There are many kinds of cancers, STDs and more that don't show symptoms.

If you have cancer, you definitely have symptoms. Because cancer is malfunction, so something works wrong. And that difference from normal body function is named "symptom".

A person can even have HIV and not know it for years.

If there is no symptoms, there are no illness. You can have any virus but if there is nothing changed in your body that means you are not ill. Presense of virus in a body does not mean illness. Most human coronaviruses does not cause any illness. If you once got chicken-pox as a child, you can't become ill from chicken-pox virus at all. Right now you have at least few dozens different kinds of viruses in your body that does not (and mostly can't) cause any illness. They are integral part of your natural microbiome., Moreover, if you completely get rid of some of them (bacteriophages, f.e.), you will become ill.

There is thing named natural immunity - normal body function to neutralize known pathogens if they appear in a body before they do any harm, that don't allow pathogen make you ill. Some people could have immunity to HIV, or just be unvulnerable for it due to specific DNA. And It is without discussing the fact that there is no any scientific proof that HIV is a cause of any illness, including AIDS.

If body does not know how to neutralize pathogen, pathogen can have time do a harm to a body and body will show symptoms, directly from damage caused by pathogen or from low-level damage repairing process (inflammation, f.e.). And in that case and only in that case that would be illness.

getting tested regularly for asymptomatic illnesses

There are can't be asymptomatic illnesses/diseases at all. Illness/disease absolutely means symptoms just by definition. Illness/disease is a presence of symptoms. illness/disease is defined as disorder of structure or function of body, it means that body is not working properly. And that disorder or improper working is named "symptom". If you have no symptoms - there are no disorder or malfunction, so you can't be ill.

"asymptomatic disease" is pure oxymoron, invented by swindlers from WHO only year and half ago to blow up coronahoax figures from nothing.

There are many kinds of cancers, STDs and more that don't show symptoms.

If you have cancer, you definitely have symptoms. Because cancer is malfunction, so something works wrong. And that difference from normal body function is named "symptom".

A person can even have HIV and not know it for years.

If there is no symptoms, there are no illness. You can have any virus but if there is nothing changed in your body that means you are not ill. Presense of virus in a body does not mean illness. Most human coronaviruses does not cause any illness. If you once got chicken-pox as a child, you can't become ill from chicken-pox virus at all. Right now you have at least few dozens different kinds of viruses in your body that does not (and mostly can't) cause any illness. They are integral part of your natural microbiome., Moreover, if you completely get rid of some of them (bacteriophages, f.e.), you will become ill.

There is thing named natural immunity - normal body function to neutralize known pathogens if they appear in a body before they do any harm, that don't allow pathogen make you ill. Some people could have immunity to HIV, or just be unvulnerable for it due to specific DNA. And It is without discussing the fact that there is no any scientific proof that HIV is a cause of any illness, including AIDS.

If body does not know how to neutralize pathogen, pathogen can have time do a harm to a body and body will show symptoms, directly from damage caused by pathogen or from low-level damage repairing process (inflammation, f.e.). And in that case and only in that case that would be illness.

getting tested regularly for asymptomatic illnesses

There are can't be asymptomatic illnesses/diseases at all. Illness/disease absolutely means symptoms just by definition. illness/disease is defined as disorder of structure or function of body, it means that body is not working properly. And that disorder or improper working is named "symptom". If you have no symptoms - there are no disorder or malfunction, so you can't be ill.

"asymptomatic disease" is pure oxymoron, invented by swindlers from WHO only year and half ago to blow up coronahoax figures from nothing.

There are many kinds of cancers, STDs and more that don't show symptoms.

If you have cancer, you definitely have symptoms. Because cancer is malfunction, so something works wrong. And that difference from normal body function is named "symptom".

A person can even have HIV and not know it for years.

If there is no symptoms, there are no illness. You can have any virus but if there is nothing changed in your body that means you are not ill. Presense of virus in a body does not mean illness. Most human coronaviruses does not cause any illness. If you once got chicken-pox as a child, you can't become ill from chicken-pox virus at all. Right now you have at least few dozens different kinds of viruses in your body that does not (and mostly can't) cause any illness. They are integral part of your natural microbiome., Moreover, if you completely get rid of some of them (bacteriophages, f.e.), you will become ill.

There is thing named natural immunity - normal body function to neutralize known pathogens if they appear in a body before they do any harm, that don't allow pathogen make you ill. Some people could have immunity to HIV, or just be unvulnerable for it due to specific DNA. And It is without discussing the fact that there is no any scientific proof that HIV is a cause of any illness, including AIDS.

If body does not know how to neutralize pathogen, pathogen can have time do a harm to a body and body will show symptoms, directly from damage caused by pathogen or from low-level damage repairing process. And in that case and only in that case that would be illness.

getting tested regularly for asymptomatic illnesses

There are can't be asymptomatic illnesses/diseases at all. Illness/disease absolutely means symptoms just by definition. illness/disease is defined as disorder of structure or function of body, it means that body is not working properly. And that disorder or improper working is named "symptom". If you have no symptoms - there are no disorder or malfunction, so you can't be ill.

"asymptomatic disease" is pure oxymoron, invented by swindlers from WHO only year and half ago to blow up coronahoax figures from nothing.