100% truth.

Cannon firing explosive shells, or hand-held explosives, are used to trigger avalanches deliberately to reduce risk to people moving in mountainous areas with heavy snow.

You didn't ask how loud a noise. The answer is "very loud" - explosions. Yelling loudly won't do it.

Correct. Not least because immune activity killing off nerve and brain cells is a serious problem because they regrow slowly or never, so the compromise is that the immune system does not touch irreplaceable cells and aims to kill viruses and bacteria before they can reach those cells.

That's true, and very unusual among viruses.

You can also be pre-emptively vaccinated for it, and then it works well too.

I haven't kept up with the exact differences, but I will say that rabies is 100% deadly and herpes is 0% deadly, which may affect the amount of effort put into this.

Rabies also does not hide out in nerves. It travels along nerves to the brain, but it doesn't hide there in a mostly-inactive state for a long time. It vigorously infects nerves and travels along them, which makes it more vulnerable to immune cells and also triggers more response from immune cells.

HIV is like a rootkit on the software of your immune system: it destroys the very cells that would be sent to destroy it. That's why it's so hard to vaccinate against. Fortunately, we have very effective treatments to suppress it and we can, if we deploy these widely enough, expect to suppress it out of transmission in the foreseeable future. HIV isn't very easy to transmit so if you suppress it in the people who have it, it should die out when the oldest person with HIV dies of other causes, after spending their life with suppressed HIV.

Herpes is a sneaky bastard that hides out in nerve cells, out of the way of the immune system. The immune system can deal with it if it can find it, so that's why it hides.

Note that the work to be able to create a Covid vaccine has been in progress for decades. BioNTech (the actual inventors of the "Pfizer Covid vaccine") was founded 15 years ago and the more fundamental research on mRNA vaccines was done before the company was founded.

A huge amount of this understanding of viruses comes from the ability to sequence genomes. This is almost magical - it really is science fiction come to life. It's as magical as the "Star Trek communicator" becoming "cellphone in your pocket, works worldwide". The Human Genome Project required rooms full of thousands of expensive machines working for several years to sequence one genome. Today, you can do a full sequence of a human-size genome in less than a day (current record: 5 hours 22 minutes!). You can grab a random virus or bacterium and sequence it overnight, just to see what's interesting in its genome. If you find another one tomorrow, you can compare them over the weekend. This is a huge change for all life sciences.

It was sheer luck that mRNA technology was almost advanced enough to make vaccines for coronaviruses when SARS-CoV-2 (the virus that causes COVID-19) showed up. A lot of researchers worked a lot of overtime to turn "almost" into "actual" in an amazingly short time.

We also have a lot of experience making vaccines to viruses that the immune system can handle when suitably primed (i.e. NOT retroviruses like HIV, but most others) in other ways - using similar virus strains, culturing viruses and inactivating them, weakened live viruses, and so on. These methods had been used to produce vaccines for the SARS virus (the vaccines were not widely tested because by the time they were ready, there were too few cases to test and no need for them). The same techniques were also used to produce SARS-CoV-2 vaccines.

We can expect a lot more vaccines for diseases previously considered impossible to vaccinate against, using mRNA technology.

Aside from mRNA tech, research continues on other diseases. RSV (Respiratory syncitial virus) is a serious disease for infants, but attempts to make vaccines were disastrous in the past and the reason why the first attempts failed has only recently been understood after 30 years of work. This work doesn't even use mRNA knowledge, it's completely separate innovation.

Virology and immunology are both extremely complex topics which we have, across the world, not nearly mastered. We do not understand either, not even nearly, so the rate of advance of knowledge is rapid in both. When they intersect, they are both even more complicated. You have to see the current state of vaccines as a work in progress, where some problems have been solved and others have not, depending on random chance and whatever seems most important at the time.

I'm nearly 50 years old. In my lifetime, we have gone from commonplace vaccines for only a few things - polio, etc - to vaccines for a whole array of nasty diseases (measles, mumps, rubella, diptheria, typhoid, tetanus, pertussis, pneumococcus, influenza (moving target, alas), etc).

I expect in 50 more years, we'll have zapped most of them.

Yes, one should think of it as "an-hemia", lack of heme(oglobin), not just a lack of iron atoms. Which could be due to lack of iron (or other things) to make heme, or lack of ability to make heme despite having the necessary essential minerals, or sudden loss of heme.

"Cancer" is a large set of diseases, some of which are caused partly or entirely by inherited genes and some of which are not. Few cancers are caused entirely by inherited characteristics. Instead, some genes make it more likely that a person will develop a particular form of cancer but there is usually some environmental condition that also causes actual cancer to develop.

This can, for example, be that a person has a gene that makes some cells more likely to divide and multiply out of control than usual, but their general immune system cancer-suppression works OK and suppresses it until they have a degraded immune system for another reason. Then they develop cancer.

Or a person may be more prone to cancer, and are then exposed to a further environmental carcinogen, and they develop cancer. Another person with the same predisposition who is not exposed, may not develop cancer.

Even without any predisposition towards being more likely to develop cancers (which is very unlikely - no-one has a perfect genome), exposure to a strong carcinogen may still cause you to develop cancer.

There are also many random factors, such as cosmic rays (literally), that can cause cancer to begin in some part of your body. It's not very likely, but it's definitely possible.

If you don't have any known predisposition towards cancer, then it's probably not something to worry about.

Avoid risk factors like smoking, get your colon checked when you're 50, check your breasts and/or testicles for lumps on a regular basis, and get any odd lumps or persistent unexplained pains, changes in appetite or weight, etc, checked out, but don't go around worrying every day.

Have you asked your GP, or even the doctor who did the surgery, about this?

There may be reasons why the port-a-cath site has more inflammation, including the drugs administered through it (especially if you had chemotherapy via it).