Biggerstaff Matthew, Reed Carrie, Swerdlow David L, Gambhir Manoj, Graitcer Samuel, Finelli Lyn, Borse Rebekah H, Rasmussen Sonja A, Meltzer Martin I, Bridges Carolyn B
Epidemiology and Prevention Branch, Influenza Division.
Modeling Unit and Office of the Director, and.
Clin Infect Dis. 2015 May 1;60 Suppl 1(Suppl 1):S20-9. doi: 10.1093/cid/ciu1175.
Human illness from influenza A(H7N9) was identified in March 2013, and candidate vaccine viruses were soon developed. To understand factors that may impact influenza vaccination programs, we developed a model to evaluate hospitalizations and deaths averted considering various scenarios.
We utilized a model incorporating epidemic curves with clinical attack rates of 20% or 30% in a single wave of illness, case hospitalization ratios of 0.5% or 4.2%, and case fatality ratios of 0.08% or 0.53%. We considered scenarios that achieved 80% vaccination coverage, various starts of vaccination programs (16 or 8 weeks before, the same week of, or 8 or 16 weeks after start of pandemic), an administration rate of 10 or 30 million doses per week (the latter rate is an untested assumption), and 2 levels of vaccine effectiveness (2 doses of vaccine required; either 62% or 80% effective for persons aged <60 years, and either 43% or 60% effective for persons aged ≥ 60 years).
The start date of vaccination campaigns most influenced impact; 141,000-2,200,000 hospitalizations and 11,000-281,000 deaths were averted when campaigns started before a pandemic, and <100-1 300,000 hospitalizations and 0-165,000 deaths were averted for programs beginning the same time as or after the introduction of the pandemic virus. The rate of vaccine administration and vaccine effectiveness did not influence campaign impact as much as timing of the start of campaign.
Our findings suggest that efforts to improve the timeliness of vaccine production will provide the greatest impacts for future pandemic vaccination programs.
2013年3月确认出现甲型H7N9流感所致的人类疾病，随后很快研制出候选疫苗病毒。为了解可能影响流感疫苗接种计划的因素，我们开发了一个模型，以评估在各种情况下避免的住院和死亡人数。
我们使用了一个模型，该模型纳入了疾病单波发作时临床发病率为20%或30%、病例住院率为0.5%或4.2%以及病死率为0.08%或0.53%的流行曲线。我们考虑了以下几种情况：疫苗接种覆盖率达到80%、疫苗接种计划的不同启动时间（大流行开始前16周或8周、大流行开始当周、大流行开始后8周或16周）、每周1000万或3000万剂的接种率（后一接种率为未经检验的假设）以及2种疫苗效力水平（需接种2剂疫苗；对于年龄<60岁的人群，疫苗效力为62%或80%有效，对于年龄≥60岁的人群，疫苗效力为43%或60%有效）。
疫苗接种活动的启动日期对影响最为关键；在大流行之前启动接种活动可避免14.1万至220万例住院和1.1万至28.1万例死亡，而在大流行病毒引入之时或之后启动的计划避免的住院病例数<100至130万例，死亡病例数为0至16.5万例。疫苗接种率和疫苗效力对活动影响的作用不如接种活动启动时间大。
我们的研究结果表明，提高疫苗生产及时性的努力将对未来的大流行疫苗接种计划产生最大影响。
