Delta Explained: What You Should Know, and Do

This news article has been archived.

Shared courtesy of King County Public Health

The Delta variant is the latest example of how adaptable viruses can be. It’s a faster, more efficient version of the original virus that causes COVID-19. It’s the same virus, only better at infecting people.

Delta is far more contagious than its predecessors. It is spreading twice as quickly as the original strain, and people who are infected with it carry around much more virus in their nose and throat.

Now it is the most common COVID-19 strain spreading in King County and most of the US. As it spreads, the numbers of new cases and hospitalizations have been rising in the county, the state, and the nation.

Getting vaccinated is the best defense we have against COVID-19, including against the Delta variant strain. Vaccination makes it far less likely for someone to catch or spread the virus.

No vaccine is 100 percent effective, however, so the Delta variant can infect vaccinated people. But they are far less likely to have severe symptoms. Many have no symptoms at all.

These “breakthrough cases” are relatively rare. When vaccinated people do get infected with the Delta variant, they can be contagious and spread the virus to others, including to unvaccinated people who are at higher risk of getting seriously ill.

Anyone who has symptoms of COVID-19 (even if they are mild) or has had close contact with someone who is sick with COVID-19, should get a COVID test and stay away from others while they wait for results.

Getting vaccinated is the best protection

The main purpose of the vaccines is to prevent serious illness, and the COVID-19 vaccines are highly protective against serious illness leading to hospitalization or death.

Changing health guidance can be frustrating and confusing. It was only weeks ago, as summer began, that the state reopened and lifted most mask and social distancing requirements.

But as the virus adapts, so too must the guidance public health officials offer to keep the entire community safe.

That’s why the CDC, Washington state and King County health officials are again recommending that everyone, regardless of vaccination status, return to wearing masks in indoor public spaces, especially in areas where COVID-19 is spreading quickly.

If you’re in a private or restricted setting where you know everyone is vaccinated, you don’t necessarily need to wear a mask indoors, but you may choose to do so to reduce your risk further, especially if the space is crowded or the ventilation is poor.

For people who have not been vaccinated, masking up in public spaces remains mandatory.

Remember, not everyone can get the vaccine, including children under age 12.

Public Health is committed to achieving high vaccination rates across all neighborhoods and populations in King County, and we are targeting our resources accordingly.

The most important tool for limiting the spread of COVID-19 and protecting everyone in our community is getting vaccinated. To reduce risk, it’s also important to:

  • Wear a high quality, well-fitting mask in indoor public settings
  • Improve indoor air quality and ventilation
  • Stay home when ill, isolate from others, and get tested right away if exposed
  • Maintain physical distancing in crowded settings, especially indoors


Español — Spanish


Share Delta Explained: What You Should Know, and Do on Facebook Share Delta Explained: What You Should Know, and Do on Twitter Share Delta Explained: What You Should Know, and Do on Linkedin Email Delta Explained: What You Should Know, and Do link

COVID-19 information pages are no longer updated. 

See the CDC's COVID website for current information and trends. 

<span class="translation_missing" title="translation missing: en-US.projects.blog_posts.show.load_comment_text">Load Comment Text</span>