CHANGGANG, China— Few farmers in this southern Chinese village gave much thought to the swine flu epidemic that had begun spreading rapidly in the United States early this summer until police sealed its 100 residents off from the outside world for about a week. It turned out that a visitor from California had shown symptoms of the swine flu virus, or H1N1, when he arrived for a funeral.

Quarantines and medical detentions are among the aggressive measures that Chinese officials have taken to slow the transmission of H1N1, which quickly spread worldwide after being first diagnosed in North America.

To howls of protest from around the world, China isolated entire planeloads of people entering the country if anyone on the plane exhibited flu-like symptoms. Local authorities canceled school classes at the slightest hint of the disease and ordered students and teachers to stay home. China was virtually alone in taking such harsh measures, which continued throughout most of the summer.

Now, Chinese and foreign health officials say that some of those contested measures—more easily adopted by an authoritarian state—may have helped slow the spread of the disease in the world's most populous country. China has not had to cope with a crush of cases, and it began administering a vaccine for swine flu in early September, the first country to do so.

Foreign officials also say China demonstrated an unusual openness to sharing information about H1N1 with its citizens and other governments, in contrast to its secretive approach to the near pandemic of severe acute respiratory syndrome, or SARS, a few years ago.

That is not to say that China has been spared. On Tuesday, Health Ministry officials reported that there had been an “;explosive”; growth of H1N1 infection on the mainland because of the onset of winter, with 5,000 new cases in the previous three days pushing the total to more than 59,000.

At least 30 people have died here after contracting H1N1.

Exact data on the virus are hard to pin down; many more cases are suspected than confirmed, and countries often use different methods to identify cases. Still, the indications in China are much more positive than those in India. Like China, India has more than a billion people, many living in poor, rural conditions, and was exposed to the virus after it had been diagnosed in the West. The Indian Health Ministry has reported 505 deaths.

The United States, where the virus was spreading even before it was diagnosed in the spring, has reported more than 2 million cases and about 4,000 deaths in a population of 300 million.

“;I think there were a variety of measures put in place by different countries, and it's difficult to say what worked best and what didn't, but China's has worked very well, I think,”; said Michael O'Leary, the director of the Beijing office of the World Health Organization.

As of August, 56 million people had been screened for flulike symptoms at China's borders, said Feng Zijian, director of the emergency office of the Chinese Center for Disease Control and Prevention. Feng said he did not know the number of travelers who had been quarantined. The U.S. Embassy in Beijing said that 2,046 American citizens had been quarantined by the end of October, with 215 of those testing positive for H1N1.

“;If these strict measures had not been taken, and if there had been a sudden outbreak of the disease, there would have been a huge panic among the Chinese population,”; Feng said. “;Although there were many criticisms from outside, people should understand China's considerations.”;

But Feng and O'Leary also say that the social and financial costs of China's tough measures will have to be evaluated to see whether they were worth the benefits. And it is unclear how decisive those actions were in slowing the transmission of H1N1—the summer heat in much of China was likely a critical factor in slowing the spread, and most schools were out of session at the time.

Furthermore, some foreign health officials say China's methods for detecting cases of H1N1 are not as sophisticated as those in more developed countries, so the numbers in China could well be significantly underreported.

Some foreign officials are still skeptical of the need for the strict quarantine measures, saying that China should have re-evaluated its policies by June, when it was apparent that the disease was not as lethal as initially feared. The State Council, China's Cabinet, did not decide to relax the quarantine policy until July.

From the beginning, the WHO has said that tightening borders would not keep the disease out, and that closing borders or automatically quarantining specific groups of travelers—as China did for a brief period with holders of Mexican passports—would have no benefit.

Quarantines of entire school groups from overseas ignited outrage in the home countries and led some American officials to complain to the Chinese government. The State Department implicitly criticized the Chinese policies by issuing travel warnings on the quarantine procedures.

One of the most extreme cases took place in July, when a group of 65 students and seven chaperones from St. Mary's School in Oregon was quarantined twice, once in Beijing and once in Henan province. The first time came after a girl pulled aside at the airport tested positive for H1N1. Then in Henan, a boy running a high fever also tested positive, leading to a second quarantine session. During that time, a dozen students tested positive for H1N1. Most of the students and chaperons flew back to the United States on July 31, having spent 12 of 17 days of their trip in quarantine.

“;At the time, it seemed extreme, and it seemed restrictive, because I had never experienced an infectious disease outbreak,”; said Scott Dewing, director of technology at the school and one of the trip chaperones.

“;Now, looking back and seeing some of the measures that are being taken now in the U.S., the Chinese measures don't seem so extreme.”;

Chinese and Western officials say Chinese leaders put in place a comprehensive plan for a pandemic outbreak after the disastrous experience of SARS. This includes, at least in the first stages, some of the stringent quarantine measures of the SARS era, but also emphasizes educating the population about the disease: A red banner hanging from the balcony of a rural school building here in Guangdong province says: “;H1N1 flu is preventable, controllable and curable, and not terrifying.”;

The government was so anxious to stay ahead of H1N1 that officials decided in June to start developing a vaccine even though testing kits for measuring the dosage of the agent in the experimental vaccines had not arrived from the WHO, said Zhao Kai, a virologist who advises the government. It was an unusual step, but on Sept. 5 China became the first country to declare that it had discovered a vaccine, and by late October it had produced nearly 53 million doses.