What is pandemic flu?

A pandemic is a global disease outbreak. An influenza pandemic occurs when a new influenza A virus emerges for which there is little or no immunity in the human population, begins to cause serious illness, and then spreads easily person-to-person worldwide.

Pandemics are not just really bad flu seasons. In fact, pandemics are not seasonal at all and can occur at any time of the year. There is no pandemic flu anywhere in the world at this time.

Is pandemic flu the same as bird flu?

No. The H5N1 virus currently infecting birds and some humans has not mutated into a pandemic-causing strain of influenza virus.

Why are pandemics such dreaded events?

Influenza pandemics can rapidly infect virtually all countries. Once international spread begins, pandemics are considered unstoppable, because the virus spreads very rapidly by coughing or sneezing. Infected people can also share the virus before symptoms appear.

The severity of disease and the number of deaths caused by a pandemic virus vary greatly and cannot be known prior to the emergence of the virus. During past pandemics, attack rates reached 25-35% of the total population. Under the best circumstances, assuming that the new virus causes mild disease, the world could still experience an estimated 2 million to 7.4 million deaths. Projections for a more virulent virus are much higher. The 1918 pandemic, which was uniquely severe, killed at least 40 million people. In the US, the mortality rate of people infected with the virus during that pandemic was around 2.5%.

During a severe pandemic, such as the one that occurred in 1918, there would be large surges in the numbers of people requiring or seeking medical or hospital treatment, temporarily overwhelming health services. High rates of worker absenteeism could also interrupt other essential services, such as law enforcement, transportation, and communications. Because populations will be fully susceptible to a pandemic virus, rates of illness could peak fairly rapidly within a given community and social and economic disruptions would be temporary. They may, however, be amplified in today's closely interrelated and interdependent systems of trade and commerce.

What is the difference between a pandemic and an epidemic?

An epidemic is an outbreak of a disease that occurs in one or several limited areas, like a city, state, or country. Once the disease spreads beyond the borders of several countries and affects many countries across the globe, it is called a pandemic.

What are pandemic alert phases and what phase are we in?

Experts at WHO and elsewhere believe that the world is now closer to another influenza pandemic than at any time since 1968, when the last of the previous century’s three pandemics occurred. WHO uses a series of six phases of pandemic alert as a system for informing the world of the seriousness of the threat and of the need to launch progressively more intense preparedness activities.

The designation of phases, including decisions on when to move from one phase to another, is made by the Director-General of WHO.

Each phase of alert coincides with a series of recommended activities to be undertaken by WHO, the international community, governments, and industry. Changes from one phase to another are triggered by several factors, which include the epidemiological behavior of the disease and the characteristics of circulating viruses.

The world is presently in phase 3: a new influenza virus subtype is causing disease in humans, but is not yet spreading efficiently and sustainably among humans.

Will the H5N1 bird flu virus cause the next influenza pandemic?

Scientists cannot predict whether an avian influenza (H5N1) virus will cause a pandemic. Today, H5N1 is a bird flu. There are no reported cases of sustained human-to-human passage of H5N1. However, as it mutates, it is possible the virus could become capable of passing human to human and then spread very quickly. That is why public health departments are increasing surveillance, monitoring for outbreaks, promoting international cooperation, increasing antiviral stockpiles, and building more robust capacity for vaccine production. These efforts will help protect us no matter what pandemic strain emerges or where.

When will an influenza pandemic happen?

Many scientists believe it is a matter of time until the next influenza pandemic occurs. However, the timing and severity of the next pandemic cannot be predicted. Influenza pandemics occurred three times in the past century — in 1918-19, 1957-58, and 1968-69.

What are the symptoms of pandemic flu?

The symptoms of pandemic flu resemble the symptoms of seasonal flu but may be more prolonged or severe. These symptoms include fever of 100 to 104 degrees, severe and persistent fatigue, dry cough and a feeling of burning in the chest, sore throat, and runny nose. Shortness of breath, diarrhea, vomiting, abdominal pain, and red eyes may also occur.

What age groups would more likely be affected? Are university students likely to be affected?

Many age groups would be seriously affected. The greatest risk of hospitalization and death — as seen during the last two pandemics in 1957 and 1968 and during annual influenza — will be infants, the elderly, and those with underlying health conditions. However, in the 1918 pandemic, most deaths occurred in young adults. Few if any people would have immunity to the virus. University students are likely to be affected.

Is there a vaccine against pandemic flu?

There is currently no vaccine against a pandemic strain of influenza virus. Such a strain would have to emerge before a vaccine could be produced against it.

How much time does it take to develop a vaccine?

The influenza vaccine production process is long and complicated. Traditional influenza vaccine production for the US relies on long- standing technology based on chicken eggs. This production technology is labor-intensive and takes up to 9 months from start to finish.

The flu vaccine production process is further complicated by the fact that influenza virus strains continually evolve. Thus, seasonal flu vaccines must be modified each year to match the strains of the virus that are known to be in circulation among humans around the world. As a result of this constant viral evolution, seasonal influenza vaccines cannot be stockpiled year to year.

The appearance of an influenza pandemic virus would likely require creation of a new vaccine. Large amounts of vaccine cannot be made before knowing exactly which virus will cause the pandemic. It could then take up to 6 months before a vaccine is available and in only limited amounts at first. Research is underway to make vaccines more quickly.

How will vaccine be distributed if a pandemic breaks out?

The federal government will work with manufacturers, distributors, and states, and the states will develop distribution plans at the local level. States are developing and improving plans to distribute a vaccine rapidly. These plans build on experience gained from other emergencies.

In addition, influenza vaccine makers already have systems in place to distribute vaccine. Tens of millions of doses of seasonal influenza vaccine are shipped every year, and during past shortages, vaccine makers have responded to urgent situations.

Fairness in vaccine distribution and use during a pandemic is important. Protecting people at high risk and protecting essential day-to-day services are also important considerations.

What drugs are available for the treatment of pandemic flu and how would they be used?

Antiviral medications are available to help prevent infection in people at risk and lessen the impact of symptoms in those infected with influenza. It is unlikely that they would substantially modify the course or effectively contain the spread of a flu pandemic.

A number of antiviral medications (antivirals) are approved by the US Food and Drug Administration (FDA) to treat and sometimes prevent flu. At this time, Tamiflu and Relenza are the most likely antivirals to be used in a pandemic. There are efforts to find new drugs and to increase the supply of antivirals. If everyone follows the recommended uses of antivirals there will be more available for those who need them most.

How would pandemic flu affect communities and businesses?

If a severe influenza pandemic occurs, many people could become sick at the same time and would be unable to go to work. Many would stay at home to care for sick family members. Schools and businesses might close to try to prevent disease spread. Large group gatherings might be canceled. Public transportation might be scarce. These are examples of challenges that local communities, schools, civic organizations, and businesses have to work on together to plan for a pandemic response.

Could terrorists spread the avian influenza virus to cause a worldwide pandemic?

Experts believe it highly unlikely that a pandemic influenza virus could be created by terrorists. Developing a pandemic influenza virus would require extraordinary scientific skill as well as sophisticated scientific equipment and other resources.