Will the vaccines work against new variants?

Genetic mutations have been noted in the COVID-19 virus, with variants in the United Kingdom (B.1.1.7), South Africa (B.1.351), Brazil (P.1), all of which are now in the United States. In addition, new variants have been found in New York City (B.1.526) and California (CAL.20C).

Scientists are rushing to study the efficacy of the vaccines with these new variants. Most of the current vaccines appear to still be effective against the variants, though reduced efficacy was seen depending on the vaccine and the variant:

Moderna and Pfizer-BioNTech have done in-vitro testing which means they have used sera from vaccinated individuals to test against the new strains:

  • Moderna: in-vitro studies found that the vaccine produced neutralizing titers against all key emerging variants tested, including B.1.1.7 and B.1.351, first identified in the UKand Republic of South Africa, respectively. The study showed no significant impact on neutralizing titers against the B.1.1.7 variant relative to prior variants. A six-fold reduction in neutralizing titers was observed with the B.1.351 variant relative to prior variants. Despite this reduction, neutralizing titer levels with B.1.351 remain above levels that are expected to be protective.
  • Pfizer-BioNTech: in-vitro studies on key mutations from the U.K and South African variants found that the vaccine elicited antibodies, although with a reduced response to the South African variant. In a new preliminary study published February 17, the vaccine was found to have a 66% decrease in neutralization capabilities for the South African variant.  However, because the onset of protection after one dose of the vaccine precedes the development of high neutralizing titers, and the vaccine also elicits CD8+ T-cell responses it is unclear how this neutralization reduction will affect efficacy of the vaccine.
      • 57% effective in preventing moderate to severe cases in South Africa, where the variant dominates; 89% effective in protecting against severe disease in all regions studied.

Johnson & Johnson (clinical trial results)

  • 57% effective in preventing moderate to severe cases in South Africa, where the variant dominates; 89% effective in protecting against severe disease in all regions studied.
  • This vaccine was found to have similar efficacy for the U.K. variant than the original strain; however, in South Africa, it was found to have low efficacy for mild to moderate COVID-19, causing concerns that it is not effective against that variant; because the study was small and had young and healthy participants, it could not assess for efficacy against moderate to severe COVID-19.

AstraZeneca-Oxford

  • This vaccine was found to have similar efficacy for the U.K. variant than the original strain; however, in South Africa, it was found to have low efficacy for mild to moderate COVID-19, causing concerns that it is not effective against that variant; because the study was small and had young and healthy participants, it could not assess for efficacy against moderate to severe COVID-19.

Novavax

  • 89.3% efficacy in Phase 3 UK trial with over 50% of cases attributable to the now-predominant UK variant and the remainder attributable to COVID-19 virus.
  • 49.4% efficacy in total study population (60% efficacy in 94% of the study population that was HIV negative) was demonstrated in Phase 2b South Africa trial with over 90% of sequenced cases attributable to prevalent the South Africa variant.

Efforts are already being to understand how a vaccine booster or changes in the vaccine itself can target these new variants.

  • Moderna will be evaluating three approaches to booster vaccination:
    • A variant-specific booster candidate, mRNA-1273.351, based on the B.1.351 variant first identified in South Africa.
    • A multivalent booster candidate, mRNA-1273.211, which combines mRNA-1273, Moderna’s authorized vaccine against ancestral strains, and mRNA-1273.351 in a single vaccine.
    • A third dose of mRNA-1273, the authorized Moderna vaccine, as a booster.
  • Moderna also plans to evaluate the variant-specific mRNA-1273.351 and multivalent mRNA-1273.211 as a primary vaccination series for those who are seronegative. Participants will be evaluated in a two-dose series.

Sources

Updated: March 3, 2021

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