Anthrax has been mentioned within the XNDUIW lore, considering that infection generally occurs by contact with the skin, or if it's digested, though the most lethal outcome is from inhalation too. Several actors have used the disease as a weapon, which has been used in biowarfare and bioterrorism as well, considering that it has been a major factor within the lore as such, considering that it is a very well-known disease.
Anthrax itself is not really common in developed countries, though it is found globally, in regions where livestock are not frequently vaccinated, which makes it more common in developing countries regardless. Unlike the flu however, anthrax is not contagious, and cannot be transmitted from person to person, though it can infect someone via a cut on the skin or from animals, as it is a zoonotic disease, meaning that it's transmitted from animals to humans.
Within XNDUIW
Anthrax has been mentioned within the XNDUIW lore, considering that it is often used as a bio-weapon, though it's presence is extremely rare, and it can only be transmitted to multiple people concurrently if they are exposed to sick animals or maliciously spread from a container. It cannot be transmitted from person to person, though the effects of anthrax can be severe, though it is not capable of becoming a pandemic-level illness like COVID-19 either way. The first mentions of anthrax within XNDUIW date back to around 2015, especially in the so-called "anthrax letter", which was spread in a criminal matter, which led to a couple of hospitalizations and deaths, though incidents have occurred since the 9/11 attacks, especially when such letters are often intercepted by security personnel either way.
In general, you will not see anthrax commonly in cities or the vast majority of regions, as despite the rather grave symptoms this disease causes, it is extremely rare, as the disease, which is commonly known as Bacillus anthracis, can cause serious and potentially fatal symptoms which is highly toxic, as it is classed as a "Type 1 biological agent", with it's spores being extremely durable in the environment too. It is more prevalent in farms and agricultural regions where it can infect livestock and even wildlife as well, though strict measures done by both the Canadian and American governments have encouraged the vaccination of livestock and even farm animals against the disease too regardless of whatever was done. You will never see anthrax pop up in roleplay in-game most of the time within XNDUIW, given how rare it is, though it can be persistent in soil for decades in certain environments and regions regardless.
Malicious use
Many antagonists and villains within XNDUIW have used anthrax as a weapon to cause death and destruction, considering that certain authoritarian regimes have used it for state-sponsored genocidal acts, to bioterrorism programs committed by terrorists and high-level criminals as well. It has been used by criminals or murderers to ensure that their victims are knocked out or dead, as the spores can be dormant in the soil for a prolonged period of time, and it can be undetectable in the environment.
Possession of anthrax constitutes a grave criminal offense and a severe felony, which can result in lengthy prison terms, possibly up to either life imprisonment or even the death penalty if convicted of such actions. In addition, it is a prohibited weapon under international humanitarian law, as it is also a criminal offense to send anthrax through the mail, even if it was a prank or a hoax.
Prevention
Precautions are provided to avoid contact with skin, or any fluids exuded from a deceased person's body who is contaminated with anthrax, considering that protective, impermeable clothing along with rubber gloves and boots are generally used to handle such materials, considering that this is not a surprise, especially when it comes with major forms of whatever was done.
Vaccines
There is a vaccine for anthrax, though it is extremely rare to encounter in the general public, as the vaccine isn't available for civilians, every day people, as it is only intended to be administered to soldiers, laboratory technicians, agricultural workers, high-level politicians, emergency first responders, and industrial workers as well. In fact, because the vaccine's use is extremely restricted, you will never see it used by the player within the XNDUIW lore, and instead you will get the vaccine by an authorized non-player character with the required qualifications.