was first identified in Guizhou province. It spread to Singapore in February 1957, reached Hong Kong by April, and the US by June. The death toll in the US was approximately 69,800, with the elderly particularly vulnerable. Estimates of worldwide infection rate vary widely, depending on the source, ranging from 1 million to 4 million.
Hong Kong Flu (1968–1969)
The Hong Kong flu was a category 2 flu pandemic caused by a strain of H3N2 descended from H2N2 by antigenic shift, in which genes from multiple subtypes reassorted to form a new virus. The Hong Kong flu pandemic of 1968 and 1969 killed an estimated one million people worldwide. Those over 65 had the greatest death rates. In the US, there were about 33,800 deaths.
Potential Impact of A Pandemic
An especially severe flu pandemic could lead to high levels of illness, death, social disruption, and economic loss. Everyday life would be disrupted because so many people in so many places become seriously ill at the same time. Impacts can range from school and business closings to the interruption of basic services such as public transportation and food delivery.
During the 1918 epidemic, entire families became ill. In Philadelphia, a city especially hard hit, so many children were orphaned that the Bureau of Child Hygiene found itself overwhelmed and unable to care for them. As the disease spread, schools and businesses emptied. Telegraph and telephone services collapsed as operators took to their beds. Garbage went uncollected as garbage men reported sick. The mail piled up as postal carriers failed to come to work.
State and local departments of health also suffered from high absentee rates. No one was left to record the pandemic’s spread and the Public Health Service’s requests for information went unanswered. In many communities, quarantines were imposed to prevent the spread of the disease. Schools, theaters, saloons, pool halls and even churches were all closed. As the bodies mounted, even funerals were held outdoors to protect mourners against the spread of the disease. As the bodies continued to accumulate, funeral parlors ran out of caskets and the bodies went uncollected in morgues.
Pandemic Prevention and Control
Pandemics usually come and go in waves, each of which can last for 6 to 8 weeks. In each of the four major pandemics since 1889, a spring wave of relatively mild illness was followed by a second wave, a few months later, of a much more virulent disease. This was true in 1889, 1957, 1968 and in the catastrophic flu outbreak of 1918. The majority of deaths occurred not in the first wave, but later; thus, there may be time to develop an effective vaccine before a second, more virulent strain begins to circulate.
It is impossible to predict when the next flu pandemic will occur or how severe it will be. Wherever and whenever a pandemic starts, everyone around the world is at risk. A substantial percentage of the world’s population will require some form of medical care. Healthcare facilities can be overwhelmed, creating a shortage of hospital staff, beds, ventilators and other supplies. Surge capacity at nontraditional sites such as schools may need to be created to cope with demand.
The need for vaccine is likely to outstrip supply, and the supply of antiviral drugs is also likely to be inadequate early in a pandemic. Difficult decisions will need to be made regarding who gets antiviral drugs and vaccines.
Death rates are determined by four factors:
- Number of people who become infected
- Virulence of the virus
- Underlying characteristics and vulnerability of affected populations
- Effectiveness of preventive measures
A vaccine probably would not be available in the initial stages of population infection, since a vaccine cannot be developed to protect against a virus which does not yet exist. Once a potential virus is identified, it normally takes at least several months before a vaccine becomes widely available, as it must be developed, tested and authorized. The capability to produce vaccines varies widely from country to country; in fact, only 19 countries are listed as “influenza vaccine manufacturers” according to the World Health Organization. It is estimated that, in a best-case scenario, 750 million doses could be produced each year, whereas it is likely that each individual would need two doses of the vaccine in order to become immuno-competent.
Distribution to and inside countries would probably be problematic. Several countries, however, have well-developed plans for producing large quantities of vaccine. For example, Canadian health authorities say that they are developing the capacity to produce 32 million doses within four months, enough vaccine to inoculate every person in the country.
Another concern is whether countries which do not manufacture vaccines themselves, including those where a pandemic strain is likely to originate, will be able to purchase vaccine to protect their populations. Cost considerations aside, they fear that the countries with vaccine-manufacturing capability will reserve production to protect their own populations.
Many nations, as well as the World Health Organization, are working to stockpile anti-viral drugs in preparation for a possible pandemic. Oseltamivir (trade name Tamiflu) is the most commonly sought drug, since it is available in pill form. Zanamivir (trade name Relenza) is also considered for use, but it must be inhaled. Other anti-viral drugs are less likely to be effective against pandemic influenza. Both Tamiflu and Relenza are in short supply, and production capabilities are limited in the medium term. Some doctors say that co-administration of Tamiflu with probenecid could double supplies. Also to be considered is the potential of viruses to develop drug resistance.
Antibiotics and Bacterial Vaccines
As we have seen, many deaths in influenza pandemics are attributable to secondary infection by bacterial pneumonia. This means comprehensive pandemic preparations should include not only efforts to produce new or improved influenza vaccines and antiviral drugs but also provisions to stockpile antibiotics and bacterial vaccines as well.