Updates on the Delta variant

There’s been talk in the news and online about the B.1.617.2 (Delta) variant — what it is, where it has spread and whether it’s something to be concerned about. Here’s what you need to know.

Delta variant defined

The Delta variant is classified by the Centers for Disease Control and Prevention (CDC) as a “variant of concern” (VOC).

Variants are changes to a virus through mutation; they occur regularly. Many variants of the virus that causes COVID-19 have been documented in the United States and globally during this pandemic, but CDC has designated only a few as “variants of concern” because we have evidence that they either spread more readily, cause more severe disease or evade testing, therapies or vaccination. According to the CDC’s website, the Delta variant spreads much more easily than other COVID-19 variants. The CDC also states that the Delta variant may have resistance to monoclonal antibody treatments and vaccination.

The CDC and Oregon Health Authority (OHA) have been closely monitoring VOCs — including the Delta variant — throughout the pandemic and all vaccines authorized for emergency use in the U.S. remain effective against all COVID-19 variants, including the Delta variant.

How the Delta variant is spreading

While it’s welcome news that vaccinations are effective in preventing infection from COVID-19, that doesn’t mean that the Delta variant isn’t still spreading.

According to the CDC’s COVID Data Tracker, the Delta variant accounted for an estimated 30% of all variants circulating nationally in the 2-week period ending June 19. This represented a significant increase over the previous 2-week period ending June 5, in which the Delta variant only accounted for an estimated 10% of all variants circulating nationally.

Oregon pulls its own variant surveillance data from GISAID — a public data repository. OHA asks all state partners performing sequencing — the process whereby scientists identify the COVID-19 virus and monitor its changes over time into new variants — to report their data to GISAID.

Oregon’s GISAID data shows that the Delta variant now accounts for at least 5% of all of Oregon’s COVID-19 cases (this number may change because sequencing data can take weeks to be reported).

The CDC estimates that the Delta variant will continue to spread in the weeks to come and this increase will also be seen in Oregon.

Delta’s spread hasn’t resulted in more breakthrough cases

Many have asked whether the Delta variant has caused an uptick in vaccine breakthrough cases in Oregon. Vaccine breakthrough cases are defined as instances in which an individual received a positive COVID-19 test result at least 14 days following the completion of any COVID-19 vaccine series. OHA is carefully monitoring vaccine breakthrough cases in Oregon and is actively studying this question in collaboration with the CDC.

On July 1, Oregon Health Authority released its latest monthly report on breakthrough cases, which demonstrated how effective COVID-19 vaccines are in preventing infection.

Fully vaccinated individuals are highly protected from COVID-19 infection. However, partially vaccinated and unvaccinated individuals remain susceptible to the harmful effects of the same virus.

For the month of June, Oregon reported 7,241 total cases of COVID-19. 92% of those cases occurred in unvaccinated individuals. Oregon also reported 63 COVID-19-associated deaths for the month of June. 94% of these deaths occurred in unvaccinated individuals.

As OHA Director Patrick Allen expressed in a June 4 press conference, Oregon is currently caught in a “tale of two pandemics.”

“The data clearly show that if you are fully vaccinated, you can begin to put the pandemic behind you,” said Director Allen. “But if you’re unvaccinated, the thread of COVID-19 still shadows your life.”

As the pandemic continues, state and local epidemiologists at OHA will continue to track all vaccine breakthrough cases and issue monthly vaccine breakthrough reports, which will be posted to the OHA website. Additionally, you can view breakthrough case data on OHA’s Daily Data Update dashboard.

Vaccine boosters still not recommended

Oregon Health Authority continues to endorse the recommendations of CDC and the Advisory Committee on Immunization Practices (ACIP) for COVID-19 vaccine dosing.

Under current conditions, the CDC and ACIP do not recommend administering booster doses of the COVID-19 vaccines. Furthermore, administering a booster to an individual would be outside the scope of the FDA emergency use authorization. Boosters recommended by a physician beyond the EUA scope should be discussed directly with the manufacturer and FDA

Vaccines given according to the currently recommended schedule continue to be highly effective in reducing the risk of serious illness from COVID-19. Observational data confirm that currently available vaccines are effective against new variants, including the Delta variant.

Under the provider agreements in the CDC COVID-19 Vaccination Program, providers are required to administer COVID-19 vaccine in conformance with CDC/ACIP guidance. Until the ACIP considers and recommends administration of additional doses, and CDC adopts their recommendation, providers will not be authorized to administer additional doses.

Get vaccinated

Vaccination remains the safest and most effective way for all people in Oregon to get back to doing the things they love. If you are 12 or older, visit OHA’s Find a COVID-19 Vaccine in Oregon webpage to schedule your vaccine appointment today.

Additional Resources

1. COVID-19 Variants – An overview of the Delta variant

2. COVID-19 Breakthrough Cases Q&A, June 23, 2021