Trending Clinical Topic: Bird Flu

Ryan Syrek


May 13, 2022

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From the first case of H5 avian influenza in humans in the United States to reports of ongoing, widespread disease in birds, the potential of a possible pandemic variant has many keeping a watchful eye on the disease. The World Organisation for Animal Health (OIE) had warned in early 2022 that the current wave of bird flu had a greater risk of spreading to humans owing to the high number of variants. In late April, a state prison inmate who worked on a commercial poultry farm in Colorado tested positive for avian influenza A(H5) (see Infographic).

The man was helping kill poultry that probably had the H5N1 bird flu. The CDC stated that this does not change the risk for bird flu for the general public, which is considered low. However, they reiterated that people who work with birds should continue to take safety precautions, such as wearing gloves when handling birds and avoiding birds that appear to be dead or ill. The federal government says the H5N1 virus has been found in commercial and backyard birds in 29 states and in wild birds in 34 states since the first cases were detected in late 2021. Out of 2500 people exposed to birds infected with H5N1, only this one case of human infection has been confirmed.

China had previously recorded the first known human infection with the H3N8 strain of bird flu. A 4-year-old boy was found to have been infected with the virus after developing a fever and other symptoms on April 5. No close contacts were infected. Last year, China reported the first human case of H10N3. Many different strains of bird flu are present in China, with some sporadically infecting people, typically those who work with poultry.

Around the world, poultry are now being kept under a watchful eye. Egg-laying hens can no longer roam as freely, as farmers are temporarily keeping flocks inside during lethal outbreaks of bird flu. In France, the government has required farmers to keep chickens indoors since November. In the United States, bird flu has now spread into bald eagles. Over 30 bald eagles have died across more than a dozen states, according to the US Department of Agriculture. This is the worst outbreak of avian influenza since 2015.

A newly developed influenza vaccine against the H5N1 subunit of the avian influenza virus, which has pandemic potential, has been shown to be highly immunogenic in younger and older adults. In a randomized, phase 3, multicenter study, the experimental vaccine elicited high hemagglutination inhibition titers in patients. The study stratified 3196 participants into two age groups: those aged 18 to 64 years, and those aged 65 years or older. Each individual was given either two doses of vaccine or placebo 3 weeks apart on day 1 and day 22. Response was greater in young vaccine recipients. On day 43, almost 80% of participants aged 18-64 years and 54% of those aged 65 years or older had seroconverted and met the age-appropriate criteria for seroconversion rates.

From the first human cases of the current bird flu strain to preparations for a potential pandemic, avian influenza news garnered great interest this week, becoming the top trending clinical topic.

Learn more about avian influenza.


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