Currently, worldwide, five vaccines, which had started phase III studies at an early stage, are in production by three different methods.

These methods are:

1.Inactivated Vaccines
•Produced with the conventional methods.
•Contain an inactivated (killed/non-active) virus with no ability to cause disease. These stimulate the immune system without any risk of developing the disease.
•Their long-term effects are more studied and predictable compared to the other vaccines.
•They are generally considered to be safer than the others because they contain inactivated (killed) viruses.
•They can be stored at 2-8°C in conventional vaccine refrigerator cabinets in routine use.
•Their production is a more difficult and slower process than the others.
•The vaccine efficacy of the inactive vaccine undergoing phase III trials in Turkey was found to be 91.25% according to interim evaluation results.
•Sinovac vaccine falls into this class.

2.Viral Vector (Adenovirus) Vaccines
•Designed to create immunity by using a specific virus (adenovirus) causing a flu-like disease, which gets genetically modified with the insertion of the coronavirus protein.
•Vaccines of this type were initially developed against some viral diseases such as Zika, Chikungunya and have been in phase III trials for a long time.
•Although these vaccines contain live viruses, the microorganisms cannot cause disease in humans since they are weakened.
•Their logistical advantage is that they can be stored between 2-8°C, i.e. in conventional vaccine refrigerator cabinets in routine use.
•This method is one of the new state-of-the-art vaccine development technologies. 
•Sputnik-V and Oxford/AstraZeneca (AZA-1222) vaccines fall into this class.

3.Messenger RNA (mRNA) Vaccines 
•mRNA is normally involved in protein synthesis in our bodies.
•Artificially produced mRNAs in the laboratory aim to train our immune system, against the virus by working just like our own mRNAs.
•These proteins are subsequently broken down in our cells and removed from the body like our own proteins.
•These vaccines feature technologies operating on a principle similar to the one that has been under development for the last 25 years for individualized immunotherapy, used against cancer and other diseases.
•The biggest logistical disadvantage of these vaccines is that the Biontech/Pfizer vaccine (BNT-162b2) can only be stored at -70°C, while the Moderna vaccine (mRNA-1273) can only be kept at -20°C.
•Biontech/Pfizer and Moderna vaccines fall into this class.

* Currently, studies on 16 different vaccines are in progress in Turkey.