Fox Annette, Sánchez-Ovando Stephany, Carolan Louise, Hadiprodjo A Jessica, Chen Yuyun, Ho Faith, Cheng Samuel M S, Thompson Mark G, Iuliano A Danielle, Levine Min Z, Valkenburg Sophie A, Ip Dennis K M, Peiris J S Malik, Sullivan Sheena G, Cowling Benjamin J, Leung Nancy H L
Department of Infectious Diseases, University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Australia.
Victorian Infectious Diseases Reference Laboratories, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Australia.
Clin Infect Dis. 2025 Apr 3. doi: 10.1093/cid/ciaf060.
Influenza vaccine effectiveness can be reduced in older adults and among repeatedly vaccinated groups. Results from year 1 of "PIVOT," a randomized trial among adults aged ≥65 years in Hong Kong, showed that adjuvanted (Adj), high-dose (HD), and recombinant hemagglutinin (rHA) vaccines induced greater antibody responses against vaccine viruses than standard-dose (SD) influenza vaccine. Here, we examine the breadth of A(H3N2)-reactive antibodies induced during the first 2 study years (2017/2018, 2018/2019), and compare participants who received influenza vaccination annually, or not at all, for 5 years preceding enrollment.
14-20 PIVOT participants per vaccine and prior vaccination group (0/5 or 5/5 prior years) who provided sera on days 0, 30, and 182 in year 1 and days 0 and 30 in year 2 were assessed. Hemagglutination inhibition (HAI) antibody titers were measured against 30 viruses spanning 1968 to 2018.
In year 1, rHA and Adj but not HD vaccines induced titers ≥40 and titer rises ≥4-fold (seroconversion) against significantly more strains than SD vaccine among participants vaccinated 0/5 prior years. Only rHA and Adj vaccines induced titers ≥40 against post-vaccine strains. Antibody responses were poor among participants vaccinated 5/5 compared with 0/5 prior years and only rHA increased the breadth of seroconversion compared with the SD vaccine in this group. Antibody responses were weaker across groups in year 2.
The results suggest that Adj and particularly rHA vaccines may improve the breadth of protection against A(H3N2) viruses but may not overcome attenuating effects of repeated vaccination in older adults.
NCT03330132.
在老年人和多次接种疫苗的人群中，流感疫苗的有效性可能会降低。“PIVOT”（一项针对香港65岁及以上成年人的随机试验）第一年的结果显示，与标准剂量（SD）流感疫苗相比，佐剂（Adj）、高剂量（HD）和重组血凝素（rHA）疫苗诱导产生的针对疫苗病毒的抗体反应更强。在此，我们研究了在研究的前两年（2017/2018年、2018/2019年）期间诱导产生的A（H3N2）反应性抗体的广度，并比较了在入组前5年每年接种流感疫苗或从未接种过疫苗的参与者。
评估每种疫苗和既往接种组（既往0/5年或5/5年）中14 - 20名PIVOT参与者，这些参与者在第1年的第0天、第30天和第182天以及第2年的第0天和第30天提供了血清。针对1968年至2018年的30种病毒测量血凝抑制（HAI）抗体滴度。
在第1年，对于既往0/5年接种疫苗的参与者，rHA和Adj疫苗而非HD疫苗诱导产生的滴度≥40且滴度升高≥4倍（血清转化）的毒株数量显著多于SD疫苗。只有rHA和Adj疫苗诱导产生的针对疫苗后毒株的滴度≥40。与既往0/5年接种疫苗的参与者相比，既往5/5年接种疫苗的参与者的抗体反应较差，并且在该组中只有rHA与SD疫苗相比增加了血清转化的广度。在第2年，各组的抗体反应均较弱。
结果表明，Adj疫苗尤其是rHA疫苗可能会提高针对A（H3N2）病毒的保护广度，但可能无法克服老年人重复接种疫苗的减弱效应。
NCT03330132。
