Pandemic Preparedness: Are We Ready?

Imagine the scenario: Tens of millions dead, many of them young adults struck down in their prime. Hospitals and emergency rooms overrun with the sick and seriously ill. An already faltering economy on the verge of collapse due to closures of businesses, services and public transportation — not just in certain cities, states or regions, but globally. While these borrowed-from-the-box office images seem surreal, for many working behind the scenes of the H1N1 (swine) flu scare, they represent a very serious threat. Our society has been overdue for a pandemic; it wasn’t if, but when. And although predicting a pandemic is highly speculative at best, what we do know is this: Historically, pandemics have started with relatively mild new flu strains in the spring, only to return with a vengeance in the fall and winter when viruses peak.

Lessons Learned

While not all new strains with pandemic markings reach their potential (many begin in the spring only to fizzle out), the world has experienced three other influenza pandemics to date. And while this number may seem low, pandemics take a heavy toll on society, shutting down economies, creating panic and, oftentimes, killing millions. So, when a new outbreak occurs, the World Health Organization (WHO) and government entities quickly step in at the epidemic, or pre-pandemic stage, to assess pandemic likelihood, minimize the spread of disease and inform and educate the public about the likelihood of another pandemic in the making. Though this level of attention causes widespread panic, the lessons of the past coupled with the short window of time between spring and fall provide a much needed period for preparedness. With all of the uncertainties surrounding this current H1N1 pandemic period, the blessing is in the times we live in. It is a new world since the previous pandemics, with instantaneous communication, advances in vaccine capability and production, and the availability of antivirals to minimize illness and mortality rates.

From Epidemic to Pandemic

The outbreak of the H1N1 flu virus has brought considerable attention to the terms epidemic and pandemic. Despite the statement by Dr. Richard Besser, MD, previous acting director for the Centers for Disease Control and Prevention (CDC), that it means less what we call this new flu outbreak than what we do about it, many are wondering what the difference is between the two terms.

An epidemic occurs when new cases of a disease appear during a given period at a rate that substantially exceeds what is expected. When an epidemic gets out of hand, it’s called a pandemic. Briefly, the requirement for a pandemic classification is the disease is so new that the population has no antibodies to protect against it. A pandemic has two nuances: geographical spread and incidence rate. A pandemic spreads rapidly, can become global and can be extremely deadly.

History of Flu Pandemics

The flu pandemic of 1918, known as the Spanish flu, was the deadliest outbreak of all time. It was particularly prevalent in young men at military training camps and on troop ships for World War I. When our military traveled overseas, they took the flu virus with them. It became known as the Spanish flu because of the press it received in that country during the war. While the Spanish flu was an H1N1 strain, it was an avian flu and different from the current H1N1 flu strain.

That pandemic struck mostly healthy young adults, although it was also particularly severe for the very young (those younger than 5 years) and very old (those older than 65 years) whose mortality is most vulnerable to the virus. Experts estimate that between 30 million and 100 million people died from the Spanish flu, but 50 million is the most often quoted figure. To put this in perspective, the Spanish flu killed more people than all previous outbreaks of the plague (Black Death) and more than the number of people who died in World War II.

In 2008, a study conducted by scientists at the National Institutes of Health (NIH) determined that most of those who died from the 1918 pandemic succumbed to bacterial pneumonia after their lungs were weakened by the influenza virus. “In essence,” says study co-author Anthony S. Fauci, MD, “the virus landed the first blow, while bacteria delivered the knockout punch.”¹

A second pandemic occurred in 1957. Known as the Asian flu due to its origin in China, it was an H2N2 strain. During this pandemic, there were two waves: The first affected mostly children and the second affected the elderly. Approximately two million individuals around the world died from the Asian flu.

The next pandemic was in 1968 and was called the Hong Kong flu. While the first occurrence of this flu was detected in Hong Kong, it spread globally and killed approximately one million people, mostly the elderly. This pandemic is considered to be the mildest of all.

Flu Pandemic Scares

While there have been many flu outbreaks that have come close to being classified as pandemics, the most memorable (especially in light of the current outbreak) was another swine flu in 1976 that began in New Jersey. In that outbreak, hundreds of soldiers at Fort Dix fell ill. Of those, there were 13 severe illnesses and one death: a healthy soldier who died within 24 hours of contracting the flu. When two additional cases were reported in Virginia, the nation became alarmed and the federal government created an emergency inoculation program under which 40 million Americans were given vaccines. The inoculation program was discontinued when it was determined that several hundred of those vaccinated had developed Guillain-Barré syndrome. Fortunately, not even an epidemic developed.

A more recent outbreak occurred in 2006, and was known as the bird flu. That flu, an H5N1 strain that originated in parts of Asia where people and poultry live in close quarters, spread globally. Particularly alarming about this virus was the overall mortality rate of approximately 60 percent. That is far more lethal than the worst pandemic, which had a 2.5 percent to 6 percent mortality rate. The seasonal flu has only a 0.1 percent mortality rate, causing approximately 36,000 deaths annually. The good news about the bird flu was that it didn’t spread easily from one person to the next, making it easier to control. To combat the bird flu, tens of millions of infected birds were killed.

While many outbreaks of new flu strains have been kept at bay, thus preventing an epidemic or pandemic, there is still a threat potential. In the instance of the H5N1 strain, it is possible for one minor mutation to remove the barrier to transmission, thus causing it to spread from person to person more quickly.

Identifying a New Threat

How is it determined if a new flu virus strain is a threat? There are two primary characteristics of a disease: pathogenicity and virulence.² If a virus readily causes disease and is easily spread, it is considered pathogenic. The severity of the symptoms from the virus determines its virulence.

In the 1918 Spanish flu pandemic, the virus spread easily from person to person and the symptoms were severe, resulting in millions of deaths, which means it was highly pathogenic and highly virulent. On the other hand, the H5N1 bird flu, while it was highly pathogenic with a high mortality rate, it spread poorly from person to person, making it mildly virulent.

When a new virus arises, these characteristics are identified by health experts to determine the threat potential.

The New Strain: H1N1 Flu

The newest flu strain, H1N1, is causing alarm worldwide, and the CDC, WHO and other health departments are taking steps to educate and protect populations, as well as diagnose outbreaks.

H1N1 flu occurs when people handle (but not eat) infected pigs, though the incidence of infection passing from person to person is growing. This new flu is a mixture of swine viruses and elements of human and bird flu. It has symptoms very similar to the seasonal flu, with severity also ranging from mild to severe. Thankfully, the seasonal flu season is pretty much over, and the B strain was the primary strain at the end of the season. That allows us to assume at this point that anything that tests positive for influenza A is the H1N1 flu, says Paul Glezen, MD, Baylor College of Medicine, Houston, Texas.

Only the CDC and state labs can formally confirm the infection of H1N1 flu. In May, the CDC began distributing a PCR diagnostic test kit to detect the H1N1 virus. The test kits were shipped to all states in the U.S. and Puerto Rico, as well as internationally. This increase in testing capacity has resulted in an increase in the number of reported confirmed cases in this country, which will provide a more accurate picture of the burden of disease.

Equally important to diagnosing the H1N1 flu is determining how best to protect people from it. “The swine flu seen in the 1930s is very similar in structure to the flu pandemic of 1918,” says Glezen. “Right now, we are trying to determine how different is this strain.” A pig has a short lifespan, which doesn’t leave a lot of time for mutation, explains Glezen. “We need to know if we have any pre-existing immunity to this flu. Many of us in 1976 had the swine flu vaccination. Do we have any antibodies to this strain? Maybe the answer is we have none. That would be a bad pandemic.”

An internal report prepared by researchers at the CDC’s Influenza Division and Immunization Service Division, may provide some insight about antibodies to the strain. Titled “Lessons Learnt from the 1976 Swine Flu Outbreak,” the research looked at whether prior infection or vaccination with the human H1N1 virus offers protection against the swine flu.³ Researchers found that prior antibodies from circulating H1N1 strains at the time of vaccination in subjects were critical for a satisfactory immune response to vaccination with the 1976 swine influenza vaccine. Those subjects who had prior experience from circulating strains had good serological response after a single dose of vaccine, while those who did not have prior experience would require a second dose to achieve adequate immunization.

Based on the findings of this report, Luke Noll, a vaccine specialist for FFF Enterprises, Inc., Temecula, Calif., says “it may be likely that at least some of the population who received the 1976 swine influenza vaccine, or who may have experienced circulating human H1N1 strains, may have a better immune response after a single dose of a newly created H1N1 vaccine, whereas others will likely require two doses of vaccine to achieve a satisfactory immune response.”

Planning for an Influenza Pandemic

Researchers at the National Institute of Allergy and Infectious Diseases (NIAID) recommend that preparations for diagnosing, treating and preventing bacterial pneumonia should be among the highest priorities in influenza pandemic planning.⁴ Right now, the CDC and WHO are continuing to monitor on a daily basis the impact the H1N1 flu is having on the U.S. and international populations. According to Dr. Anne Schuchat, director of the National Center for Immunization and Respiratory Diseases, H1N1 flu “activity seems to be declining in the nation as a whole, but there are some areas where illness is ongoing.”⁵ In the U.S., cases are confirmed in all 50 states, and the global situation is increasing. With the southern hemisphere now in its flu season, the CDC and WHO are keeping a close watch on that region to guage what effect the H1N1 flu might have on regions where the flu season occurs in the fall.

Younger people between the ages of 5 and 24 years are those who have been most affected by the H1N1 flu. This is different than what is normally seen with seasonal influenza during which the elderly have the highest hospitalization rates.⁵ Tests have revealed what scientists suspected was the reason for this: People in their 60s and older have signs of greater immunity to the H1N1 flu virus because they have been exposed to other viruses in the past that are more similar to the H1N1 virus than recent seasonal flu viruses. However, it is still too early to tell how safe older people actually are from the new infection.⁶

Because the H1N1 flu has spread widely, the WHO has upgraded the pandemic flu stage alert from phase 5 to phase 6 — a full pandemic. Yet, Schuchat cautions that designation of a pandemic alert level only suggests that the virus has spread widely, and not that the virus is more severe than has been described in news reports.⁵ “The phasing at WHO is an indicator of spread and not of severity,” explains Schuchat. In addition, she adds, “the pandemic alert level [is] a reflection of epidemiologic changes in other parts of the world, not here in the Americas where we … already have had extensive community spreads.”

The first steps have been taken to develop a candidate vaccine virus for the H1N1 strain. According to Schuchat, the CDC has provided that virus to a number of manufacturers to produce pilot lots of vaccines that can be tested to see whether they would be safe and provide clinical protection. However, she said, the decision about whether or not to use a vaccine and how to use it has not and won’t be made until more information is known about the disease and how the vaccine performs in clinical testing. Those are the intensive efforts that the CDC plans to make over the summer months. In the meantime, whether the vaccine is needed or not, the CDC has begun efforts to plan for immunization.

“At this time,” says Noll, “the research and study by the CDC is ongoing, and the experts will determine the path that we must take to remain healthy from seasonal influenza and/or this novel H1N1 strain this upcoming season. Whether we need to receive one, two or three vaccinations this upcoming season is yet to be decided. Surely, we will know the answer soon.”

Only Time Will Tell

It is possible for an influenza pandemic to unfold in a manner similar to the outbreak in 1918, say researchers at the NIAID.¹ But, scientists have learned a lot over the years from previous pandemics. And, as witnessed by the recent actions by the various government agencies, the U.S. is prepared to act aggressively and to take bold action to minimize the effect on people’s health. So, for now, this pandemic is not out of hand. But, as previous influenza outbreaks have shown, it is possible to see an initial outbreak early on, only to be followed by a more serious outbreak of that strain when flu season strikes. It is imperative, then, that we be prepared.