Seroprotection rate and seroconversion rate of older adults are lower than those in younger adults influenza virus infection

Objectives:
Older people (≥60 years old) are particularly vulnerable to influenza virus infection and vaccine is effective in reducing the disease burden in this population. However, it remains obscure whether their antibody response is lower than those of younger adults (18-60 years old). Therefore, this review article has been conducted.

Have older people (≥60 years old) a lower antibody response to influenza virus infection than younger adults (18-60 years old)?

Study design:
This review article included 6 RCTs with a  total of 7,976 participants.

Results and conclusions:
The investigators found for the seroprotection rate (SPR) the pooled risk ratio (RR) was 0.92 [95% CI = 0.90 to 0.94, I2 = 66%, p 0.0001] for A/H1N1 and 0.94 (95% CI = 0.90 to 0.98, I2 = 91%, P = .002) for B/Victoria and the antibody responses of A/H3N2 and B/Yamagata were similar in the two age groups.

The investigators found for the seroconversion rate (SCR), the pooled RR was 0.85 [95% CI = 0.76 to 0.94, I2 = 93%, p = 0.003], 0.77 [95% CI = 0.66 to 0.91, I2 = 94%, p = 0.002] and 0.83 (95% CI: 0.71-0.96, I2 = 94%, p = 0.02] for A/H1N1, B/Victoria and B/Yamagata, respectively and the antibody responses of A/H3N2 were similar in the two groups.

The investigators found some variations in the antibody responses across virus types and subtypes after influenza vaccination.

The investigators concluded the seroprotection rate (SPR) and the seroconversion rate (SCR) of older adults (≥60 years old) are lower than those in younger adults (18-60 years old) for A/H1N1 and B/Victoria, while the two age groups have similar antibody responses for A/H3N2. But, the antibody responses to vaccines are not associated with real-world vaccine effectiveness (VE), indicating that antibody response might not fully reflect the vaccine effectiveness of A/H3N2.

Original title:
Immunogenicity of influenza vaccine in elderly people: a systematic review and meta-analysis of randomized controlled trials, and its association with real-world effectiveness by Meng Z, Zhang J, [...], Yang X.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/32347787

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