Around 4,000 variants of COVID-19 viruses have been reported around the world, so it will be very important for all vaccine manufacturers, including Pfizer Inc and AstraZeneca Plc to improve their vaccines as per the various virus species.  

Near about a thousand coronavirus variants that cause COVID-19 have been reported under mutated species, including the highly popular British, South African and Brazilian variants which turned out to spread even more rapidly than others.  

The current vaccine won’t be as effective on these mutation variants, especially with severe illness.  

Pfizer-BioNTech, Moderna, Oxford-AstraZeneca and all other manufacturers are looking forward on how they can improve their vaccine quality to make sure that they are ready for any other emerging variant - there are about 4,000 variants have been reported around the world.  

While so many of these variants have come into existence as the virus mutates on replication, only a few of them are likely to be important and to change the virus in a substantial way, as told by the British Medical Journal. Novel coronavirus SARS-CoV-2 has taken the lives of almost 2.268 million people globally since it emerged in China.