Declines in daily cases and deaths of COVID-19 have slowed. The most likely explanation for this is the spread of the B.1.1.7 variant combined with increases in mobility. In this week’s model, we have included reduced cross-variant immunity between ancestral variants and B.1.1.7 with the escape variants (B.1.351 and P1). Reduced cross-variant immunity does not yet have a large effect in the US but will have a major impact later in the year as the variants become more common throughout the country. 

In our reference scenario, we expect that declining seasonality and rising vaccination levels will reduce transmission to counteract the increases associated with the spread of B.1.1.7. However, our worse scenario shows that more rapid declines in mask use among the vaccinated and more rapid increases in mobility may lead to transmission remaining at current levels and daily deaths over 1,000 through to mid-June. If mandates are relaxed faster, the spread of B.1.1.7 could lead to increased cases and deaths as early as April and May. 

Given the unexpected lifting of mask mandates in Texas and Mississippi last week, our reference scenario may be optimistic and the increases may be even more severe than our worse scenario indicates. 

The most important strategies to manage the epidemic remain ensuring vaccine coverage through increasing vaccine confidence and speeding up vaccine delivery, and encouraging the public to continue to wear masks and avoid high transmission risk settings. 

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Questions?

Contact:

David Carter | Director, Health Care Finance & Policy

C 360.888.5702