January 19, 2010 — A型流感（H1N1）2009單價疫苗的供應由J. A. Singleton碩士以及來自美國疾病管制局（CDC）的同事，於1月15日發表在發病與死亡率週報上描述。現在A型流感（H1N1）2009單價疫苗供應充足，CDC已經擴展疫苗接種建議，從原先的目標族群擴大到其他族群，包括65歲以上老年病患。
H1N1 2009 Monovalent Vaccination Recommended for Overall Population
By Laurie Barclay, MD
Medscape Medical News
January 19, 2010 — Influenza A (H1N1) 2009 monovalent vaccination coverage in the United States from October to December 2009 is described in an early release report published January 15 by J. A. Singleton, MS, and colleagues from the US Centers for Disease Control and Prevention in the Morbidity and Mortality Weekly Report. Now that an ample supply of influenza A (H1N1) monovalent vaccine is available, the CDC has expanded the recommendation for vaccination from the initial target groups to the rest of the population, including those older than 65 years.
When vaccine supply was limited, initial target groups and those in a limited vaccine subset of those groups originally had priority for receipt of influenza A (H1N1) 2009 monovalent vaccine. According to the CDC, 20.3% of the US population had been vaccinated in 2009, including 27.9% of persons in the initial target groups and 37.5% in the limited vaccine subset, as well as an estimated 29.4% of US children aged 6 months to 18 years.
Although estimates of 2009 H1N1 vaccination rates were generally higher among non-Hispanic whites than among non-Hispanic blacks, this difference was statistically significant only among adults aged 25 to 64 years with high-risk conditions.
Limitations cited in an accompanying editorial note include data collected during a single week of interviews, all results based on self-report or parental report, limited sample size, possible selection bias, and low response rates.
"The epidemiology of 2009 H1N1 influenza over the months ahead is unknown, but another rise in incidence, as occurred during the winter of the 1957–58 pandemic, remains possible," the editorialists write. "In addition, increases in influenza activity from seasonal influenza also might occur as the season progresses. Vaccination remains the best way to prevent influenza infection and influenza-related hospitalizations and deaths."
The CDC estimates that from April to December 12, 2009, there were about 55 million cases of 2009 H1N1, about 246,000 H1N1-related hospitalizations, and about 11,160 2009 H1N1-related deaths.
Follow-up on Vaccine Safety
A follow-up communication on the November 10, 2009, Dear Healthcare Professional letter from Margaret Hamburg, MD, commissioner of the US Food and Drug Administration (FDA), updates the FDA/CDC experience with the H1N1 vaccination program and gives some detail regarding the current vaccine safety monitoring program.
An FDA/CDC analysis of 3783 reports of adverse events submitted to the Vaccine Adverse Event Reporting System through November 24, 2009, showed no substantial differences between H1N1 and seasonal influenza vaccines in the proportion or types of serious adverse events reported, nor was there any increase in Guillain-Barre syndrome or any of the other preselected adverse events under surveillance.
Of the adverse events reported to the Vaccine Adverse Event Reporting System, 94% were classified as "non-serious," such as soreness at the vaccine injection site.
"To date, our experience with the H1N1 influenza vaccination program has met high safety expectations, based on the track record of the licensed seasonal vaccines, including live attenuated and inactivated vaccines," the letter states. "We are also collaborating with other agencies around the world to share our vaccine safety information and experiences. Should any safety concerns arise, we will evaluate them thoroughly and bring them to the public's attention quickly."
The letter notes a significant possibility that H1N1 influenza will return and that California, Georgia, Hawaii, Indiana, Maine, Nevada, New Hampshire, New Jersey, New Mexico, New York, Tennessee, and Virginia continue to report regional influenza activity.
"Therefore, it is still important to vaccinate people in high-risk groups as soon as H1N1 vaccine is available in their communities, and people who are not in high-risk groups should get a vaccine when it becomes available to them," the letter concludes.
"As more vaccine has become available, we encourage you to continue to talk with your patients about the benefits and risks of H1N1 vaccines especially for pregnant women and others at high risk of severe influenza infection and its complications. While antiviral resistance remains at low levels, future potential development of resistance is still a concern, so immunization is the best protection. "
