Current Status of Live Attenuated Influenza Vaccine in the United States for Seasonal and Pandemic Influenza

Christopher S. Ambrose; Catherine Luke; Kathleen Coelingh


Influenza Resp Viruses. 2008;2(6):193-202. 

In This Article

Safety Concerns With Pandemic LAIV Viruses

The development of live attenuated viruses with the surface glycoproteins of avian influenza viruses or other influenza viruses of pandemic potential (e.g., H2 viruses) raises the concern that these viruses may reassort with circulating seasonal influenza viruses, and thereby generate easily transmissible viruses with novel HA and NA. Although preliminary data from clinical studies suggest that the pLAIV viruses generated so far are highly restricted in replication, this remains a significant concern for regulatory authorities. During development of these vaccines, the risk of reassortment can be mitigated by conducting clinical trials in an inpatient setting during months when influenza viruses are not likely to be circulating. The clinical studies of pLAIV viruses currently being conducted in the United States are performed in an isolation facility between April and the beginning of December. In the case of the threat of an influenza pandemic, the risk of reassortment must be weighed against the benefits of administering such a vaccine to the population before proceeding with widespread use of a live vaccine. Implementation of a live attenuated pandemic influenza vaccine would be based on the recommendation of public health authorities.

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