Medical sleuths have been trailing the elusive cold and flu viruses for more
than a century. Now they finally might be onto something. A universal flu
vaccine could be on the horizon -- and even more effective treatments for the
common cold. Wayne Marasco, MD, PhD, is one of the most ardent sleuths. His
perp -- the flu virus -- has caused the deaths of more than 36,000 Americans,
and that’s just in one year.
Marasco is an associate professor of medicine at the Dana-Farber Cancer
Institute and Harvard Medical School. His work means that a universal flu
vaccine could be within reach -- one that would protect against all flu strains
over a lifetime, just like existing vaccinations for diseases like measles and
smallpox. Up to now, a universal flu vaccine has been elusive, because the
virus's constant ability to change has made it a hard target to combat. "The
virus undergoes a process we call antigenic drift, which means that it
continuously evolves so that it escapes the immune system," he explains. "We've
been kind of chasing our tails and immunizing every season to keep up with
The MMR vaccine is a combination vaccine to protect against measles, mumps, and rubella (German measles). Many children growing up in the U.S. are immunized as infants and toddlers, but childhood immunizations don't guarantee lifetime protection. Not all adults were immunized as children, many adults move to the U.S. from countries without immunization programs, and global travel makes transmission of infectious diseases a real risk.
As a general rule, adults born before 1957 are considered immune...
Even though only two different types of flu virus -- A and B -- are
responsible for most human flu cases, each type has several subtypes, and the
virus can change from season to season. That's why researchers can never seem
to keep up.
The 1918 Flu Pandemic
Compounding the problem is that people are always on the move. Hundreds of
years ago, Europeans first carried the flu to North America on ships, infecting
Native Americans who had previously been flu-free. Today, air travel can speed
flu viruses (including the H1N1, or swine, flu) around the world even faster.
Last year swine flu was reported for the very first time among the Matsigenka
tribe deep in the Amazon jungle, proving that no place is too remote to escape
a flu bug.
Even before the age of commercial air travel, the flu virus was able to get
around. In 1918, after the influenza A virus jumped from birds to humans,
soldiers in World War I spread the disease as they moved around the European
front. By the time the worldwide pandemic had ended a year later, a quarter of
Americans had become sick and 50 million people worldwide had died from the
illness, which was named the Spanish flu.
Researchers have since discovered one reason the 1918 flu strain was so
lethal. Unlike most of today's flu viruses, which can only copy themselves in
the upper respiratory system (mouth, nose, and throat), the Spanish flu was
able to replicate inside the lungs. As infected peoples' lungs filled with
fluid, they suffocated to death, sometimes within a day or two of showing
symptoms. While the H1N1 swine flu virus is also able to directly infect the
lungs, researchers note that so far it has not been nearly as deadly as the
Recently, researchers have discovered something else about that 1918 strain
-- it's the genetic granddaddy of the H1N1 flu strain that's making headlines
today. They traced the 2009 H1N1 virus back to the 1918 Cedar Rapids Swine Show
in Iowa, where many pigs developed a respiratory infection that looked an awful
lot like the influenza virus that was spreading like wildfire among humans.
Over the next 90 years, that virus swapped genes a few times with other flu
viruses, and re-emerged as the H1N1 flu strain we're dealing with today. The
H1N1 flu strain circulating now is nowhere near as lethal as its
predecessor, but unlike the H1N1 flu, it tends to be more dangerous to young
people, and researchers think they've figured out why. Older people
(particularly those born before 1950) have been exposed to the swine flu's
relatives, and their bodies have built up antibodies to the virus. Young people
don't have that same immunity.