Highly Infectious Omicron Variants Fueling COVID-19 Case Increases

Increases in new Omicron variants continue to fuel high transmission in LA County, with cases and hospitalizations currently much higher than they were at this time last year, showing just how infectious the current Omicron variants and sub-lineages are. 

For specimens collected for the week ending May 21, 98% of specimens continue to be BA.2 and its sublineages. However, the proportion of the BA.2 Omicron variant itself, excluding its sublineages, appears to be plateauing, and continues to account for about half of the specimens sequenced in the county. The BA.2.3 Omicron sublineage has decreased, accounting for only about 3% of specimens in the most recent week. In contrast, BA.2.12.1 sublineage accounted for 42% of positive sequenced specimens, a small increase from the previous week. Nationally, the Centers for Disease Control and Prevention or CDC predicts that BA.2.12.1 will account for 62% of specimens collected the week ending June 4.

The BA.4 and BA.5 subvariants continue to remain rare in LA County, but a few cases are being detected every week. To date Public health has detected a total of 49 positive, sequenced specimens of these two subvariants – 27 of BA.4 and 22 of BA.5. The CDC estimated that, across the country, these two variants combined may have increased from about 1% to 13% of specimens collected in the past month. This suggests they may have the ability to outcompete other circulating variants. There is also concern that they may be able to cause re-infections in people who have already been infected by other Omicron subvariants.

The average number of daily new cases reported over the last seven days increased to 4,847 from one month ago when the average number of cases reported was 2,793 – an increase of 74%. The current high case numbers are also in stark contrast to the average number of cases last year, nearly 25 times higher, as there were only 190 average daily new cases in the middle of June 2021.

The current seven-day average test positivity rate, at almost 5%, continues to be higher than it was a month ago when the seven-day average test positivity rate was 2.7%.

The highly infectious variants and sub-lineages fueling the recent higher case numbers have translated to more than double the number of people severely ill and needing to be hospitalized than a month ago.

Over the last seven days, the average number of COVID-positive patients per day in LA County hospitals was 580, an increase of 124% from one month ago when the average number of COVID-positive patients per day was 259.

Deaths, which typically lag hospitalizations by several weeks, while still low, are beginning to slightly increase at an average of seven deaths reported per day this past week. One month ago, on May 13, there was an average of four deaths reported for the previous seven days.

Details: http://www.publichealth.lacounty.gov