Systematic review of influenza vaccine effectiveness against laboratory-confirmed influenza among older adults living in aged care facilities

ABSTRACT

We estimated the effectiveness of influenza vaccines in preventing laboratory-confirmed influenza among older adults in aged care. Electronic database searches were conducted using search terms, and studies were selected as per the selection criteria. Fourteen studies were included for final review. The studies exhibited considerable variation in reported vaccine effectiveness (VE) across different seasons. Among the observational studies, VE ranged from 7.2% to 89.8% against laboratory-confirmed influenza across different vaccines. Randomized clinical trials demonstrated a 17% reduction in infection rates with the adjuvanted trivalent vaccine. The limitations include the small number of included studies conducted in different countries or regions, varied seasons, variations in diagnostic testing methods, a focus on the A/H3N2 strain, and few studies available on the effectiveness of enhanced influenza vaccines in aged care settings. Despite challenges associated with achieving optimal protection, the studies showed the benefits of influenza vaccination in the elderly residents.

KEYWORDS:

• Vaccine effectiveness
• aged care residents
• nursing home
• long-term care
• laboratory-confirmed influenza

Disclosure statement

CRM receives funding from Sanofi for investigator-driven research on influenza epidemiology, which funds the salary of author AM. Others declare that they have no conflicts of interest..

Author contributions

Aye Moa: Initial draft, methodology, review & editing.

Mohana Kunasekaran: Initial draft, methodology, review & editing.

Zubair Akhtar: Methodology, review & editing.

Valentina Costantino: Methodology, review & editing.

C. Raina MacIntyre: Conceived the study, methodology, supervision, writing, review & editing.

Additional information

Funding

Authors MK, ZA and VC are supported by funding from the Balvi Filantropik Fund. C. Raina MacIntyre is supported by a NHMRC Principal Research Fellowship, grant no. [1137582] and NHMRC Investigator Grant [2016907].