HAS THE COVID-19 PANDEMIC AFFECTED VACCINE DEVELOPMENT NOW AND IN THE FUTURE? By Harriet Virology has never been reported on as frequently or as in depth as it had been since the start of the SARS-CoV-2 pandemic. There also seems to have been a greater rate of development of vaccines and technology surrounding vaccination during and due to the pandemic. The truth is, before the rise of SARS-CoV-2, we already knew quite a lot about coronavirus, how they are structured and how to mitigate them because of the previous SARS and MERS epidemics. This means that as soon as the emerging virus was identified to be a coronavirus, no one was particularly surprised as there had been two epidemics of coronavirus in the past twenty years. Over the course of the pandemic, two novel forms of vaccines have been approved to add to the three previous forms of vaccination. There was also a new parallel development scheme created whereby the vaccine was being produced as testing was being done. The previous forms of vaccination are: INACTIVATED VACCINE This is when a killed version of the virus by chemical treatment is used as inactivated vaccines don’t have ability to interact with cells or produce proteins which therefore does not causethe patient’s body any harm. However, if the immune system of the individual is exposed to enough units of the killed pathogen, an immune response can be induced. This, however, will be weak and will need ‘booster’ vaccinations to cause a sufficiently protective immune response for when the wild virus enters the individual’s body. Examples of this type of vaccine are the polio vaccination as well as some more topical COVID-19 vaccines such as Covaxin, produced by an Indian company, Bharat Biotech. It has an efficacy of 78% against symptomatic patients and a 64% efficacy against asymptomatic patients. This type of vaccination hadn’t been changed or developed over the course of the pandemic. LIVE ATTENUATED VACCINE This is the original form of vaccination. This form was used 300 years ago by Edward Jennerto vaccinate the public against smallpox. The vaccine contains a weakened version of the pathogen which, once injected, produces weakened versions of the pathogenic proteins, training the immune system for when the virus enters the body wild. This causes a longer lasting immune defence than the inactivated vaccines, thus needing few follow up vaccinations. However, live attenuated vaccines can cause mild disease, all be it weakened. Protein is being produced thus immunodeficient patients may need to consult their General Practitioner before receiving the vaccine as it can cause more severe and longer lasting damage. An example is the MMR vaccine which is administered to babies. This type of vaccine has been totally unaffected by the pandemic as there has been no live attenuated COVID-19 vaccinations, thus causing no development or change to the vaccine or how it is produced. SUBUNIT/RECOMBINANT/PROTEIN SUBUNIT VACCINES These vaccines can, but don’t always, contain a chemical called an adjuvant. This stimulates the immune system causing a more effective immune response. An example is AS04 in an HPV vaccine called Cervarix. It is made up of monophosphoryl lipid A and Aluminium salt. Subunit vaccines take the genetic information of one appropriate protein, usually the spikeprotein, and produce it using an alternative method using molecular biology techniques. This is then injected into the body. As there are only fragments of the pathogen entering the body, not the whole virus, the fragments are rendered harmless so the immune response is still triggered, thus still developing an immune response against the pathogen. This also makes the vaccine very safe, allowing immunodeficient patients to have a vaccine without any problems. Examples include the vaccine against hepatitis B. There are many COVID-19 vaccines using this technique, the most popular being Nuvaxovid (approved in 36 countries including the United Kingdom. Vaccine structure or development has not been affected by the COVID-19 pandemic, although many types of subunit vaccinations have been made for sars-cov-2, very few have been approved or been effective.
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THE CHRONICLE
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