28-05-2025
Recombinant Flu Shots Can Prevent Additional Hospital Stays
A recent analysis indicated that switching from the standard-dose inactivated influenza vaccine to the recombinant influenza vaccine (RIV) could have prevented nearly 100,000 hospitalizations among working-age adults in the United States over 10 seasons. The greatest benefits would have been seen in individuals aged 50-64 years and at-risk adults aged 18-49 years with chronic conditions.
METHODOLOGY:
Researchers investigated the burden of influenza and the potential impact of switching from the standard-dose inactivated influenza vaccine to RIV in reducing influenza-related hospitalizations among working-age adults in the United States, including those aged 18-49 years or 50-64 years.
They collected data on influenza burden, vaccine effectiveness, and coverage rates for both age groups from the US Centers for Disease Control and Prevention for the years 2012-2023, excluding 2020-2021.
The rates of influenza-related hospitalizations and deaths were estimated among adults aged 18-49 years or 50-64 years with at least one chronic medical condition.
A modeling analysis was carried out for both age groups to estimate the potential reduction in hospitalizations if RIV had replaced the standard-dose inactivated influenza vaccine, taking chronic conditions into account.
TAKEAWAY:
Over the past decade, influenza caused a median annual number of 151,021 hospitalizations and 7215 deaths among US adults of working age, with adults aged 50-64 years experiencing threefold and fivefold higher rates of hospitalizations and deaths, respectively, than those aged 18-49 years.
Among adults aged 18-49 years, the 14% with chronic conditions accounted for 28% of hospitalizations and 29% of deaths related to influenza. Similarly, among those aged 50-64 years, the 47% with at least one chronic condition accounted for 68% of hospitalizations and 69% of deaths related to influenza.
The modelling analysis indicated that a complete switch to RIV could have prevented a total of 87,654 (95% CI, 74,518-101,482) additional influenza-related hospitalizations over the past ten seasons among adults aged 50-64 years.
Similarly, among adults aged 18-49 years, a switch to RIV could have prevented a total of 14,436 (95% CI, 10,100-19,963) additional influenza-related hospitalizations over the same period.
IN PRACTICE:
'Considering the whole 50- to 64-year age group for the use of enhanced vaccines, like RIV, deserves consideration as it could support public health interventions promoting healthy aging,' the authors wrote. 'A risk-based recommendation may be more appropriate for younger working ages, given the fraction of burden within those with chronic conditions,' they added.
SOURCE:
The study was led by Laurence Torcel-Pagnon, MSc, Sanofi, Lyon, France. It was published online on April 17, 2025, in Clinical Infectious Diseases .
LIMITATIONS:
The vaccine effectiveness of RIV vs the standard-dose inactivated influenza vaccinevaries between seasons and studies, making it challenging to compare benefits across different scenarios. The analysis was limited due to a scarcity of high-quality evidence on clinical burden and vaccine effectiveness in at-risk groups. Lastly, the modeling approach used may not have considered indirect effects that influenced vaccination at the population level.
DISCLOSURES:
This study was funded by Sanofi. The authors reported being employees of Sanofi and potentially holding shares in the company.
