Influenza, known to most of us as simply “the flu,” is a collection of viruses that typically cause well-known symptoms such as fever, aches, pains, cough, and stomach upset. It can sometimes be complicated by more troubling problems such as pneumonia. Influenza is a serious cause of death each year in the U.S., mostly in young children, the elderly, and those with severe chronic diseases, especially those that depress the immune system.
With the imminent arrival of the flu season, questions and concerns regarding the flu vaccine are beginning to peak. Specifically, are people with MS at higher risk for the flu and should they receive the vaccine?
A SHORT COURSE IN VACCINES
Vaccines are developed against a variety of different disease-causing pathogens, including bacteria and viruses. There are at least three types of vaccines: whole virus/bacteria vaccines which are either inactivated (killed) or live but attenuated (weakened); and vaccines made with just parts of a virus or bacteria, typically part of the outer coat.
Most of the vaccines in common use for MS patients are the whole virus/bacteria type. Killed or inactivated virus vaccines are prepared by literally killing the pathogens (disease-producing agents) that make up the virus or bacteria. Although the virulent microorganisms are dead, they still possess the ability to provoke the immune system into producing antibodies and these protect the individual from the disease in question. Because the pathogens have been destroyed, killed vaccines do not, unlike live virus vaccines, have the potential to give the individual the disease produced by the pathogen virus or bacteria.
The other type of whole virus/bacteria vaccine uses “live” pathogens that are “attenuated”—or damaged—to make them made less virulent and harmful. This is often done by “passing” the strain multiple times, which means growing the virus repeatedly, selecting the strains that appear to cause less disease (perhaps in an animal model of the human disease), and thereby reducing its strength. Examples of live virus vaccines are the measles, mumps and rubella.
The typical Influenza A vaccines in common use in the last decade or longer have been available both as inactivated (flu shot) and live, attenuated (oral). In addition, for many years there has been available a live, attenuated vaccine, taken by mouth, which is also highly effective.
CAN FLU SHOTS CAUSE EXACERBATIONS?
Although there were some initial concerns that the flu vaccine might provoke MS exacerbations, research does not support this. A 1993 study, headed by Dr. Aaron Miller of the National MS Society, found that among the 104 study participants there was no difference in the number of exacerbations experienced by those who received the flu vaccine and those on placebo. Other studies and extensive data collection have been undertaken as well and these have consistently found no link between relapses and the flu vaccine.
SHOULD PEOPLE WITH MS GET FLU SHOTS?
The flu shot, which is produced and distributed each year in order to protect individuals from the seasonal flu, is an example of an inactivated (killed) virus vaccine. For people with MS, the flu vaccine has proven to be a helpful tool for staying flu-free.
For these reasons, MS specialty doctors and the Center for Disease Control and Prevention (CDC) encourage MS patients to get the flu vaccine.
The Rocky Mountain MS Center and the National MS Society do not recommend the live attenuated vaccine for those with MS, and instead suggest use of the inactivated flu shot vaccine.