Cell-culture–Derived Influenza Vaccine Is Safe and Efficacious

Mary E. Wilson, MD


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In This Article

Abstract and Introduction


A Vero-cell-culture–derived trivalent influenza vaccine had a protective efficacy of 79% against antigenically matched influenza strains.


Conventional egg-based influenza vaccines have several drawbacks, including a lengthy production period that limits the capacity to match the vaccines to currently circulating virus strains. In a recent phase III trial conducted at 36 centers in the U.S., researchers (with partial vaccine-industry support) assessed the safety and efficacy of a cell-culture–derived influenza vaccine. They also sought to determine whether correlates of protection observed with egg-derived vaccines were similar for this tissue-culture–derived product.

A total of 7250 healthy adults aged 18 to 45 were randomized to receive Vero-cell–derived vaccine (formulated to contain 15 µg of hemagglutinin antigen from each of the three virus strains for the 2008–2009 influenza season) or buffered saline in early December 2008. Beginning 18 to 24 days after vaccination, participants with influenza-like illness had nasopharyngeal swab specimens taken ≤48 hours after symptom onset. Follow-up continued through May 15, 2009.

Of 104 specimens that tested positive for influenza virus, 73 were isolated in cell culture and matched the vaccine antigens. The protective efficacy against antigenically matched strains was 79% overall (79% for A/H1N1, 50% for A/H1N2, 100% for influenza B). As seen with egg-based vaccines, a hemagglutinin titer ≥1:15 correlated with immunity. The number of severe adverse events was similar between the vaccine and placebo groups.