Types of COVID-19 Vaccines. How is vector different from mRNA vaccine? [WE EXPLAIN]

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We can now vaccinate ourselves against COVID-19 with four preparations. We can choose from two mRNA vaccines – one produced by Pfizer / BioNTech, the other by Moderna, and two vector vaccines – AstraZeneki and Johnson & Johnson. How do genetic and vector vaccines differ? What happens in the body after taking them? We explain.

1. Four COVID-19 vaccines are currently available in Poland. Two mRNA vaccines (Pfizer / BioNTech and Moderna) and two vector vaccines (AstraZeneca and Johnson & Johnson)
2. The preparations differ not only in the production technology, but also in e.g. storage method
3. Deputy Minister of Health Waldemar Kraska reminds that all vaccines available on our market are safe and effective. «It doesn’t matter which vaccine we get vaccinated with. It is important that this vaccination takes place »
4. More current information can be found on the Onet homepage.

COVID-19 vaccines in Poland

Vaccinations against COVID-19 have been ongoing in Poland from December 27, 2020. Since then, more than 44 percent have taken at least one dose. Poles, the full vaccination cycle is completed by over 34 percent.

We all remember that the first vaccine against COVID-19 approved for use in the European Union, and the first one used in Poland, was a preparation developed by Pfizer / BioNTech. Since then, three more vaccines have been marketed in the EU – Moderny, AstraZeneca and a single-dose preparation by Johnson & Johnson. They are also used in Poland. It is also worth mentioning about the vaccines produced by CureVac and Sanofi / GSK, which have not yet been approved by the European Medicines Agency (EMA).

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It is worth knowing that the COVID-19 vaccines that we can use differ in terms of production technology, storage method and effectiveness. Here’s everything you need to know about them.

Genetic vaccines – Pfizer, Moderna, CureVac

The two coronavirus vaccines, Pfizer and Moderna, which have already been approved for use, and the CureVac vaccine, which is awaiting approval, are next-generation mRNA vaccines.

In genetic vaccines, one or more genes of the virus are used to trigger an immune response in the body. It can be said that mRNA vaccines against COVID-19 deliver instructions to our cells – in the form of an mRNA molecule. It tells how cells are to produce the S protein – the so-called the spike protein by which the virus enters the host’s mucosa and causes disease.

This instruction reaches a very limited number of cells, especially muscle cells. Thanks to this information, cells start to produce this S protein, then it is recognized by the body as “foreign”, and this results in the production of appropriate antibodies. In this way, the immune system trains in a way to recognize the aforementioned S.

It is worth remembering that, unlike traditional vaccines, preparations based on mRNA do not contain inactivated (killed) viruses or even parts of them. Another important thing, after the production of the S protein, the mRNA molecule degrades, does not replicate and does not disseminate in the body.

Over and over again, concerns or claims may be heard that mRNA vaccines genetically modify the body’s cells. This issue was explained a few weeks ago by prof. Joanna Zajkowska from the Department of Infectious Diseases and Neuroinfection at the University Teaching Hospital in Białystok: mRNA does not genetically modify the cell, there is no such possibility, because it does not work in the cell nucleus, it is generally unstable, it cannot penetrate our genome – emphasized the expert.

1. More on this in the article: After an mRNA vaccine, the risk of having COVID-19 severely increased? It’s a myth

Although the vaccines developed by Pfizer, Moderna and CureVac are based on the same technology, there are differences between the two. First, effectiveness. From the available research results, we learn that Pfizer’s COVID-19 vaccine provides 95 percent of the total. effectiveness in preventing COVID-19, a vaccine developed by Moderna – over 94% Curevac recently announced that its coronavirus vaccine had an initial success rate of 47%.

When it comes to the effectiveness of mRNA vaccines in preventing hospitalization – according to the data published in the medical journal “The Lancet” – in the case of mRNA vaccines it is about 96%.

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Another difference is the way of storage. Vaccinated against COVID-19, Pfizer remains effective for six months if stored at -90 to -60 degrees C. Before use, it can be stored for up to five days at 2 to 8 degrees C and for a maximum of two hours. at temperatures up to 30 degrees C.

The Moderna vaccine does not need such low storage temperatures. It can be stored and transported at a temperature of -25 to 15 degrees C and stored up to 30 days at 28 degrees C.

CureVac has the least of the three storage requirements listed. It remains stable for three months at a temperature of +5 degrees C, and it is usable for 24 hours at room temperature.

All three preparations require two doses for full immunity.

Vector vaccines – AstraZeneca and Johnson & Johnson

Vector vaccines rely on the use of fragments of other viruses (which act as vectors) to elicit an immune response against a specific virus – in this case SARS-CoV-2. The virus provides the body’s cells with instructions that allow the cells to make the S protein. In this way, the vaccine familiarizes the immune system with this type of protein so that it can defeat it in the event of an infection.

The National Institute of Public Health – National Institute of Hygiene recalls: “The vector is safe, it has been selected in such a way that it does not reproduce in the human body and does not show any infectious properties”. It also does not affect or interact with DNA.

Like genetic vaccines, vector vaccines are a relatively new technology. They have already been studied extensively in research on HIV and other diseases such as Ebola virus.

The vaccine developed by AstraZeneca uses an inactive particle of the adenovirus that causes colds in chimpanzees to trigger an autoimmune response in the body. This particle is a vector, i.e. it carries the SARS-CoV-2 spike protein, which triggers an immune system response. According to the manufacturer’s data on the Yale Medicine website, the vaccine is 76 percent. effective in reducing the risk of symptomatic disease (15 days or more after receiving two doses) and almost 100% effective against the severe course of COVID-19. In the case of people 65+, the vaccine in 85 percent. prevented the disease.

AstraZeneca can be stored at 2-8ºC for up to six months.

The second available vector vaccine against COVID-19 is a formulation developed by Johnson & Johnson. It is based on a properly modified adenovirus 26 that can enter cells but cannot replicate in them. It is also a vector for the SARS-CoV-2 coronavirus spike protein. The vaccine causes the immune system to produce antibodies in response to a ‘foreign’ protein. The vaccine is characterized by 85 percent. effective in preventing severe COVID-19.

The preparation developed by Johnson & Johnson can be stored at 2-8ºC for three months. What distinguishes it from other vaccines is the fact that one dose is enough to obtain immunity, not two as in the case of other preparations.

The effectiveness of vector vaccines in preventing hospitalization is approx. 92%.

Finally, let us recall the words of Deputy Minister of Health Waldemar Kraska: – All vaccines available on our market are safe and effective vaccines. We have been repeating it for many months and it is true – he said in TVP Info at the end of May. – It doesn’t really matter which vaccine we get vaccinated with. It is important that this vaccination takes place – emphasized the deputy minister.

The editorial board recommends:

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The content of the medTvoiLokony website is intended to improve, not replace, the contact between the Website User and their doctor. The website is intended for informational and educational purposes only. Before following the specialist knowledge, in particular medical advice, contained on our Website, you must consult a doctor. The Administrator does not bear any consequences resulting from the use of information contained on the Website. Do you need a medical consultation or an e-prescription? Go to halodoctor.pl, where you will get online help – quickly, safely and without leaving your home.

The content of the medTvoiLokony website is intended to improve, not replace, the contact between the Website User and their doctor. The website is intended for informational and educational purposes only. Before following the specialist knowledge, in particular medical advice, contained on our Website, you must consult a doctor. The Administrator does not bear any consequences resulting from the use of information contained on the Website. Do you need a medical consultation or an e-prescription? Go to halodoctor.pl, where you will get online help – quickly, safely and without leaving your home.