Globally more than 200 Coronavirus vaccines are at various stages of development. About 10 are in phase three trials, meaning they are being tested on a large number of people in different regions and countries. Both Pfizer and Moderna vaccines use a new method involving mRNA. It involves injecting a tiny amount of the virus’s genetic code, which trains a person’s immune system to fight the Covid-19 virus if they come into contact with it.
One of the major differences between the two is that the Pfizer vaccine, which is given in two doses three weeks apart, has to be stored at 70 degrees Celsius, whereas the Moderna vaccine, given in two doses four weeks apart, can be stored at 20 degree Celsius. No mRNA vaccine has ever been approved for use in humans. The vaccine collaboration between AstraZeneca and Oxford University is based on a more traditional method by using a common cold virus from chimpanzees. Modified to carry the Covid-19 genetic information and to prevent infection in humans, it causes the immune system to produce Covid-19 antibodies. This approach has been used to create effective vaccines for diseases including Ebola and Flu. It is given in two doses and can be stored in a standard fridge.
The Sputnik vaccine is named after the Soviet-era satellite that triggered the space race and is designed to prompt an immune system response after two doses given 21 days apart. Similar in design to the AstraZeneca-Oxford vaccine, it uses two viral vectors- essentially the means to deliver genetic material into cells- that normally cause the common cold and carries the genetic code of Covid-19.
China’s Sinopharm vaccine, which has been approved for use in the UAE, is an inactivated vaccine- meaning it uses dead or weakened versions of the virus. It works by exposing the body’s immune system to the disease without causing serious illness. The technique has been used for decades to create many vaccines, including for polio. During the phase three trials in the UAE, the Sinopharm vaccine was administered to volunteers in two doses over 28 days. It is stored in the fridge at between 2 degrees Celsius and 8 degrees Celsius.
So how do the vaccines compare so far?
Moderna and Pfizer have both recorded efficacy protecting rates of 95 percent during trials, with Sputnik 92 percent effective, the Oxford-AstraZenca vaccine up to 90 percent effective, and the Sinopharm vaccine registering 86 percent efficacy rate, according to the UAE.
According to Dr. Muhammad Munir, Lecturer in Molecular Virology, Lancaster University said “we have to immunize at least 70 percent of the population and given that most of these vaccines have two doses. We are talking about 11 billion doses to be distributed throughout the world in every corner, with a lot of challenges. There are countries which are politically unstable; there are countries which are hard to reach. There are other issues that need to be tackled before we can really look at the extremely positive impact of these vaccines on ending this pandemic.
Just putting into the perspective, we have a very excellent vaccine against measles virus, against polioviruses, but just because of the distribution challenges, those are not yet being delivered to the corners of the world where it needs to be declared as eradicated. And primarily because there are logistic challenges, managerial challenges, and sometimes very political challenges. So, therefore, I am thinking what happens is that the biggest challenge after the availability of the vaccine would be to take it to the scale where it is needed to really see the impact of the vaccine to curtail the pandemic.
The challenge of developing a Covid-19 vaccine may be drawing to a close, but what remains to be seen is how long immunity will last. Lockdowns and other restrictions put in place by governments aim to prevent more people from becoming infected and dying. But scientists say successful vaccines will ultimately be the key to helping and the pandemic.
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