Although the United States has licensed vaccines for the H5N1 bird flu and millions of doses are stockpiled, these vaccines are not currently available to the general public.
Even after the country recorded its first human death from H5N1, federal health officials have not recommended widespread vaccination. The decision highlights a cautious approach influenced by the current low risk of person-to-person transmission and the potential downsides of rolling out a vaccine prematurely.
Avian influenza, commonly known as bird flu, is devastating commercial poultry and livestock across the United States, with Georgia recently detecting the virus in a poultry flock. To curb the spread, the state has halted poultry sales. Nationwide, egg prices are soaring, and grocery store shortages are becoming more common.
While most bird flu cases have been confined to animals, the virus has infected 67 people in the US since the outbreak began. Most cases caused mild illness, such as conjunctivitis or respiratory symptoms, but one Louisiana resident died from the virus in December. Globally, H5N1 has been far deadlier, with a historical fatality rate of about 50%. However, many of those deaths occurred in regions where close proximity to infected poultry led to higher exposure levels.
The US has approved three H5N1 vaccines since 2007, and millions of doses are stockpiled for emergency use. Two of the vaccines are effective against the current strain circulating in animals, and Moderna is developing new mRNA-based vaccines to enhance preparedness. Yet health officials, including those under the Biden administration, have refrained from deploying these vaccines. Experts emphasize that the current risk of widespread human infection is low, and no cases of person-to-person transmission have been identified.
Rolling out a vaccine too soon could have significant drawbacks. For example, adverse side effects could undermine public trust, as seen in 1976 when a rushed swine flu vaccination program was linked to rare cases of Guillain-Barré syndrome. For now, officials are monitoring the virus for mutations that could increase its transmissibility among humans, a scenario that would warrant more aggressive action.
Instead of vaccination, experts recommend preventive measures to protect at-risk populations, such as farm workers who handle infected poultry or livestock. The federal government is supplying personal protective equipment (PPE), including gloves, goggles, and respirators, to farms, and the antiviral drug Tamiflu is being made available to those exposed to the virus. Proper use of PPE and public education about avoiding contact with sick birds are considered essential for containment.
Elizabeth Strater of the United Farm Workers points out that the reluctance of farm workers to report illnesses—due to economic pressures—may obscure the true extent of infections. This makes it difficult to determine when human-to-human transmission might occur, a key trigger for vaccine deployment.
While human vaccination is not yet on the horizon, animal vaccines are gaining traction. The US Department of Agriculture has a national stockpile of H5N1 vaccines for poultry and is working to update these for the current strain. Vaccinating dairy cattle is also being explored, as this could reduce human exposure to the virus. Unlike poultry producers, who have resisted vaccination over export concerns and detection issues, the dairy industry appears more receptive, given the high economic value of cattle.
Though H5N1 currently poses a low public health risk, its potential to mutate remains a concern. The Department of Health and Human Services (HHS) has invested heavily in mRNA technology to speed up vaccine development if needed. Moderna, for example, is conducting trials of an investigational H5N1 vaccine and designing additional vaccines for future pandemic threats.
Seasonal flu vaccinations are also encouraged as a preventive measure. Coinfection with bird flu and seasonal flu viruses is rare but could lead to the emergence of a new, more dangerous strain. Increasing seasonal flu vaccination rates could help mitigate this risk.
