Exploring the Plausibility of a Fungal Pandemic as Depicted in HBO's 'The Last Of Us

Fungal infections are on the rise in the United States, and unlike bacterial or viral illnesses, there is no vaccine to protect against them. While a fungal infection similar to the one in HBO's "The Last of Us" is not expected to wipe out humanity, these infections are a cause for concern.

Fungi can cause a wide range of illnesses, from irritating athlete's foot to life-threatening bloodstream infections. According to the Centers for Disease Control and Prevention, fungal infections are responsible for more than 75,000 hospitalizations and nearly 9 million outpatient visits each year in the US, and around 7,200 people died from fungal diseases in 2021.

One type of fungus, Candida auris, is resistant to all drugs used to treat it and is particularly dangerous for hospitalized and nursing home patients. Climate change threatens to make several infection-causing fungi more widespread, such as the fungus that causes Valley fever, which thrives in hot, dry soil.

Despite the growing threat, there are currently no licensed vaccines to prevent fungal infections. An immunologist and vaccine expert at the University of Georgia, Karen Norris, said that "these are the most important infectious diseases that you have not heard of." A vaccine has the potential to protect a large swath of individuals, and ultimately the goal is to develop a single vaccine that protects against all fungal infections.

However, a "pan-fungal" vaccine is incredibly challenging to make since, unlike Covid vaccines that target a single pathogen, a fungal vaccine would ideally protect against the wide spectrum of fungi in existence, each biologically different from the next. Nonetheless, Norris and her team have decided to focus on the three fungi responsible for the vast majority of fatal fungal infections in the US: Aspergillus, Candida auris, and Pneumocystis.

In preclinical trials, the experimental vaccine developed by Norris and her team was shown to generate antifungal antibodies in animals, including rhesus macaques. With funding support, the researchers could start and finish the human vaccine trials within the next five years.

In Arizona, researchers are focused on a vaccine to prevent Valley fever, a lung infection caused by the fungus Coccidioides. The fungus is an "emerging threat" because climate change is expanding its range. So far, the vaccine has been shown to be effective in dogs, according to John Galgiani, the director of the Valley Fever Center for Excellence at the University of Arizona College of Medicine.

While experts know which fungi to target, vaccine development has been slow, mostly due to a lack of funding. Respiratory viruses such as those that cause Covid, the flu, or measles infect millions of people and lead to thousands of hospitalizations worldwide each year. By comparison, hundreds of species of fungi can cause illness in people, but the most common ones are non-life-threatening.

Valley fever is usually limited to the Southern and Western regions of the US and is usually serious for people with weakened immune systems. Most people breathe in Aspergillus every day without getting sick, but it can be life-threatening for people with cystic fibrosis or asthma. Candida auris infections have been mostly limited to healthcare settings, and they pose the biggest threat to very sick patients.

As a result, many in public and private spaces do not see fungal vaccines as a "critical unmet need." Galgiani said it could take eight years before a fungal vaccine is made available in the US. However, awareness of climate change's impact on fungal infections could prompt increased funding support and lead to a fungal vaccine being developed sooner.