During a recent trip to a Mexico City hospital, Alejandro Macias, Mexico's special commissioner for influenza care, visited with two young children, both severely sick with the H1N1 flu. One boy was so ill he kept vomiting up the antiviral medications that had been prescribed to help make him better.
While the vast majority of H1N1 cases in Mexico are mild, Macias said similar scenes are being repeated around the city.
"The [total] influenza cases are lower numbers, but we are seeing a bigger proportion of children," said Macias. "I know what is happening in hospitals, I can tell you in these last months, the proportion of children is going up and up and up."
Mexico has confirmed nearly 66,000 cases of H1N1 since the epidemic started, and 642 deaths, 107 of which were in children under the age of 15.
While the Ministry of Health has not released an age break-down of recent cases, Guillermo Ruiz-Palacios, head of the department of infectious diseases at the National Institute of Medical Sciences and Nutrition, said the focus of concern has definitely shifted from young adults to young children.
"It was very consistent during the first wave that young persons between 20 to 35 years of age were the ones who were more likely to be affected," said Ruiz-Palacios. "We are seeing what we saw in these young adults, but now we are seeing them in children."
Due to new testing of samples taken in the spring, Ruiz-Palacios said it is now known that many of the more severe early cases in Mexico were a result of co-infections of both the H1N1 virus and parainfluenza.
Similarly, many of the cases of children in hospitals now are also due to co-infections he said, but this time with respiratory syncytial virus, a common cause of bronchiolitis and pneumonia in young children.
"The lesson from this is we should -- in severe cases -- test for other viruses as a routine procedure," said Ruiz-Palacios, so that correct medications can be prescribed for all the present viruses.
Another lesson Mexico's government and citizens have taken to heart from the spring outbreak is to seek professional medical treatment early when symptoms appear. Health officials credit this for helping cut the mortality rate of H1N1 cases from 1.7 percent in the first wave, to about 0.4 percent in the current wave.
"As Mexicans we are pretty prepared, we know exactly what to do. You go to the hospital as soon as you see the first symptoms and get a test," said Mexico City resident Monique Pinon. Her 12 year old daughter had a high fever and headache last week and was taken to the hospital, where she was diagnosed with H1N1. After being put on antiviral medication, her daughter recovered within days said Pinon.
In the United States, officials recommend adults with flu symptoms stay home unless they have underlying health conditions, or start to see severe illness, but in Mexico people are encouraged to see a doctor when the first signs of the flu hit, said Macias.
And unlike the U.S. Centers for Disease Control and Prevention, which states that most people with H1N1 do not need antiviral drugs, in Mexico they are being prescribed to all patients who present flu symptoms.
"We think it should be used very, very broadly," Macias said. "If you have fever and a cough that is enough to give the antiviral, you can't wait for the laboratory test."
The government has about 2 million antiviral treatments for H1N1 available and is ordering at least a million more, but distribution in some areas has been tricky because local authorities have been stockpiling the treatments instead of passing them on to health workers, said Macias.
The country received its first shipment of 865,000 H1N1 vaccines in late November, and has ordered 30 million total, but will likely not receive enough by the end of the year to extend beyond health care workers, pregnant women and very young children. The shortage of vaccine makes other forms of prevention, such as washing hands and keeping sick children home from school even more essential.
"We know it can be serious and if [a sick student] comes in with the slightest influenza symptoms it can quickly cause a domino effect and pass on their flu to others," said Alma Graciela Carrillo, a pre-school director in Mexico City.
"If it hadn't been for the outbreak in April we wouldn't have such strict hygiene measures... we were not accustomed to be so alert, to what the Ministry of Education or Health say, so it's been a collective learning process."
Macias acknowledged Mexico still has a long way to go in building up its critical care capacity, but said big strides have been made this year in improving facilities and training health workers to deal with emergencies.
"I feel that we still have many things to do-we still have to distribute more widely the antiviral, have doctors think more about [influenza], work harder with people not to self medicate with antibiotics, and improve our intensive treatment," said Macias.
"We could have done a better job, always, but I am proud of what we have done. We did the best we could with what we have."