Dagan Ron, Juergens Christine, Trammel James, Patterson Scott, Greenberg David, Givon-Lavi Noga, Porat Nurith, Gruber William C, Scott Daniel A
Faculty of Health Sciences, Ben-Gurion University of the Negev, POB 151, Beer-Sheva 84101, Israel.
Pfizer Pharma GmbH, Linkstrasse 10, 10785 Berlin, Germany.
Vaccine. 2017 Feb 7;35(6):945-950. doi: 10.1016/j.vaccine.2016.12.052. Epub 2017 Jan 11.
In addition to reducing vaccine-type nasopharyngeal carriage rates, pneumococcal conjugate vaccines (PCVs) may decrease carriage density in vaccinated individuals still carrying vaccine serotypes. However, reduction of carriage density has not been systematically studied. This study compared the effect of PCV13 versus PCV7 on carriage density of the serotypes in PCV13 that are not included in PCV7.
This randomized, double-blind study was conducted in southern Israel and included Jewish and Bedouin subjects. Per protocol, 881 and 873 infants received PCV13 and PCV7, respectively, at ages 2, 4, 6, and 12months. Nasopharyngeal cultures at ages 7, 12, 13, 18, and 24months were plated using the 4-quadrant semiquantitative method and graded 0 (negative) to 4 (growth in all plate quadrants). In this post hoc analysis, the least squares means of cumulative colonization densities per serotype and serotype combination of the total population and each ethnic subpopulation in each vaccine group were calculated, and differences between vaccine groups derived from a linear model.
PCV13-vaccinated children still carrying the 6 additional PCV13 serotypes unique to PCV13 showed no significant differences in carriage density compared with the PCV7-vaccinated control group. No differences in carriage density were shown between Jewish and Bedouin subpopulations despite higher carriage rates among Bedouin subjects.
Although PCV13 vaccination reduces vaccine-type carriage compared with PCV7 vaccination by reducing nasopharyngeal acquisition of the additional PCV13 serotypes as previously reported, the current study lacks evidence of a decrease in carriage density of these serotypes when acquired in vaccinated children. Despite the lack of effect on carriage density observed, surveillance data suggest a dramatic decrease in disease rates after PCV implementation. Thus, the current analysis suggests that PCV's impact on carriage density has minimal or no impact on vaccine success. (www.ClinicalTrials.gov: NCT00508742).
除降低疫苗型别鼻咽部携带率外，肺炎球菌结合疫苗（PCV）还可能降低仍携带疫苗血清型的接种个体的携带密度。然而，携带密度的降低尚未得到系统研究。本研究比较了PCV13与PCV7对PCV13中不包含在PCV7中的血清型携带密度的影响。
这项随机、双盲研究在以色列南部进行，纳入了犹太和贝都因受试者。按照方案，分别有881名和873名婴儿在2、4、6和12月龄时接种了PCV13和PCV7。在7、12、13、18和24月龄时采集鼻咽部培养物，采用四象限半定量方法接种平板，并分级为0（阴性）至4（所有平板象限均生长）。在这项事后分析中，计算了每个疫苗组中总人群和每个种族亚组每种血清型和血清型组合的累积定植密度的最小二乘均值，并通过线性模型得出疫苗组之间的差异。
仍携带PCV13特有的另外6种PCV13血清型的接种PCV13的儿童，与接种PCV7的对照组相比，携带密度无显著差异。尽管贝都因受试者的携带率较高，但犹太和贝都因亚组之间的携带密度没有差异。
如先前报道，与接种PCV7相比，接种PCV13可通过减少额外PCV13血清型的鼻咽部获得来降低疫苗型别携带率，但本研究缺乏证据表明这些血清型在接种儿童中获得时携带密度会降低。尽管未观察到对携带密度的影响，但监测数据表明PCV实施后疾病发生率大幅下降。因此，当前分析表明PCV对携带密度的影响对疫苗效果的影响很小或没有影响。（www.ClinicalTrials.gov：NCT00508742）
