Epidemiology & Disease Prevention - Cerro Gordo County Department of Public Health

Disease Prevention

Pandemic Flu: Frequently Asked Questions FAQ Key

Vaccine & Anti-virals

What drugs are available for treatment of seasonal and avian influenza?
Two drugs (in the neuraminidase inhibitors class), oseltamivir (commercially known as Tamiflu®) and zanamivir (commercially known as Relenza®) can reduce the severity and duration of illness caused by seasonal influenza. The effectiveness of the drugs, among other things, depends on their early administration (within 48 hours after symptom onset). For cases of human infection with H5N1, the drugs may improve prospects of survival, if administered early, but clinical data is limited. The H5N1 virus is expected to be susceptible to the neuraminidase inhibitors.

For the neuraminidase inhibitors, the main constraints - which are substantial - involve limited production capacity and a price that is prohibitively high for many countries. At present manufacturing capacity, which has recently quadrupled, it will take a decade to produce enough oseltamivir to treat 20% of the world's population. The manufacturing process for oseltamivir is complex and time-consuming, and is not easily transferred to other facilities.

So far, most fatal cases of H5N1 infection have resulted from the effects of the virus, and cannot be treated with antibiotics. Nonetheless, since influenza is often complicated by secondary bacterial infection of the lungs, antibiotics could be life saving in the case of late-onset pneumonia.

How would antivirals be used?
Antivirals may 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 an influenza pandemic.

A number of antiviral medications (antivirals) are approved by the U.S. 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 it most.

What is the difference between a vaccine and an antiviral?
Vaccines are usually given as a preventive measure. Currently available viral vaccines are usually made from either killed virus or weakened versions of the live virus or pieces of the virus that stimulate an immune response to the virus. When immunized, the body is then poised to fight or prevent infection more effectively.

Antivirals are drugs that may be given to help prevent viral infections or to treat people who have been infected by a virus. When given to treat people who have been infected, antiviral medications may help limit the impact of some symptoms and reduce the potential for serious complications, especially for people who are in high-risk groups.

Does the current seasonal influenza vaccine protect me from avian influenza?
No. Seasonal influenza vaccine does not provide protection against avian influenza.
How many influenza vaccine manufacturers have production facilities in the United States?
Currently, Sanofi Pasteur and MedImmune have influenza vaccine production facilities in the United States, although only Sanofi Pasteur's entire production process is based in this country.

The U.S. Department of Health and Human Services (HHS) has made the establishment and expansion of U.S.-based manufacturing facilities for influenza vaccine a key component of its strategy to improve the security of the influenza vaccine supply.

How much time does it take to develop and produce an influenza vaccine?
The influenza vaccine production process is long and complicated. Traditional influenza vaccine production for the U.S. 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 vaccine. Researchers are making and testing possible H5N1 vaccines now.

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.