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As the virus that causes COVID-19 continues to evolve, drugmakers are racing to adapt their vaccines to the changes in the virus’ genetic code that appear to help it escape our immune defenses.
Of the three “variants of concern” recognized by the World Health Organization and 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 United Kingdom.
The mRNA vaccines are 4- to 7-fold less effective against the P.1 variant, which was first discovered in Brazil, but they still appear to be within an important “cushion of protection,” particularly after two doses, and should prevent disease, according to Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases.
The B.1.351 variant is more troublesome. Studies have shown that the AstraZeneca vaccine was 86 times less effective against this variant, which was first detected in South Africa.
The mRNA vaccines are 6- to 8-fold less effective against this variant, suggesting a significant waning of protection. In clinical trials in South Africa, the Johnson & Johnson vaccine also had less efficacy in populations where this variant was surging.
Johnson & Johnson, Moderna, and Pfizer are all exploring options to make their vaccines more effective against the variants.
Johnson & Johnson is giving trial participants a second dose of its original one-dose shot to see if a booster might make it more effective. It’s also designing new derivative vaccines to be more effective against variants.
Pfizer is testing a third dose of its initial vaccine to see whether it will increase protection enough to prevent infection from new strains. It’s also reformulating its vaccine to produce antibodies against the new variants.
Moderna and Novovax have also announced that they will develop strain-specific multivalent vaccines to better take on 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.
Créditos: Comité científico Covid