Americans’ strong aversion to late-term abortions drops precipitously if a developing fetus would likely be born with severe damage from the Zika virus, a new STAT-Harvard poll found.

It showed that 59 percent of respondents thought women should have the right to end a pregnancy after 24 weeks of gestation if testing showed there was a serious possibility the fetus had microcephaly caused by the mother’s Zika infection.

Microcephaly is a condition in which a baby is born with an abnormally small head and often an underdeveloped brain, and it is typically diagnosed after the 24th week of pregnancy.

But most states have laws that restrict abortions either after a certain point in pregnancy — 22 set the cutoff by the 24th week — or when the fetus is viable outside the womb (also about the 24th week), according to the Guttmacher Institute.

The poll also found that a majority of Americans are unaware that Congress left for the summer recess last month without approving new funding for the nation’s Zika response. Among those who knew the legislation had not passed, twice as many blamed Republicans for the impasse than Democrats. These numbers provide political context for President Obama’s remarks at a press conference Thursday calling on Congress to “do its job” and approve the spending.

When asked which of the presidential candidates would do a better job handling the Zika outbreak, Democrat Hillary Clinton got the nod, with 41 percent. Republican nominee Donald Trump was named most capable of handling the outbreak by 30 percent. Fifteen percent chose neither, and 10 percent were undecided.

The issue of whether to permit late-term abortions in cases of Zika-related birth defects is becoming more pressing as Zika infections among pregnant women in the United States continue to mount. As of Thursday, the Centers for Disease Control and Prevention said 479 women have been infected while pregnant. Of those, 15 have given birth to a baby with Zika-related birth defects and 6 pregnancies have been lost to miscarriage, stillbirth, or abortion.

Generally, the vast majority of Americans oppose late-term abortions. In a separate poll conducted a week earlier by STAT and Harvard, only 23 percent said they favored allowing a woman to obtain an abortion after 24 weeks — when the question did not raise the possibility of microcephaly.

Among Democrats, support for late-term abortion increased from 34 percent to 72 percent when there was a strong likelihood of Zika-induced severe birth defects, the STAT-Harvard T.H. Chan School of Public Health poll found.

But even among respondents who identified themselves as Republicans, support for abortion after 24 weeks was surprisingly high, with 48 percent saying it should be allowed if Zika-induced birth defects were likely — compared with just 12 percent who felt that way about late-term abortion in general.

Read full STAT-Harvard poll results here

Linda Krause is one of those polled who feels that Zika’s severe birth defects constitute a special case.

Krause, of Fredonia, Kan., normally disapproves of abortion after three months. But Zika is an exception. “That’s a life-threatening illness for the mother and the baby,” she told STAT in a follow-up interview.

Vivian, a Republican from Atlanta, said she favors late-term abortions in the Zika context — even though her own son was born premature at 24 weeks and two days — almost 16 weeks early. Now a healthy 20-year old, he spent months in a neonatal intensive care unit.

Told during her pregnancy that her son would have Down syndrome, Vivian, who asked that she be identified by her first name only, chose not to terminate. But she said the choice should be up to individual women.

“It’s personal for everybody. I can’t speak for someone else going through a different situation if I haven’t been there,” she said.

The degree of support for late-term abortions in the context of Zika was notable, said Gillian SteelFisher, deputy director of the Harvard Opinion Research program.

“The data are clear that although people aren’t in favor of late-term abortion in general they are sympathetic to women when their pregnancies can be affected by Zika virus,” she said.

Dr. Warren Hern, who performs abortions — including late abortions — in Boulder, Colo., said “it’s not reasonable or logical” to allow an exception when a fetus has been damaged by Zika, but not in cases where other serious birth defects are identified.

“There are many, many reasons why women seek late abortion. And many of those reasons have to do with catastrophic fetal abnormalities that are not discovered until late in pregnancy,” Hern said in an interview.

Infection during the first trimester of pregnancy can trigger devastating damage in developing fetal brains. But infections in the second trimester can also lead to brain damage, said Dr. Karin Nielsen-Saines, a professor of pediatric infectious diseases at the David Geffen School of Medicine at the University of California, Los Angeles. Nielsen-Saines is involved in a study in Brazil where researchers are following women who have been infected in pregnancy.

“Even after the brain is formed, there are some problems that happen,” she said.

“There’s atrophy, there’s damage, even later in pregnancy. So just because someone’s reached the second trimester, it doesn’t mean that there couldn’t be a problem if they were to contract Zika.’’

That type of damage can take several weeks to become apparent in prenatal testing. By the time some women learn what Zika has done to the fetuses they are carrying, their access to legal abortion could be blocked in most states.

The telephone poll of 1,016 adults was conducted July 20 to 24, during the week when Florida announced it had discovered two people who had possibly contracted Zika locally, most likely through the bite of an infected mosquito.

Since then, the number of cases in the Florida outbreak — believed to be centered in a one-square mile area just north of downtown Miami — has swelled to 15.

The poll — which had a margin of error of plus or minus 3.6 percentage points — also found that only 44 percent of Americans realized the Zika funding stalemate has not yet been resolved. Lawmakers left Washington last month after Senate Democrats wouldn’t back a deal negotiated by House and Senate Republicans that included provisions affecting Planned Parenthood and the Affordable Care Act.

Of people who were aware that Congress has not yet provided Zika funding, 55 percent said not passing the legislation is a problem. More blamed the Republicans than the Democrats for the continued impasse — 42 percent said it was the Republicans’ fault, compared with 22 percent who faulted the Democrats. Seventeen percent said both parties are equally to blame. The apportionment of blame generally followed party lines.

About one-fourth of those polled said funding Zika response efforts should be a top priority for the federal budget, nearly half said it was important but not a top priority, and 20 percent said it was not that important.

The poll also showed that in the third week of July, barely half of Americans — 52 percent — felt Zika posed a public health threat in this country. And only 22 percent felt that it was a major threat.

But it is not known whether the growing outbreak in Florida has changed opinions on that question.

“We’ll see what happens post-Florida and over time,” SteelFisher said. “But this is where we’re starting from and it is mid-mosquito season in much of the United States.”