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How Vaccines Function

Covid vaccine side effects are caused by your immune system’s inflammato­ry reaction to foreign molecules, writes Ian Madigan


Vaccine should be in with a shot for word of the year in 2021, as countries worldwide deploy Covid vaccinatio­n programmes to suppress the global pandemic. The EU has approved four vaccines for use among member states, while four other vaccines are in the pipeline for authorised deployment. It is estimated that another 80 Covid vaccines are in clinical developmen­t.

So what is a vaccine? Essentiall­y, it is a piece of informatio­n sent to your immune system to help it identify a disease before you contract it. Covid vaccines present your immune system with instructio­ns for making a piece of the Covid-19 virus structure. Your body makes it, then recognises that it doesn’t belong in your cells and attacks it. It does so by producing proteins called antibodies that latch onto the virus and incapacita­te it.

These antibodies stay in your system and will recognise and eradicate Covid if you are infected with the virus. Different vaccine types will complete this process in different ways, but the end goal is the same. Your immune system will recognise the Covid-19 virus thanks to the ‘heads-up’ provided by the vaccine, and will produce antibodies to destroy it if it ever infects your body.

The three main Covid vaccines currently being used in Ireland were developed by Pfizer-BioNTech, Oxford-AstraZenec­a and Moderna. Both the Moderna and Pfizer vaccines use mRNA technology, which delivers genetic instructio­ns to your cells on how to create a piece of the Covid-19 virus. This genetic ‘instructio­n sheet’ is broken down by your body afterwards and it never gets encoded into your DNA, as some vaccine sceptics wrongly claim.

The AstraZenec­a vaccine is a viral vector vaccine, meaning that it delivers the genetic informatio­n to make a piece of the Covid-19 virus via another, weakened virus – in this case a strain of cold virus taken from a chimpanzee. You don’t become infected with this cold or with Covid-19 through the AstraZenec­a vaccine, and it also doesn’t become part of your DNA. None of the other vaccines being used in Ireland give you Covid-19 either – they just give your body a means of identifyin­g the virus if you ever become infected, so that your immune system can stop it from taking hold.

The three vaccines require two doses several weeks apart, because the first dose triggers an immune response that is too weak to be optimally effective. After two doses, Moderna said that 94% of people gain Covid immunity, while Pfizer claims its efficacy at 95%. AstraZenec­a’s stated efficacy is between 76% and 82%.

Side effects are relatively common from Covid vaccines, including headaches, a high temperatur­e, runny nose and sore muscles. These are caused by your immune system’s inflammato­ry reaction to foreign molecules in the body. It is not the case that strong side effects mean you have a better or more active immune system. It’s not known how long Covid vaccine immunity lasts, though it’s not forever, with the mRNA vaccines only promising at least six months’ immunity.

Thanks to vaccines, viruses such as polio and smallpox have been eliminated from most of the world, while many other viruses are tightly contained. The Covid vaccines are safe, so when you get the opportunit­y to be vaccinated against Covid, take it.

‘Vaccines give your body a means of identifyin­g the Covid-19 virus’

 ??  ?? Covid vaccinatio­n looks like being a perennial shot in the arm
Covid vaccinatio­n looks like being a perennial shot in the arm

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