WIKIMEDIA COMMONS | Science and policy experts tackled H5 influenza preparedness and response in a panel hosted by Georgetown's Global Health Institute and O'Neill Institute Nov. 15.
Science and policy experts from institutions across the United States came together to discuss the H5N1 influenza virus strain, also known as bird flu, in a webinar titled “Pandemic Influenza Vaccines: Responding to the H5 Outbreak & Preparing for the Future,” hosted by the Global Health Institute and the O’Neill Institute, a part of the Georgetown University Law Center that takes an interdisciplinary approach to national and global health law, Nov. 15.
The event consisted of four panels tackling different dimensions of influenza pandemic preparedness. Rebecca Katz, director of the Center for Global Health Science and Security and professor at Georgetown University, moderated the first panel, which focused on what is currently known about the virology and epidemiology of H5 flu strains. Speakers highlighted recent adaptations that have facilitated avian flu’s spread from domestic poultry to wild birds and mammals, which ultimately resulted in the arrival of this flu strain to the Americas in 2021.
Marcela Uhart, a veterinarian from the University of California, Davis, said a key indicator that mutations are occurring is the incidence of H5 viral infections throughout the year rather than solely during the typical winter flu season.
“We have a huge catalog of viruses that can mix and adapt in different hosts,” Uhart said at the event, with regard to numerous co-occurring influenza strains.
Uhart also emphasized the inequities that have already resulted from H5. For example, the burden of sampling wildlife often falls on equatorial countries that have the relevant animal hosts of the virus, and the process of obtaining these samples is both challenging and disruptive to local ecosystems.
“We have lost an excess of 680,000 birds to this point, only in the last year and a half or two, and nearly 60,000 mammals,” Uhart said. “If we only consider the Americas, North America is responsible for 80% to 90% of virus sequences even though it has only 10% of all the cases.”
Jennifer Nuzzo from Brown University’s School of Public Health said that, despite the relative mildness of H5 infections in humans thus far — possibly due to immunity conferred by exposure to previous influenza strains such as the 2009 swine flu, also known as H1N1 — there is still cause for concern, especially as the virus evolves. To illustrate this point, Nuzzo gave an example of a teenager in Canada who was recently hospitalized with H5N1 and remains in critical condition.
“We should not wait for severe illness to occur to take action to protect people from that possibility,” Nuzzo said.
Nuzzo also said that H5 is an occupational hazard for farm workers, who may be disincentivized to report infections and participate in surveillance programs due to concerns about losing their livestock. Nuzzo noted that some influenza strains can simultaneously infect the same animal host, leading to reassortment, a process of genetic exchange that could result in a more dangerous novel H5 strain. A novel strain of this nature would also have a disproportionate impact on health care workers, according to Nuzzo.
The second panel focused on the regulatory environment of H5 vaccines. Dr. Arnold Monto, a physician and professor emeritus of epidemiology and public health at the University of Michigan, spoke about the importance of increasing vaccination capabilities between influenza pandemics. As an example of a successful coordinated response among manufacturers and regulators, Monto discussed the H1N1 pandemic, which began in spring 2009. By September of that year, the U.S. Food and Drug Administration (FDA) had already approved four vaccines.
A new strain change proposal currently under review by the FDA would allow previous vaccine prototypes to be updated during the interpandemic phase so that safety and efficacy data would already be available if and when a pandemic breaks out.
Dr. David Kaslow from the FDA prompted further discussion about this expedited regulatory pathway. He said capitalizing on the interpandemic period to consolidate evidence about the safety and efficacy of updated vaccines is crucial.
“Coupled with better and better tools to forecast effective pandemic vaccine composition, we may save critical pandemic response time by having the updated vaccines we need without waiting for a strain change,” Kaslow said.
Dr. John Treanor, an infectious disease specialist who works for Tunnell Government Services, a consulting firm in the national health security space, highlighted various immune mechanisms that are being researched to allow for different approaches to vaccine development. For example, while inactivated vaccines contain killed versions of the virus and rely on inducing antibodies against it, live-attenuated vaccines contain weakened versions of the virus, which produce a closer reflection of the body’s natural immune response.
This type of vaccine often confers longer-lasting protection without the need for booster shots and may, therefore, be an easier route to achieving herd immunity, which is a threshold for broad community protection defined by a high enough percentage of people having acquired immunity. Treanor also emphasized that with any vaccine, developing it is only half the battle.
“Vaccine design is really just part of this whole response,” Treanor said. “Production, distribution, administration and sustainability all impact whether this is a successful response to controlling a pandemic.”