As the 2011 flu season gets underway, it is reported that the vaccines given for this dreaded disease may be far less effective than thought, according to a new study. Michael Osterholm, an infectious disease specialist at the University of Minnesota, found that the most common flu vaccine is effective for just 59 percent of healthy adults, well below the 70 percent to 90 percent level that is generally quoted. “We’re stuck with a vaccine that has been around for 60 years and not changed much,” Osterholm said. He stressed the need for an all-new generation of flu shots, especially in case there is a future pandemic.
“Today’s flu shot is like an iPhone 1.0,” according to Osterholm. “What we need is an iPhone 10.0.” Scientists are presently working on a “universal flu shot” that would be effective for years. Francis Collins, director of the National Institutes of Health (NIH), said that such a vaccine could be developed within the next five years.
Health officials recommend that all Americans over six months of age get a flu shot. Nearly 131 million people – just 43 percent of the population — received the flu vaccine in 2010, according to the Centers for Disease Control and Prevention (CDC).
Although Osterholm does not dispute the need for the current vaccines, he said the common perception that they are “good enough” obstructs the development of improved therapies. In a study published in The Lancet Infectious Diseases, Osterholm and his colleagues examined 5,707 vaccine studies published over the last 40 years. They focused 31 studies that tested for the presence of flu in laboratory tests rather than counting an increase in flu antibodies — a speedier method that researchers say overestimates the vaccine’s effectiveness. Additionally, they concentrated on results to those that used randomized controlled trials or other observational methods that did not have “selection bias,” which could lead to sicker people being excluded from the study.
“We found a number of differences in how influenza vaccine has performed in different populations of people,” Osterholm said. Because 3,000 to 49,000 Americans die of flu every year – the number varies because the disease is not easily predictable, seasonal and pandemic – its severity differs. In other words, flu is a unique public health problem. Because of those variations, each year’s vaccine has some differences. “It’s clear that what we really need is to develop new and better vaccines,” according to Osterholm. The holy grail would be a vaccine that is effective against all varieties of flu.
The H1N1 vaccine performs slightly better than seasonal flu shots, preventing infection in 69% of adults under 65. Nasal sprays do even better, preventing infections in 83 percent of children aged seven or less, according to The Lancet. One study found that flu shots reduce hospitalizations by eight percent. That is significant, however, because the flu sends about 200,000 Americans to the hospital every year. The results should not deter people from getting vaccinated, Osterholm said. “We have an obligation to tell the public what we know. We know we need better vaccines. But 59 percent protection is still better than zero. To me, that still very much recommends getting vaccinated.”
“There isn’t any doubt that influenza vaccine is a pretty good vaccine, but it’s not an excellent vaccine, like polio or measles,” says William Schaffner, a professor at Vanderbilt University School of Medicine. “Even in the best of times, it’s not capable of completely eliminating infections.”
By comparison, just two measles vaccines prevent about 95 percent of infections, and polio vaccines have eliminated polio in most countries.
The bottom line, is that most years, it will prevent illness, it will prevent hospitalizations, and it will prevent deaths.” But, he added, “it won’t prevent them all and it cannot eradicate influenza,” as vaccines have done for certain other diseases such as polio and measles.
The American examination could help public health planners determine how to get the most our of the vaccine while better vaccines are developed, said Dr. Scott Halperin, director of the Canadian Centre for Vaccinology in Halifax. “A lot of research is going on in the flu vaccine field to get a better vaccine,” Halperin said. “But having said that, you know 59 or 60 percent is still far better than zero percent.”
Andrew Pavia, M.D., who chairs the Pandemic Influenza Task Force of the Infectious Diseases Society of America, said the study confirms what is already understood about the current flu vaccine. “Everyone agrees that we need better vaccines and we are making progress in that direction. We have known for years that the vaccine we have does not provide a first-rate level of protection in the elderly and the very young, but it does provide protection. It would be terrible if the message to the public was that getting vaccinated isn’t important.” In fact, the less effective a vaccine is, the more important it is that as many people as possible are vaccinated so that those who are most vulnerable are protected. “With a vaccine that is less than perfect, which is most of our vaccines, much of the protection comes from having widespread coverage within a community,” Pavia concluded.