Pfizer Inc and BioNTech's Covid-19 vaccine appeared to work against a key mutation in the highly transmissible new variants of the coronavirus discovered in the UK and South Africa according to a laboratory study conducted by the U.S. drugmaker. Those variants are causing global concern. They both share a common mutation called N501Y a slight alteration on one spot of the spike protein that coats the virus. That change is believed to be the reason they can spread so easily. What Is The Active Ingredient In The Pfizer Covid-19 Vaccine? The active ingredient is messenger RNA that carries instructions for