The 2009 pandemic was a bit of a surprise. While all eyes were on Asia, the virus emerged from our own backyard.

A never-before-seen flu virus was found in a 10-year-old California boy on April 15, 2009. Two days later, the same virus was identified in an 8-year-old boy living about 130 miles away. Shortly thereafter, the virus was discovered in far ranging locations such as Texas, New York, Canada and Mexico. Obviously, it was spreading human to human. An alarm was sounded.

This flu strain was new and resulted from the combination of two pig strains and a human strain. The origin was traced to factory farms in Mexico, although this remains somewhat controversial.

First, the virus was called the swine or pig flu, but world leaders thought the name was problematic because of concern that Jews and Muslims might refuse any forthcoming vaccine because of the reference to pigs. It was also termed the Mexican flu, but the name was discouraged as offensive. The U.S. Centers for Disease Control and Prevention settled on calling it the “novel H1N1 flu,” but its official name was influenza A/California/07/2009.

Within two months of its detection, novel H1N1 had spread to over 70 countries. The World Health Organization declared a pandemic. Travel warnings went out discouraging unnecessary visits to Mexico. Australia ordered a cruise ship to stay at sea. Egypt quarantined those returning from Mecca. China confined a group of visiting U.S. students. Travel bans and quarantines stopped as it became clear that novel H1N1 was already too widespread.

Based on an increase in flu-related deaths in Mexico, the CDC projected soaring U.S. hospitalizations and the deaths of thousands. Highest risk were likely to be the very young and very old, pregnant women and individuals with certain medical conditions. The forecast was that upwards of 40 percent of the workforce could be out because of illness or caring for ill family members. News that the government had stockpiled millions of courses of anti-viral drugs was reassuring.

Conversely, concern grew with the discovery of a drug-resistant strain in a stricken nursing home.

In the case of a severe outbreak, the CDC advised schools and universities to have a plan for closure. By the end of the pandemic, about 600 schools across 19 states had closed temporarily.

Work on a vaccine started almost immediately. Vaccine candidates followed the seasonal flu approval pathway to bypass lengthy human testing. This pathway necessitated growing vaccine virus in chicken eggs. Advanced technologies that could quickly produce more vaccine doses were rejected because they would’ve required prolonged human trials. The first vaccines were licensed by the Food and Drug Administration in September.

Vaccines became largely available in November. Because of supply limitations, doses were targeted at young children, pregnant women, those with high-risk conditions and health care providers. Supplies became adequate to vaccinate the public in early 2010. Cases tapered off and the pandemic was declared over in April 2010. Novel H1N1 became a circulating seasonal flu and has been covered by the seasonal flu vaccine ever since.

Post-pandemic analysis revealed that novel H1N1 was no more severe than seasonal flu. The risk of serious complications wasn’t elevated in either children or adults.

An additional finding was that vaccines played almost no role in stemming the pandemic because supplies were so limited. Learning a lesson, the government invested billions to improve our capability to rapidly produce flu vaccines should a new strain of influenza again threaten the world.

Vaccine Smarts is written by Sealy Institute for Vaccine Sciences faculty members Drs. Megan Berman, an associate professor of internal medicine, and Richard Rupp, a professor of pediatrics at the University of Texas Medical Branch. For questions about vaccines, email

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(1) comment

Bailey Jones

Thanks for this perspective on H1N1. A few weeks ago I heard an interview on NPR concerning your last sentence. The US now maintains, in secret locations around the country, 100,000s of chickens, ready to lay eggs to make the next flu vaccine.

I think this well illustrates the situation we are in. We've seen enough flu that we're relatively ready for it. But these new SARS viruses are something we don't have a handle on yet. I hope the mistakes of the past few months will be the impetus for new research and new policies, and not just be swept under the rug as we declare, as we are wont to do, "Mission Accomplished".

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