A thread on vaccines:
Most of us have been vaccinated quite a few times in our lives. As a young child I remember getting the Polio vaccine at “the dispensary” on a cube of sugar.

That was a treat I hadn’t expected, but even though, at that time, I thought that the sugar lump was the best thing about it, I now realise that the life-long immunity that it gave against Polio, was the real treat.

Towards the end of primary school, I also received the TB vaccine (BCG), or what I guess was a top-up vaccination, in what was a slightly less pleasant experience, as this time a needle was involved.

Unpleasant it may have been, but nothing compared to Ireland 100 years ago, when more than 10 people died each day from TB.

I would also have had vaccines for Diphtheria, Whooping Cough and Tetanus, though I only remember the Tetanus shots, as I have had a few of these down the years.

As I got the measles and German measles (Rubella) as a child, I wasn’t vaccinated for these once the vaccines became available, but I do get a flu vaccination each year, as I learned a hard lesson about 20 years ago, on how severe the flu can be.

Up until recently, vaccines contained either weakened living viruses or purified signature proteins of the virus. Our bodies would detect the injected material, recognize it as a potential invader, and create antibodies to eliminate it.

This would be by directly destroying the invaders or by blocking them from infecting cells. After receiving a vaccine, a small number of these antibody-producing immune cells usually remain in the body as memory cells, providing immunity to future infections of the same virus.

Because memory cells and antibodies are already present, next time the body encounters the same microbe, the immune response is much faster and can stop the infection from taking hold.

Interestingly, the mechanism of future immunity is exactly the same whether you get the virus infection for real, or whether you take a vaccine.
Which brings me to the subject in my mind, which is RNA vaccines (also known as mRNA, or messenger Ribonucleic Acid vaccines).

The difference in RNA vaccines is that, rather than having the viral protein injected, a person receives genetic material – mRNA – that encodes the viral protein. When these genetic instructions are injected into the upper arm, the muscle cells translate them to make the viral...

protein directly in the body. We are injecting a messenger to tell our muscle to make a viral protein, which our body then deals with like any foreign protein – by making antibodies to eliminate it. Clever or what?

This approach mimics what would happen in our bodies if a real virus infected us, but the vaccine or messenger codes only for the critical fragment of the viral protein. This gives the immune system a preview of what the real virus looks like without causing disease.

This preview stimulates the immune system to make antibodies that will eliminate the real virus if the individual is ever infected.

After an mRNA injection, the messenger guides the protein production inside the muscle cells, which reaches peak levels for 24 to 48 hours and then declines in the following few days.

While the synthetic mRNA is genetic material, it cannot be transmitted to the next generation, and is short-lived in the muscle.
Traditional vaccine development, although well studied, is very time-consuming and cannot respond instantaneously against novel pandemics such as COV19

People are rightly amazed at how quickly these mRNA vaccines were developed. Indeed, it was only in 2005 that researchers figured out how to stabilize mRNA and package it into small particles to deliver it as a vaccine.

So if Covid19 had appeared 20 years ago, we would probably be waiting at least a few years for a vaccine.
Luckily mRNA vaccines can bypass some stages of developing traditional vaccines such as producing noninfectious viruses, or producing viral proteins at medically demanding...

...levels of purity. That is because, instead of making these elements at large scale, (culturing them in hen’s eggs) the human body uses the instructions to manufacture viral proteins itself, removing these steps in the production process.

In addition, mRNA is manufactured by chemical rather than biological synthesis (hen’s eggs again), so it is much quicker than conventional vaccines to be scaled up and mass-produced. In fact, within days of the genetic code of the Covid19 virus becoming available...

...in early January 2020 (which was only 10 days after the outbreak was reported in China) the mRNA code for a candidate vaccine was already known.

Of course, some people may be nervous about taking a vaccine, which has originally only been tested on about 40,000 people. Naturally the regulatory agencies will continue to monitor for side-effects, such as unintended immune reactions...

as is the case for all vaccines, and the more people receive the vaccine, the more precise scientists can be about their confidence in the safety of the vaccines.

Having confidence in the safety of a vaccine is a key consideration encouraging uptake, and thus far the more common side effects are tiredness, fever, headaches, muscle and joint pain. However, these are short-lived and not uncommon for vaccines.

I hope this article makes readers more comfortable about RNA vaccines, and wish to thank colleagues in University of Limerick ( @ul) for their helpful pointers when writing it.
And yes, obviously I will be very eager to take the vaccine when my turn comes.