Last year, dying children stood outside hospitals in northern India waiting for an empty bed during one of the worst encephalitis outbreaks in recent memory. Now, they're lining up again for hours to receive a shot that could save their lives.

Since May, nearly 11 million children ages 1 to 15 have been vaccinated against mosquito-borne Japanese encephalitis in high-risk areas of four northern Indian states, U.S.-based nonprofit group PATH said Tuesday.

It was the first-ever mass immunization campaign to fight the brain-damaging virus, and many skeptics doubted it would ever happen this fast.

But the 2005 outbreak, which killed about 1,800 children and left many survivors permanently disabled with physical and neurological damage, sparked a wave of quick action rarely seen within India's bureaucracy-clogged government.

Critical news reports and images of unconscious children lying two to a bed led to a public outcry, and India's top health officials promised to take action before the next rainy season, said Dr. Julie Jacobson, director of PATH's Japanese Encephalitis Project.

"They latched on to the idea of vaccine being the answer," said Jacobson, who pushed for six years for the vaccination campaign. "All the rest of the stuff doesn't work. They've been [having outbreaks] for 30 years, and it keeps happening."

Most victims live in the poorest corners of India, typically surrounded by rice paddies in farming villages. The mosquitoes transmit the virus from pigs and birds to humans. Since most infected people never develop symptoms, many adults are immune from earlier exposure — leaving young children most vulnerable.

Japanese encephalitis is closely related to West Nile virus but is found only in Asia. It attacks the central nervous system, damaging the brain and spinal cord. High fevers are often followed by seizures and comas, and many children need ventilators to breathe.

An estimated 50,000 cases — more than 10,000 of them fatal — occur annually, the World Health Organization says. Up to a third of survivors suffer problems ranging from paralysis to mental disabilities.

India's vaccination campaign was based on a partnership with China.

The Chinese have virtually wiped out the disease after making their own vaccine and distributing it widely since 1988. It is made from a weakened form of the virus and given in one shot that protects for a lifetime.

India produces limited amounts of another vaccine, used widely in Western countries. It is more expensive, harder to manufacture and requires multiple injections. Even at full capacity, the sole Indian manufacturer could only reach a fraction of children in need.

China agreed to make about 13 million doses for India at a discounted price — about $3.8 million, said Dr. S. Sarkar, an adviser on immunization for WHO and the Indian government. That's about 29 cents per child.

Sarkar ran the country's immunization program for 18 years and saw the virus return each year after the monsoon season from June through September left ideal breeding grounds for mosquitoes. He was amazed by the huge crowds of children that showed up for the free shots, which will later be given to other affected areas and eventually added into routine vaccinations.

"Without any fear in their eyes, they were coming out of the centers laughing. They didn't cry when they were standing and getting their shots," Sarkar said. "I think we have achieved something."

Jacobson said the campaign should produce a dramatic decrease in cases this year, but some doctors fear the campaign — covering 11 districts in the states of Uttar Pradesh, West Bengal, Assam and Karnataka — will still not be enough. Most children did not fall ill last year until late in the rainy season.

Health officials in Assam last week reported 25 Japanese encephalitis deaths and dozens of other suspected cases.

In Uttar Pradesh state, four children have already tested positive for the virus and another 48 have been hospitalized with symptoms, said Dr. A.K. Rathi, pediatrics chief at BRD Medical College hospital in Gorakhpur, where the bulk of last year's cases died.

About 200,000 unprotected children remain scattered across hundreds of villages, said Dr. K.P. Kushwaha, a senior pediatrician at the hospital.

"The [encephalitis] patients have started trickling in," he said. "It is a matter of time when they will start pouring."