My Vaccine Experience

So, as planned, I had my first injection of the Astra-Zeneca COVID vaccine on March 23rd and it couldn’t have gone more smoothly. I thought I’d post about my experience to reassure people about the vaccine in general and AZ in particular. And to let people in the UK know what to expect when you attend a mass vaccination centre.

The first thing you should be aware of is that you won’t be allowed to enter the building until five minutes before your appointment. Not a problem if you are driving and can wait in the car, but worth bearing in mind if you are going on foot. When you go in you will be asked to sanitise your hands and wear a face mask; if you are exempt, you will be given a plastic visor to wear.

A receptionist will check your details and give you your NHS number if you don’t know it. You will then be directed where to go next. The mass vaccination centre I attended was very much a multi agency affair; as well as NHS staff there were personnel from the Fire Service, Army, RAF and St John Ambulance.

When it’s your turn you will be called forward to sit at a table where you will be asked a series of questions to determine your eligibility and suitability for the vaccine. This is a safety check where they will ask about things like allergies, underlying medical conditions and whether you are taking certain medications. When this is done, they will tell you which vaccine you are getting and ask for your verbal consent. They will also give you a detailed information sheet and will answer any questions you have.

Once that is done, the person processing you will call a medic over who will give you the actual injection. Don’t be surprised if this is a member of the Armed Forces. I was processed by a RAF medic and given the injection by an Army medic. You can be reassured that they will have had the same level of training as NHS staff.

After the injection you will be given a card which you need to bring to your next appointment. For me, getting through the next 12 weeks without losing it, or forgetting where I’ve stashed it so I won’t lose it, is possibly the most stressful part of the process! You also get a sticker but sadly no lollipop – that’s NHS cutbacks for you!

If you have driven to the vaccination centre, you will then be asked to wait in a waiting area for 15 minutes. The waiting area is socially distanced and is monitored by someone trained to spot any signs of anaphylaxis. Make sure you take a book or tablet or something – I didn’t and had to resort to reading the BBC news on my very small iPhone SE!

So, what about side-effects? There has been a lot of adverse publicity about the AZ vaccine and particularly its safety in younger age groups. Well, I am 48 and had absolutely no concerns about having the AZ vaccine. About 3 hours after the vaccine I started feeling very tired and generally a bit off-colour. I also developed a strong metallic taste in my mouth. Since this is a COVID symptom and is not yet on the official list of AZ side-effects I had to leave work, get a PCR and self-isolate until the result came in.

The PCR result was negative and the symptoms disappeared almost exactly 24-hours after they first appeared. I had a sore arm for a few days but no worse than the flu vaccine. And nothing compared with the pneumococcus vaccine – anyone reading this who’s had it will know exactly what I mean!

I mentioned that altered taste is not yet officially a side-effect of the AZ vaccine, although I know a number of other people who experienced it. This is why it’s really important that people use the Medicines and Healthcare products Regulatory Agency’s Yellow Card system to report any side effects. The Yellow Card system is used to collect data on all medications, but they have a dedicated site for COVID medications and vaccines. You can access it using the link at the end of this post. Note, this only applies to the UK but other agencies such as the FDA in the US and the EMA in Europe have similar reporting systems.

All in all, other than the lack of lollipops, my experience of getting the first jab was entirely positive. I look forward to getting my second one, not least because then I can stop worrying about where I put that darned card…

Link to yellow card:

https://coronavirus-yellowcard.mhra.gov.uk/

What is mRNA, and how does it work?

I am very, very happy and excited today! The reason? I have a date booked for my COVID vaccine. 23rd of March is the day (coincidentally, the anniversary of the first UK lockdown), and it can’t come soon enough for me. The speed at which the various COVID vaccines have been developed, tested and approved for clinical use is impressive and means that we should, finally, have the end of this pandemic in sight. Unfortunately though, the anti-vaxxers are coming out of the woodwork in droves, and there are all sorts of myths and misinformation being pedalled on social media.

This is the first in a series of posts I am planning about the COVID vaccines. Many of the vaccines, including Pfizer and Astra Zeneca, are mRNA vaccines. So, I am going to start with the basics: what mRNA is and how it works.

mRNA is one of a group of biological molecules called the nucleic acids. These are DNA, and various types of RNA. Nucleic acids consist of molecules called nucleotides, joined together in long chains. Each nuclotide consists of a sugar, a phosphate group and a nitrogenous base. The sugar and phosphate make up the backbone of the chain, and the nitrogenous bases make up the genetic code.

A DNA molecule consists of two single strands, which combine to form the familiar double-helix.

DNA stands for deoxyribonucleic acid. It is a stable, information storage molecule that contains the ‘instructions’ for making proteins. In humans, all the instructions (genes) for every protein the body needs to make are stored on 46 molecules of DNA, called chromosomes. These make up the genome, and are found in the nucleus of every cell. DNA nucleotides consist of a phosphate group, the sugar deoxyribose, and one of four bases: adenine (A), thymine (T), guanine (G) and cytosine (C).

mRNA is single-stranded and much shorter than DNA.

DNA never leaves the nucleus of a cell. For one thing, it’s too big and cumbersome. For another, it needs to be protected against damages. So, when a cell needs to make a particular protein, the gene for that protein is copied in the form of messenger RNA or mRNA. Ribonucleic acid (RNA) differs from DNA because it is a short-term molecule used for the transfer and processing of genetic information. There are many types of RNA, of which mRNA is just one. RNA nucleotides consist of a phosphate group and the sugar ribose. Three of the nitrogenous bases are the same as those in DNA: A, G and C. However, thymine (T) is replaced with uracil (U).

When a cell needs to make a particular protein, an enzyme called RNA polymerase copies the gene in the form of a molecule of mRNA; this is called transcription. The mRNA leaves the nucleus of the cell and enters the cytoplasm, where it binds to a structure called a ribosome; the ribosome then assembles the protein. This is called translation.

A virus like COVID-19 cannot manufacture its own proteins. Instead, it must infect a cell and take over its organelles.

Viruses like COVID-19 cannot carry out transcription and translation, since they do not have ribosomes and various other things that are needed. Viruses carry their genetic material in the form of DNA or RNA – RNA in the case of COVID-19. When COVID-19 infects a cell, the virus capsule breaks open, releasing the RNA into the cell’s cytoplasm. Ribosomes in the cell will bind to the viral RNA in the same way they bind to mRNA, and will manufacture the necessary proteins for producing new viruses.

Lateral flow vs PCR: how do they work?

Lateral Flow Test

There has been some controversy in England this week surrounding the mass testing of pupils for COVID-19 as they return to school. The problem is that the government seems to be contradicting itself regarding the relative reliabilities of the lateral flow test (LFT) and the polymerase chain reaction test (PCR). If a student has a positive LFT from a test done at home, and they subsequently have a negative PCR test, they can return to school. If a student has a positive LFT from a test done at school, then they must self-isolate for ten days even if a subsequent PCR is negative. In this post I am going to explain how the two tests work, and why a positive LFT is always followed up by PCR.

When a new LFT for detecting small amounts of EPO was developed, Lance Armstrong decided to confess.

LFT or, to give it its full title, lateral flow immunoassay, is not new; in fact, it’s been around for years. LFT is a quick, cheap and simple method used to detect specific analytes or biomarkers. Prior to COVID, the most common use of LFT was in pregnancy testing. Lateral flow testing is also used in drug testing, for example in testing athletes for performance enhancing drugs such as EPO. In fact, it was the development of LFTs that could test for EPO that led Lance Armstrong to confess to having used it in his 7 Tour de France wins; he knew that when stored urine samples were tested using the new method, the game would be up.

LFTs are used to check for substances or biomarkers in bodily fluids or swabs. Urine is commonly used in drug testing, while swabs are used to test for pathogens. LFTs use two lines: one is a control line, which confirms that the test is working; the other is the test line. The lines are made up of labels; these are nanoparticles of substances which will bind to the substance being detected and cause a visible line to appear. Labels include nano-beads of coloured polystyrene or latex (a nano-bead is a bead that is around one millionth of a millimetre in diameter!).

This LFT is positive for COVID. You can clearly see the control and test lines.

So, how does it work for COVID? When you have done your throat and nasal swab, you or whoever is carrying out the test will swirl the swab tip in a small amount of extraction buffer. This is a solution which will break down any virus particles, releasing their RNA; it also maintains the pH (acidity) at a constant level, because changes would affect the result. When you do your test, the control line will appear within a couple of minutes to show that the test is working. If the test is positive, the test line will appear within about 30 minutes.

Polymerase Chain Reaction

The enzyme used in PCR was isolated from bacteria that live around underwater thermal vents. This means that it can withstand the high temperatures used in PCR.

PCR is basically a process which uses an enzyme called polymerase to make multiple copies of DNA or RNA; this is called amplification. This means that PCR can detect extremely small amounts of either substance. One of the most widespread uses of PCR is in forensic science where it is used to amplify minute amounts of DNA to a level where it can be analysed.

In forensics, PCR is particularly useful in solving cold cases. Famously, PCR was used to identify the remains of Tsar Nicholas II and his family from very small samples of mitochondrial DNA.

PCR was used to identify the remains of the Romanovs.

The major advantage of PCR in testing for COVID is that it can detect the virus at much lower levels than LFT. This means that it is particularly useful in testing close contacts, who may have the virus but whose viral load is too small to cause symptoms or a positive LFT. Analysis of the swab is also carried out entirely by professionals working in sterile laboratories, so the potential for human error or contamination is very low.

PCR has several disadvantages. It requires specialist equipment so must be done in a lab, making it more expensive. It also takes much longer. Amplification of the virus’ RNA using PCR requires multiple cycles of heating and cooling, taking several hours. Some people argue that because PCR is a multi-stage process, there is actually more potential for human error than with LFT; personally, I do not agree with this. PCR has been used for many years in forensic and diagnostic applications, and has consistently been found to be reliable.

So, should students who have had a positive LFT in school but a subsequent negative PCR be allowed back to school? Having considered all the scientific evidence, my opinion both as a scientist and as a teacher is yes they should. The argument is that LFTs in school are administered by staff, so they are more reliable than those done at home. That may be the case, but it certainly does not mean that they are more reliable than PCR, which is widely regarded as the ‘gold standard’ within the scientific and medical communities. To me, this is yet another example of the lack of medical and scientific understanding at the highest levels of government, but don’t get me started on that one!