MARY REICHARD, HOST: Coming up next on The World and Everything in It: the flu pandemic of 1918, part two.
One hundred years ago this fall, the influenza virus swept across the world, killing millions of people. As Susan Olasky reported last week, scientists now know a lot more about what caused the outbreak than they used to.
NICK EICHER, HOST: That’s because over the past three decades, researchers have unearthed frozen bodies of some who died during the 1918 pandemic. They’ve extracted DNA and coaxed secrets from it.
But they still don’t know enough—and many worry that another pandemic could arise.
WORLD Radio’s Susan Olasky brings us this story.
AUDIO: The growing flu danger, the CDC warning of widespread flu activity in 23 states. Doctors say we may now be approaching the peak of flu season.
SUSAN OLASKY, SPECIAL CORRESPONDENT: News reports like that one are common during the winter months. But some years the warnings have particular urgency. Doctors and researchers are always looking for signs of another pandemic flu.
Jen Shuford is an infectious disease physician in Austin, Texas. She’s currently the Infectious Disease Medical Officer for the state of Texas—so keeping track of each year’s flu is part of her job.
AUDIO: What we know about influenza viruses is that they mutate constantly… And so what we see typically is just these small mutations that occur and change the virus enough that year to year we have seasonal influenza or influenza epidemics that just happen in the U.S. during the winter months.
The problem is when whole gene segments swap with flu genes from another species.
AUDIO: So an influenza from a bird or a pig swaps genes with an influenza virus from a human. It causes large changes in that influenza virus to the point that there is no preexisting immunity in the human population. When we see those huge changes in the influenza genetic code that’s when we see pandemics. And so we saw that in 1918 and 1919. We saw it again in 1957 and in 1968. And most recently in 2009.
Usually flu mortality rates are highest among the very young and the very old—those in frail health. But the 1918 flu also affected those in the prime of life—people in their 20s and 30s.
AUDIO: We haven’t seen that pattern before or since. It’s uncertain why that is.
There was the war, of course. But 20- to 40-year-olds who stayed home also had high mortality rates.
AUDIO: It appears that that virus was very, very virulent. It did cause severe disease. But when testing the people who actually died of influenza, many of them appeared to have a bacterial pneumonia in the same pattern that we see today.
Doctors today have a huge advantage over doctors a century ago. They’re able to monitor the virus as it circulates during the cold months in both the Northern and Southern hemispheres. They try to guess what mutations might occur over the next several months.
AUDIO: They then make an educated guess on what the vaccine components should be for the next season based on the circulating viruses from the previous season as well as the genetic changes that are occurring right now.
They check the virus against the one they’ve been using to make the vaccine. Is it still a good match, or do they need to change the components of it?
AUDIO: And so this is just a constant procedure that they do to try to fine tune our vaccine components year to year.
Scientists monitor animal viruses they know can jump to humans. They have stores of so-called candidate viruses in case they need to manufacture a vaccine quickly.
AUDIO: However, there are lots of other types that we haven’t made those preparations for. And so thankfully there’s organizations around the world that are keeping a close eye on these circulating viruses and genetically characterizing them, so that we can see what’s happening with their genetic code and if it represents a threat to us.
One interesting thing about the 1918 flu: People older than age 60 didn’t die at the expected high rate. Researchers believe they may have had earlier exposure to one of the virus strains that was circulating.
AUDIO: Our body does kind of accumulate an immunity to viral types that we’re exposed to through our lifetime. So the older you are, the more influenza viruses that your body has seen circulating.
And no, you can’t catch influenza from the flu shot–though some people get the flu even after having the shot.
AUDIO: And it’s maddening, I agree. However, what we know with flu vaccines is that it in many cases it does prevent infection with the flu. In the cases that it doesn’t prevent the infection it often decreases the severity of illness that they experience and can decrease hospitalizations and deaths.
Scientists still hope for a scientific breakthrough—perhaps a universal vaccine.
AUDIO: A lot of scientists are working on this, and… we’re hoping that we get to the place where we can have a universal vaccine, and not having to worry about changing our seasonal flu vaccine every year or preparing pandemic vaccines in advance, but instead, something that will work against all flu viruses for the entire population.
In the meantime, let’s pray that we never again encounter pandemic influenza of the sort that our grandparents and great-grandparents faced.
For WORLD Radio, I’m Susan Olasky reporting from Austin, Texas.