By Brenda Goodman
As SarsCov2 continues to evolve, drug manufacturers are racing to adapt their vaccines to changes in the virus's genetic code that appear to help it escape our immune defenses.
Of the three "variants of concern" recognized by the World Health Organization and the Centers for Disease Control and Prevention, studies have shown that the mRNA vaccines created by Pfizer/BioNTech and Moderna, as well as the Novavax vaccine, remain highly effective against the B .1.1.7 variant, which was first recognized in the UK.
mRNA vaccines are 4 to 7 times less effective against the P.1 variant, which was first discovered in Brazil, but still appear to be within a significant "buffer of protection," particularly after two doses, and should prevent the disease, according to Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases.
The B.1.351 variant is more problematic. Studies have shown that the AstraZeneca vaccine was 86 times less effective against this variant, which was first detected in South Africa.
mRNA vaccines are 6 to 8 times less effective against this variant, suggesting a significant decrease in protection. In clinical trials in South Africa, the Johnson & Johnson vaccine also showed reduced efficacy in populations where this variant was increasing.
Johnson & Johnson, Moderna, and Pfizer are exploring options to make their vaccines more effective against variants.
Johnson & Johnson is giving trial participants a second dose of its original one-dose vaccine to see if a booster might make it more effective. It is also developing new, derivative vaccines to be more effective against the variants.
Pfizer is testing a third dose of its initial vaccine to see if it will increase protection enough to prevent infection from new strains. It is also reformulating its vaccine to produce antibodies against the new variants.
Moderna and Novovax have also announced they will develop multivalent, strain-specific vaccines to better target the variants, according to The Wall Street Journal. AstraZeneca has also committed to developing next-generation vaccines against the variants.
Source : New England Journal of Medicine . March 23, 2021.