Bird Flu Vaccine Trial May Offer Hope for Protecting Hawaiian Monk Seals

In response to the increasing threat of bird flu, marine mammal researchers are hoping to provide a life-saving, preventative vaccine for endangered Hawaiian monk seals. Learn how researchers at The Marine Mammal Center are studying the bird flu vaccine in elephant seals as a similar species, as well as our next steps to protect Hawaiian monk seals.

As the world’s largest marine mammal hospital, experts at The Marine Mammal Center learn an extraordinary amount of information from our seal, sea lion and sea otter patients. Our researchers monitor long-term changes in animal health and also identify emerging diseases that present population-wide threats to marine mammals or threats to human health.

In a critical effort to monitor bird flu in marine mammals, we are constantly assessing our patients for any signs of the virus and collecting samples at our hospital facilities in California and Hawai‘i. While our patients have all fortunately tested negative for the virus so far, researchers have grown increasingly concerned for the future of the Hawaiian monk seal population.

In addition to preventing the spread and severity of dangerous diseases in humans and pets, vaccination is also an effective conservation tool that can be used to save endangered wildlife. In fact, a highly successful vaccination program for Hawaiian monk seals has been in place by the National Oceanic and Atmospheric Administration (NOAA) since 2016 to reduce the risk of morbillivirus infection, a contagious and deadly group of viruses that includes canine distemper and human measles. And recently, the crucial effort to immunize critically endangered California condors from the current H5N1 strain of avian influenza was conducted by U.S. Fish and Wildlife Service (USFWS) and U.S. Department of Agriculture (USDA).

Now, these established vaccination programs for other diseases and wildlife species provide effective roadmaps for our researchers to protect Hawaiian monk seals from bird flu. Led by Dr. Sophie Whoriskey, the Center’s Associate Director of Hawai‘i Conservation Medicine, our groundbreaking collaborative project is currently underway to study and potentially provide this species with a life-saving, preventative vaccine.

The Center’s veterinary experts monitored the seals closely throughout the trial for any reactions, as well as their overall health and wellbeing. None of our patients experienced any severe reactions, such as an unexpected allergic reaction or infection at the injection site, but our veterinary care team was well-prepared with strict criteria for response if necessary.

Most adverse reactions to vaccines are mild and short-lived, like minor discomfort and swelling at the injection site. As vaccines work by safely mimicking an infection and helping the body learn to defend itself, these minor reactions can be positive signs that the immune system is responding appropriately.

While the rescued elephant seals in this study were all well on the road to recovery when the trial began, other underlying conditions can sometimes arise in our patients and unfortunately change their prognosis. Prior to the trial ending, one patient in the placebo control group died suddenly and unexpectedly. Although this animal had only received an injection of sterile saline, not the bird flu vaccine, a thorough safety investigation was conducted. This patient’s cause of death is still being assessed, but researchers were able to rule out any connection to the vaccine trial.

The Center performs a necropsy, or animal autopsy, on every patient that dies at the hospital, and tissue samples are collected for further studies. This is critical in helping scientists better understand why marine mammals die, identifying patterns for different threats and diseases, and developing life-saving treatments.

While the study is still being evaluated, researchers are encouraged by early results, and the bird flu vaccine seems to be safe in our elephant seal patients. Our next step is to understand the vaccine’s efficacy (how well the vaccine works to prevent viral infection in a controlled environment).

Blood samples were collected multiple times throughout the trial from the seals that received the active vaccine and those that received saline placebo injections. To identify the animals’ immune responses to the vaccine, researchers will measure and compare the levels of antibodies in the blood, which are protective proteins produced by the immune system. If the seals that received the vaccine have produced the specific antibodies, our researchers can determine whether they have developed protective immunity to bird flu.

With more than 50 years of experience advancing marine mammal and ocean health, the Center’s conservation work is crucial to the survival of endangered Hawaiian monk seals. As we continue gathering and evaluating results from the bird flu vaccine trial, researchers are hopeful that our findings can be used to save this species from a potential outbreak. If the vaccine proves to be protective in elephant seals as a similar species, we can help make scientifically supported decisions about our next steps and recommendations for immunizing Hawaiian monk seals.

“Locally on the Hawaiian Islands, our hope is to use the bird flu vaccine as a preventative tool to protect Hawaiian monk seals from an extinction-level outbreak,” said Dr. Whoriskey. “And if we can use this tool to protect an endangered population, this paves the way for similar conservation efforts worldwide.”

The Center’s experts are leading contributors to global knowledge about marine mammal health, developing innovative medical techniques and conducting vital research. As bird flu continues to threaten humans and animals around the world, including endangered populations, our work to study and potentially immunize Hawaiian monk seals can inform global efforts to protect ocean health and biodiversity.