The Moderna and Pfizer-BioNTech vaccines are significantly less effective against the B.1.351 variant, which has been recorded in 20 US states. A recent study published in Nature found that when compared to the original coronavirus, the percentage of protective antibodies needed to neutralize B.1.351 was 12.4 fold lower for Moderna’s COVID-19 shot and 10.3 fold lower for Pfizer’s.
The B.1.351 variant was first detected in South Africa in October 2020. Since then, it has spread across 42 countries, including the US, where it is circulating in at least 20 states, including California and Texas, reported the CDC.
Scientists from Columbia University found that one specific mutation referred to as E484K, appears to be a “major contributor” to the B.1.351 variant’s ability to evade the antibody response.
For this study, scientists took 10 blood samples from people who had received two doses of Pfizer’s vaccine, 28 days after their second dose, and 12 samples from those who had received two doses of Moderna’s vaccine, 43 days after their second dose. They then compared how well antibodies in the blood samples “neutralized” the original coronavirus, compared to real-life B.1.351 coronavirus variants.
The results found that Pfizer’s and Moderna’s shots were at least 10 times less effective against the B.1351 variant with the E484K mutation. It’s important to note that the sample size of this experiment was small. In addition, antibody response is just one aspect of the immune response, so it remains unclear how well the vaccines work against the variant in real life.
For now, both companies have said that they are working on developing booster shots specifically to tackle the problem.