David Ojcius
- Jul 5, 2021
- 2 min read

The fast-spreading Delta virus is now dominant in California and at least 4 other US states

Experts say that the fast-spreading #DeltaVariant of the #coronavirus is now dominant in California & at least 4 other US states (Iowa, Arkansas, Missouri & Utah).

Data shows that the Delta variant of the coronavirus is already dominant in five states of the US.

The variant, which is more transmissible than previous ones, has now reached all 50 states in the US. It is set to become dominant in the country over the next couple of weeks, according to expert projections.

Some states are further along the curve than others. Data suggests it has already taken over in at least five. This includes California, the most populous state.

A variant is considered dominant once it causes a greater proportion of infections than any other. It can reach this level before accounting for 50% of cases, though nations where Delta has existed the longest are registering close to 100% dominance.

California

The Delta variant makes up 35,6% of all cases, according to the latest available data from the California Department of Public Health. That is higher than the previously dominant variant Alpha, which made up 34,3% of cases.

Iowa

53% of cases sequenced in the week of June 21 were Delta variants, according to KWWL.

Arkansas

56% of Arkansas cases were due to Delta as of June 24, according to Action 5 news.

Missouri

As of Wednesday, the variant made up about half of the cases in Missouri, according to St. Louis Public Radio.

Utah

70% of cases sequenced on the week of June 13 were Delta variants, according to Utah department of health data.

In the graph below, the variants are called by their scientific names. Delta, or B1.617.2, is orange, while Alpha, or B.1.1.7, is green.

The variant could already be dominant elsewhere

It is likely that the variant is dominant in more states. Data reported here is from infections recorded a few weeks ago, a lag caused by the length of time taken to collect and analyze the data.