"Her mother was so young and to lose a baby within one week at the age of 19, I cannot think of a worse thing to happen to someone than to lose a baby," she said.
In countries like Sierra Leone, still recovering from an 11-year civil war that ended in 2002, high death rates are due to a combination of deficient health services and education.
Most women have not been vaccinated because of insufficient resources or a lack of information about the preventive measure.
These factors -- together with a lack of transportation in rural areas to bring pregnant women to health clinics -- cause most women in Sierra Leone to give birth at home, in unsanitary conditions that are the breeding grounds for the bacteria that cause tetanus.
The bacteria are spread when dirt enters the body through a cut or wound. Mothers are often infected by contaminated instruments during childbirth. It similarly spreads to their infants when traditional birth attendants cut the umbilical cord with an unsanitary knife, or, as is often the case, the umbilical cord is dressed by the traditional method of packing it with dirt, clay or cow manure.
Once tetanus has been contracted, the most notable symptom is stiffness of the jaw, which leads to stiffness in the throat and difficulty in swallowing.
In babies, that makes feeding impossible because the infant loses the ability to suck. Soon after, the other muscles become stiff and the infant experiences muscle painful spasms and contractions. Death is virtually certain.
"It's heartbreaking," Hayek said of the situation. "As sad as it is, it makes it extra sad that there is so much that can be done and it's not done. At the same time there is a little bit of hope in knowing there is a lot you can do."
Hayek hopes her trip will show those who have participated in the campaign by purchasing Pampers that they are making a real difference on the ground in countries like Sierra Leone.
"I want all the people that bought the Pampers and were hoping that their contribution got to the right place and to the right people and wondered if this actually happened to know that I can testify that it did. And that I unfortunately was able to testify [to] what happens when it doesn't get here in time."
An estimated 386 million vaccines are needed to wipe out tetanus in the remaining 26 countries yet to eliminate the disease. Pampers expects to donate at least $10.8 million during the next three years and that will fund more than 200 million more tetanus vaccines, but the work has just begun.
"I think the needs are well identified by the government and by UNICEF ... definitely more facilities. ... There is a huge need for more doctors," Hayek said. "And then you have to understand there's no electricity. So these medications have to be put in cool places; you need to refrigerate them. So if you just get the medication, there might not be a place to store them. And if you get the refrigerator, there might not be electricity for them."