Public health officials say the outbreaks of measles and whooping cough over the past year put a spotlight on the need to ensure as many children as possible get their immunizations. That effort is getting help from an unlikely source: a state welfare agency that will reduce cash aid if parents fail to keep their kids' vaccinations up to date.

Sara Martín is a case in point. After reading a bedtime story to her children Tzintia, 4, and Ricky, 20 months, the 29-year-old single mother recalls a more stressful time in life, when she had trouble keeping on top of simple things like taking the kids to the dentist and making sure they were up to date on their shots.

"When they became toddlers, I started to fall a little behind on the vaccinations," says Martín, who lives in South Los Angeles. "Not intentionally, that’s just kind of how it happened for me."

That got her into trouble with CalWORKs, the state’s welfare program that provides cash aid to low-income families. Martín says she was already struggling to get by when the agency reduced her aid for not submitting the immunization records for her daughter.

"So I was working with an income of $200 a month," she recalls. "It was very, very, very difficult to manage."

Families on CalWORKs risk losing a part of their cash aid if they don’t submit up-to-date immunization records or an exemption form for children under six. Exemptions are granted for medical reasons or personal beliefs. Clients can also file for an exemption based on a lack of transportation or having a physical disability.

CalWORKs will restore benefits once parents submit paperwork showing their kids are up-to-date with their shots.

That’s what happened with Sara Martín, but she says it wasn't easy.

"I don't have a car; I would use public transportation with the kids and so that made it really difficult to go back and get the vaccinations so that I [could] re-establish my aid," she says, recalling how she had to take the kids on two different buses to get to a downtown L.A. clinic.

By the time CalWORKs restored her funding, Martín says she had gone about a month without her full cash benefits.

CalWORKs, which is administered by each county, may be one of the only agencies with the ability to enforce compliance with vaccination laws.

Former State Senator Denise Moreno Ducheny led the effort to create CalWORKs in 1997. CalWORKs, which stands for California Work Opportunity and Responsibility to Kids Act, has multiple eligibility and work requirements.

"It's a contract," Moreno Ducheny says. "It's a way to say here’s your piece of the deal and here's our piece of the deal."

The vaccination requirement has been part of the program from the beginning, she says. Under CalWORKs rules, families are given about a month to submit their forms before they face penalties. Families are asked for the information when they apply and each year during recertification for the program.

"It's meant to be a way of bringing it to your attention," Moreno Ducheny said. Families say, "'Oh shoot, I lost the money, I better go,'" she says. "That is what that is meant to do, it’s not meant to penalize them forever."

The vaccination requirement is intended to make sure a child is healthy and ready for childcare or school so that parents can go to work, which is CalWORKs' ultimate goal, Moreno Ducheny notes.

The aid that is cut is the portion that is intended for the parent or parents, which ranges from about $120 to $140 a month, depending on the county.

In Los Angeles County, there are roughly 6,000 families that have not submitted their vaccination records. That represents about 2 to 4 percent of CalWORKs households in the county with kids under six, says Silvia Valencia, who oversees the program for the county.

"Every dollar the family gets through the CalWORKs program helps them pay for shelter and other essentials, so a penalty really takes a hit on the family," Valencia says. "For the most part" families try to get the penalty reversed "as soon as possible," she adds.

Officials said not all of the cases "in penalty" see their aid reduced. CalWORKs will not reduce benefits to a household if only the children are on the program.

In those cases, social workers try persuasion, says Ben Blank, deputy director of family self-sufficiency for Orange County Social Services.

"We...try to motivate the family to get the vaccinations and inform them of the health risks involved if their children are not immunized," he says.

Welfare advocacy groups have not raised any objections to CalWORKs' approach to the vaccination issue. California is one of two dozen states that cut welfare benefits to families that fail to submit immunization records, according to Caroline Danielson, a senior fellow at the Public Policy Institute of California.

State Assemblywoman Patty López (D-San Fernando) considers the CalWORKs documentation requirement burdensome, and she says she is trying to ease that burden with AB376. The bill would require the county to first check the statewide California Immunization Registry for a child’s vaccination record before requiring a parent to produce proof of compliance.

"I have a lot of neighbors and families and friends that are in the system, and they have really hard situations with their kids," says López. "It's really easy for the social worker just to go online and to look for those records."

The registry is run by the California Department of Public Health and it is meant to be a go-to secure database for immunization records. But participation in the registry by health care providers is voluntary and it is hardly an exhaustive resource for all of California’s children.

"Based on population, approximately 55 percent of children age 0-5 years and 66 percent age 6-18 years have two or more vaccine doses recorded" in the registry, notes Chavez.

In interviews at playgrounds and apartment complexes near downtown L.A., several mothers on CalWORKs all say they get their kids vaccinated on schedule for health reasons. Submitting the records, they add, is just part of the deal.

Marcela Zuniga, 25, takes a break from cleaning her apartment at the Ramona Gardens public housing complex in Boyle Heights to talk, while her three kids, ages 3, 5 and 7, chase friends around the courtyard.

"It's really important for me to have them updated with all of that," she says. "So that's why I do it, to keep them healthy."

Zuniga says she submits her forms to CalWORKs regularly, noting, "if you don't do it they will take away the CalWORKs from you."

Families on CalWORKs can lose benefits for other reasons as well, points out Orange County's Blank.

"The immunization eligibility factor is one of dozens and dozens of eligibility factors, like an income amount or liquid resources, available time on aid, citizenship, residency requirements, things of that nature," he says.

Across the region, county officials report around 92-98 percent of CalWORKs families with kids under six filed paperwork in February showing either they vaccinated their kids or didn't based on a legal exemption.

Los Angeles County: 96-98 percent of cases with kids under six are in compliance

San Bernardino County: 92 percent of cases with kids under six are in compliance

Ventura County: 97 percent of cases with kids under six are in compliance

Orange County: 98 percent of cases with kids under six are in compliance

Riverside County: did not provide total number of cases required to be in compliance

Officials could not break the numbers down further to show how many kids are vaccinated, how many have opted out due to medical or personal beliefs and how many have good cause exemptions. The state does not require reporting of this data, officials note.

Los Angeles County says it will provide the data, but it will take six weeks. Other counties say it is impossible to do without looking at each case file because the vaccination forms are scanned and kept separately rather than aggregated into a comprehensive database. Orange County says it could work on trying to pull the data if another county agency asked for it.

Former lawmaker Moreno Ducheny says required reporting of such statistics was not part of the original reform discussion, but says it could be beneficial now in light of the recent measles outbreak. A report would show how many children are vaccinated and how many are not based on medical and personal belief exemptions or on a "good cause" exemption granted by the agency. A "good cause" exemption gives parents more time - up to an additional year - for reasons such as not having transportation or being disabled.

One of those outs may be going away soon. The personal belief exemption faces extinction across the state if a pending bill becomes law.

Senate Bill 277, co-authored by pediatrician Richard Pan (D-Sacramento) and Bill Allen (D-Santa Monica), seeks to repeal the controversial personal belief exemption, which allows parents to choose not to vaccinate their children for school or other state programs that require it.

The Senate Health Committee approved Pan and Allen’s bill last week.

Sara Martín, who lost part of her cash benefit and had to scramble to get it back, says she does not think CalWORKs should have cut her benefits for falling behind on her daughter’s vaccinations.

But she says she believes immunizing her children is important.

Today, she says her kids are up-to-date on their shots, she has a full-time job and she’s no longer on CalWORKs.

The story was updated on April 14, 2015 to correct the city that Assemblywoman Patty Lopez represents and to add Orange County's rate of compliance.