Question: How much of the current spike in infections do we think is related to holiday visits and how much to more contagious strains?
Answer: To my knowledge, most epidemiologists believe that the recent surge in infections in the US was the result of human behavior rather than a more contagious variant. The fact that cases and hospitalizations have been falling in the last couple of weeks lends credence to this hypothesis. However, most public health professionals (including me) are very concerned about the potential for cases, hospitalizations, and deaths to begin rising again because of the new, more contagious variants. This possibility is all the more fraught because the US’s genomic sequencing (e.g. surveillance for variants) has been paltry. We have been nearly blind to new variant development and spread in the country.
We likely have much more of the UK variant and other variants circulating than we currently know. As of 27 January, CDC has found a total of 315 cases caused by the UK variant (B.1.1.7) in 28 states across the US. This total represents *only* those cases identified through a sampling of SARS-CoV-2 positive specimens; it does not represent the true total. The US has been behind in genomic sequencing efforts, ranking 43rd in the world. As Nature reported earlier this month, “The number of SARS-CoV-2 genomes that the United States has shared on GISAID [global virome sequencing database] is less than 0.3% of its total number of COVID-19 infections. That compares with nearly 5% for the United Kingdom, 12% for Denmark, and almost 60% for Australia (see ‘Global surveillance’).” The lack of a national system means that individual academic laboratories do most sequencing rather than the country’s large genomic centers; states with many active sequencing labs are likely to discover more circulating variants and states with fewer sequencing labs may be totally blind.
It’s imperative that we double down on public health measures– social distancing, mask wearing, hand washing, avoiding crowded places, closed spaces, and close-contact settings– while increasing vaccinations and expanding our genomic sequencing efforts to keep the new variants from ripping through our weakened country. In that vein, the Biden administration has committed to expanding genomic surveillance with CDC currently working to double sequencing efforts.