Day 133: Attack of the Mutant Spike Protein

The New York Times reports on a preprint about a mutation (D614G) in the SARS-CoV-2 spike protein making it more stable, and therefore, possibly, more infectious. This spikier mutant coronavirus has become predominant over time, especially in Europe and the northeastern US, but was not present in earlier outbreaks in the northwestern US.

A press release at Scripps about the paper discusses some reasons why many researchers have picked up on the mutation itself without establishing whether it contributed to the virus's fitness or merely spread through founder effects. While they feel they've established increased infectivity of the mutant virus in the lab, they stop short of claiming that the result definitely holds under real world conditions.

Interestingly, the paper itself discusses the "natural" history of the furin-cleavage site (which PlagueBlog readers may recall also figures into unnatural histories of SARS-CoV-2) and how this previous change gave rise to the need for more stability in the spike protein that would have favored a mutation like the one under discussion. Their point stands regardless of how the furin-cleavage site made it into the virus.

Elsewhere on the research front, an Indian study of hydroxychloroquine as a prophylactic treatment has shown promising results. A comparative study of BCG, pneumonia, and flu vaccination found reduced mortality associated only with the BCG (tuberculosis) vaccine. Also, the asthma question has an answer in pre-proof: a study by the Harvard School of Public Health found that non-allergic asthma increased the risk of developing severe COVID-19, but that allergic asthma did not.

Some correspondence to the Lancet concludes against herd immunity based on very little evidence and some rather questionable assumptions ("probable similar previous exposure to other human coronaviruses", "lockdown would not alter the herd immunity threshold in the population or the ultimate death rate per capita"). Demographic differences between European countries were explicitly brushed off, and other differences (superspreading history, spikier viral mutations, etc.) were not even considered.

Massachusetts cases are up a third of a percentage point today.