California COVID-19 Infection Rate is Growing Again

California (CA) had and still has one of the best records in the war against COVID-19 in the USA with less than half the national average infections per capita and just 13% that of New York State.  At the same time its economy has been hard hit so it has little choice except to try to reopen safely.  But since it started reopening some activities earlier this month, its infection rate has crept up.  Its 7-day trailing average daily rate has increased by 25% from 1,723 to 2,170 per day. 

California has published the most detailed demographic information about its confirmed cases and case fatality rate (CFR) which allows us to examine COVID-19 issues and trends in more detail.  The availability of more data confirms some of our major conclusions from our study earlier this month:
1.     Latinos continue to be infected at a higher rate than any other race/ethnicity, but their death rate is just average for the state.  This implies a lower CFR for Latinos (3.8%) than CA in general (5.4%) but after adjusting for age the difference disappears.  It turns out that the Latino population is much younger than average and a lot of young Latinos are getting infected but not suffering very much from COVID-19. 
2.    Blacks seem to get infected and die as often as everybody else (CFR of 9.8% vs 8.6% for whites).  However, after breaking out their data by age groups, middle-aged (35-65 yrs old) blacks seem to have twice the CFR of whites while CFR for the very oldest (85+) are about the same for all races and ethnicities (36%).  We suspect poorer health and comorbidities such as obesity and diabetes for many blacks may play a part but additional data will be needed to draw firmer conclusions. 
3.    Curiously, the CFR for Californians (purple line in the graph below) overall is not that different than for Europeans such as Italians and Spaniards implying that CA’s hospital system and population health may not be that great. CA’s CFR may be overstated because the actual infection rate may have been and continues to be higher than the number of confirmed cases.  But if so, this undercounting of confirmed cases could also afflict most other countries except South Korea, Australia, and other best in class countries in terms of testing.  South Koreans continue to set the lower benchmarks for CFR (see blue line in the graph below).  


California’s rising case count and increasing effective reproduction rate R = 1.1 is worrisome, but it may be a result of counting more asymptomatic and mildly symptomatic cases as testing protocols are relaxed.  CA has one of the better testing records of states in the US.  It has tested 4.2% of its population about the same as the US average but its tests have returned 5.8% positive cumulatively (better than 11.3% for the US as a whole) and in recent days, its tests have returned below 3% positives.  If it continues to expand its testing it may continue to reopen safely.  If it cannot, it must slow reopening until testing and contact tracing can catch up to return less than 1% positive results. 

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