South African Strain Arrives

 

South African Strain Arrives

The first cases of a coronavirus variant that may better elude existing vaccines were reported in South Carolina yesterday. The two patients had no recent travel history, suggesting the strain has already achieved community spread in the US. 

The SARS-CoV-2 virus has undergone thousands of mutations during its global spread (see visualization)—most emerge and quickly fade—though scientists remain concerned about three in particular. These strains, from the UK, Brazil, and South Africa, do not appear more lethal but have been observed to spread more quickly. See an overview of the major variants here.

A COVID-19 vaccine from Moderna showed a sixfold reduction in the levels of neutralizing antibodies produced in the presence of the South African strain; Pfizer said early data suggested a slight decrease in the efficacy of its vaccine. In both cases, the vaccines remained overall effective in fighting the virus.

Both vaccines currently available in the US use messenger RNA technology—essentially using small pieces of genetic code to mimic the virus and stimulate the immune system. This approach is adept at fighting mutations, as scientists can effectively update the genetic code to reflect new strains. Moderna has begun clinical trials of booster shots to fight the emerging variants.

Novavax released data yesterday showing its vaccine was almost 90% effective in protecting against COVID-19—except against the South African strain, against which the efficacy dropped to under 50%. The Novavax vaccine uses proteins, not mRNA (see how it works).

The US has reported 433,195 total COVID-19 deaths, with 4,000 deaths reported yesterday. A total of 48 million vaccine doses have been distributed, with 26 million doses administered as of this morning. In positive news, the rate of new cases continues to fall, down almost 40% from mid-January.