Vaccine response to the 2015-2016 HPAIV outbreaks in the United States

Authors: Suarez, David; Thacker, Eileen

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/15/2018
Publication Date: 10/18/2018
Citation: Suarez, D.L., Thacker, E.L. 2018. Vaccine response to the 2015-2016 HPAIV outbreaks in the United States. Meeting Proceedings. CDROM.

Interpretive Summary: Vaccination for the control of both LPAI and HPAI has been increasing worldwide because of the increasing number of outbreaks worldwide. Vaccines can be used to just control clinical disease, but in some situations it can also aid in the eradication of avian influenza from a country. In general, a good antigenically matched vaccine can prevent clinical disease and greatly reduce virus shedding in vaccinated flocks that do become exposed to the virus. The reduction of virus shedding allows the opportunity for vaccines to help break the transmission chain, and help eradicate the virus from a country. For eradication to be the goal, a country has to have a good veterinary infrastructure, increased biosecurity, increased surveillance, and properly manage animal movements. Unfortunately most countries that vaccinate have been poorer countries that are vaccinating with the goal of only reducing clinical disease.

Technical Abstract: Using two representative viruses, a H5N8 and related reassortant H5N2 virus, studies were designed using both killed adjuvanted vaccines and commercially available viral vector vaccines. The killed vaccines included several North American seed strain viruses, an autogenous vaccine, and several Chinese vaccines that were created using reverse genetics technology. In challenge studies the autogenous vaccine provided the best protection based on clinical disease and virus shedding. One of the Chinese vaccines also provided good protection, but that vaccine is not licensed for use in the U.S. The other vaccines either did not provide adequate protection from mortality (>90%) or had high levels of virus shedding after challenge. The autogenous vaccine, because it is made with a HPAI virus, couldn’t be commercially produced in the U.S. which meant that none of the existing vaccines were recommended if vaccination was to be a control option. Alternative vaccines were developed using reverse genetics technology that attenuated the H5 HPAI virus resulting in a safe autogenous vaccine, and a RNA particle vaccine made from an alphavirus vector system. Both vaccines worked well in challenge studies and both were licensed and purchased by the National Veterinary Stockpile.