Patient zero is generally taken to mean the first case in a disease outbreak – but the term is often applied in different ways. When it comes to zoonotic diseases (ones that jump from animals to humans, like SARS-CoV-2), patient zero might refer to the first-ever human case – the point at which the virus spills over from an animal to a human. For the general public, however, patient zero is often used to refer to the first case in a particular region, or the first case that's come to the ...

Patient zero is generally taken to mean the first case in a disease outbreak – but the term is often applied in different ways. When it comes to zoonotic diseases (ones that jump from animals to humans, like SARS-CoV-2), patient zero might refer to the first-ever human case – the point at which the virus spills over from an animal to a human. For the general public, however, patient zero is often used to refer to the first case in a particular region, or the first case that's come to the attention of health authorities. However, these are not always the same thing. Sometimes the first case that's notified to us is not the first case in an outbreak. Similarly, just because someone is identified as the first case doesn't mean they spread the disease to anyone else, or behaved irresponsibly – with something like coronavirus, they may not even know they're sick.

This is part of the reason why patient zero is not a term epidemiologists or public health experts tend to use - it's not specific enough. They prefer the term index case to refer to the first person officials became aware of in an outbreak (which gives them a clue something's going on), and primary case to refer to the person who introduces a disease into a new population - a community, country or the world. Sometimes, the primary case and the index case will be the same person, but not always. For many outbreaks - such as HIV/AIDS, and possibly COVID-19 – we will never know the primary case.

While the use of the term patient zero can be fraught, tracing outbreaks back to their beginnings remains important in public health. In the early days of an outbreak, it's still possible to catch embers of disease before they become full-blown fires. "You can actually stamp them out, by identifying every case, tracking every contact, quarantining them, making sure there's no further spread," Professor Raina Macintyre, head of biosecurity at UNSW's Kirby Institute says. But even after those critical first days or weeks, tracing cases back to patient zero can still give both health experts and relevant authorities for insights into how disease spreads and understands the role that health services and adequate sanitation systems play in controlling the spread of the disease. That's the purpose of trying to understand an index case or a first case – to establish the opportunity to learn from the breakout and try to make sure it doesn't happen again.

According to the passage which statement is true about SARS-CoV-2?