As it turned out, when new strains emerged over the winter of 2020–21 in Brazil and South Africa and raised concerns that the existing mRNA vaccines might offer less robust protection against these new variants, Pfizer and Moderna were able to develop new constructs that targeted these mutant strains and get them into development in under a few months.38 The speed and adaptability of the mRNA approach demonstrated its superior utility. The companies were able to generate boosters for new variants as soon as scientists isolated the new viral sequences, and have the modified vaccines ready if
...more
