A week ago, another biotechnology company "Moderna" announced the preliminary results from its COVID-19 vaccine clinical trial. The results show the effectiveness of almost 95% against coronavirus infection.
The results are similar to Pfizer's vaccine results that showed more than 95% effectiveness, and the mode of action of the vaccine is also similar; they both use mRNA vaccine.
The vaccine, as many other vaccine candidates, targets coronavirus spike proteins which is a surface protein the virus uses to penetrate the host cells; mRNA vaccines use mRNA, which is the base sequence that carries the information for making spike proteins, instead of using the whole virus.
mRNA vaccines are injected into the immune cells, providing them with the information needed for making copies of the spike protein as if they were infected with the coronavirus. Then other immune cells get to develop immunity against the spike protein so as when the body is infected with coronavirus the immune cells can fight it and end the infection.
The mRNA vaccines are easier to develop than using the entire virus as a vaccine, which allowed companies to develop the vaccine in a short time.
The Moderna clinical trial included 30,000 volunteers, of which a quarter of them are 65 years or older, 63% are white people; 20% are Hispanic; 10% are Black, and 4% are Asian Americans. The efficacy and safety of the vaccine were the same among these diverse subgroups, but this finding will yet to be confirmed when the trial advances.
The trial included giving some of the participants the vaccine while others were given a placebo; the trial was blinded, meaning that none of the two groups nor the researchers knew who took what. The preliminary results were of the first 95 participants who got sick, of which 90 of them had taken a placebo, and 5 of them had taken the vaccine which calculates to 94.5% efficacy.
Also, from the 95 participants who got sick, only 11 had severe symptoms, none of which were vaccinated, suggesting that the Moderna vaccine doesn't only protect from the infection but also lower the severity of the disease for people who do get sick.
Another important announcement made recently by Oxford University, saying that their vaccine shows 70% effectiveness against coronavirus infection, which is still considered a significant percentage, and it can reach 90% by increasing the dose. However, the Oxford vaccine has a great advantage in that it can be stored at fridge temperature, making it cheaper, easier to be stored, and to reach different parts of the world than the other two vaccines.
The Oxford university vaccine is not an mRNA vaccine as the other two vaccines but is a genetically modified common cold virus that infects chimpanzees. It has been modified to stop infecting humans and carry the information for making coronavirus spike proteins.
Having many vaccine candidates gives us more hope that soon this pandemic may end.
Sources: New York Times, Moderna, BBC
