As scientists struggle to understand the threat posed by Zika virus, there's another viral infection that's a known danger in pregnancy and that harms 100,000 babies a year, even though it has been preventable with a vaccine since 1969.
The disease is rubella, or German measles. Like Zika, the rubella virus often causes either a mild rash or no symptoms at all.
When women get rubella while pregnant, however, there can be devastating consequences for the fetus, including deafness, heart defects and even microcephaly — the brain abnormality that's raised such alarm about Zika.
Worldwide, about 300 infants a day are born with damage from rubella, according to Dr. Susan Reef, with the Centers for Disease Control and Prevention's global immunization division, who notes that a dose of rubella vaccine can be purchased for about 50 cents.
"But in some countries, that's a big financial burden," Reef says, rattling off a list of nations that don't yet vaccinate, including India, Indonesia, Nigeria, Afghanistan and Pakistan.
About half of all children born worldwide have no access to rubella vaccine, she says. But more countries are starting to vaccinate, thanks to a recent push by the World Health Organization and increased funding from the GAVI Vaccine Alliance.
"It's a slow, gradual increase," Reef says.
The United States had a huge rubella outbreak in the 1960s, and in 1965 the disease made the cover of Life magazine, which warned that the virus would harm up to 20,000 babies in the U.S.
That's surely an underestimate, says Dr. Stanley Plotkin, now a professor emeritus of microbiology at the University of Pennsylvania, who had one of the few labs back then that could diagnose the disease.
"I calculated that 1 percent — one out of a hundred pregnancies in Philadelphia — were affected by rubella," says Plotkin. "I was constantly seeing women who wanted to know if they had been infected, and speaking with obstetricians who were either doing therapeutic abortions or delivering babies with congenital rubella."
As researchers try to figure out how much risk Zika virus poses to a fetus, Plotkin says it's deja vu for folks who lived through that extensive rubella outbreak.
"It enabled the virologists, among them myself, to describe in detail what the virus was doing and to show beyond any doubt that the virus was infecting the fetus and causing the abnormalities," says Plotkin.
The outbreak also forced major social changes, says Dr. Louis Cooper, a pediatrician and researcher who is now a professor emeritus of pediatrics with Columbia University. Back then, his small lab in New York was overwhelmed with women seeking tests and information.
"Before Roe v. Wade, because of the rubella outbreak, we were able to pass much more liberalized right-to-abortion [laws] in New York state," says Cooper, who adds that rubella also pushed the federal government to create new programs for special education.
Cooper became very close to families affected by rubella and feels deeply for women who now face Zika. "At the moment we have no way to stop the infection," he says, "and it doesn't look as if we have any way to reduce the risk to the developing babies." The size of that risk, he notes, remains to be quantified.
In some countries, like the United States, vaccination against the rubella virus was adopted quickly. And last year, public health officials said rubella had been eliminated from the Americas.
Still, seeing Zika in the headlines is a potent reminder of how scary rubella was for pregnant women. "It brings flashbacks of what rubella was like prior to the pre-vaccine era," says Reef.
Asked if Zika, like rubella, is likely to continue to harm infants even decades after a vaccine is developed, Reef says: "That's a great question, and I really don't know what's going to happen. Maybe that's a possibility."
AUDIE CORNISH, HOST:
The Zika virus is making headlines because of its potential links to birth defects. Half a century ago, the big scare was rubella. And NPR's Nell Greenfieldboyce reports the danger is still there, with around 300 infants born with damage from rubella every day.
NELL GREENFIELDBOYCE, BYLINE: Rubella, or German measles, made the cover of Life magazine in 1965. Back then, the magazine warned that the outbreak would harm up to 20,000 babies in the United States. Stanley Plotkin says that's surely an underestimate.
STANLEY PLOTKIN: I calculated that 1 percent - 1 out of 100 pregnancies in Philadelphia - were affected by rubella.
GREENFIELDBOYCE: Philadelphia was where Plotkin was working at the time, trying to develop a vaccine for rubella. In the 1960s, his lab was one of the few that could diagnose this illness which typically causes just a mild rash or no symptoms at all, just like Zika.
PLOTKIN: I was constantly seeing women who wanted to know if they had been infected, speaking with obstetricians who were either doing therapeutic abortions or delivering babies with congenital rubella.
GREENFIELDBOYCE: Congenital rubella causes problems like deafness, heart defects, and microcephaly. That's the brain abnormality that's caused such alarm with Zika. Right now, researchers are trying to figure out how much risk Zika virus poses to a fetus. And Plotkin says it's deja vu for folks who lived through the massive rubella outbreak decades ago.
PLOTKIN: It enabled the virologists - among them, myself - to describe in detail what the virus was doing and to show beyond any doubt that the virus was infecting the fetus and causing the abnormalities.
GREENFIELDBOYCE: Another physician-researcher named Louie Cooper had a small lab in New York that was overwhelmed with women seeking tests and information. Cooper says the outbreak forced social changes, like easier access to abortion.
LOUIE COOPER: Before Roe v. Wade, because of the rubella outbreak, we were able to pass much more liberalized right to abortion in New York State.
GREENFIELDBOYCE: He says rubella also pushed the federal government to create new programs for special education. He became very close to families affected by rubella and feels deeply for women who now face Zika.
COOPER: At the moment, we have no way to stop the infection, and it doesn't look as if we have any way to reduce the risk to the developing babies. How much that risk is, that hasn't been quantitated yet.
GREENFIELDBOYCE: For rubella, the big change was the vaccine. The first vaccine became available in 1969. And last year, public health officials said rubella had been completely eliminated from the Americas. But elsewhere, it's still a real threat. More than half of the babies in the world do not have access to rubella vaccine. Susan Reef is with the Centers for Disease Control and Prevention.
SUSAN REEF: There's about a hundred thousand infants born each year with CRS.
GREENFIELDBOYCE: So you're telling me that every year now, there's a hundred thousands babies in the world born with congenital rubella syndrome.
REEF: Yes, that's what we estimate - yes.
GREENFIELDBOYCE: And this is for a disease where we had an effective vaccine in 1969.
REEF: That's correct.
GREENFIELDBOYCE: She says the vaccine costs about 50 cents, but a lot of countries haven't pursued rubella vaccination.
REEF: Countries like India, Indonesia, Nigeria, Afghanistan, Pakistan.
GREENFIELDBOYCE: She says some countries have started to introduce this vaccine, and progress is being made. But it's happening slowly. Nell Greenfieldboyce, NPR News. Transcript provided by NPR, Copyright NPR.