Last week, Oregon Health Authority updated its weekly breakthrough report to include breakthrough cases in people who have received booster doses of a COVID-19 vaccine. This new set of data shows how well booster doses can protect against COVID-19 infection and severe disease.

In the report, a graph divides case numbers into three categories, “unvaccinated,” “fully vaccinated” and “fully vaccinated + boosted.”

The yellow line on the graph above shows case rates per 100,000 unvaccinated people, the blue line shows case rates per 100,000 fully vaccinated people, and the new grey line shows case rates per 100,000 fully vaccinated + boosted people. As the chart makes clear, vaccines and boosters are effective at reducing the risk of COVID-19 infection.

Breakthrough cases

A breakthrough case occurs when someone tests positive for COVID-19 two weeks or longer after they’ve received their primary vaccine series or booster. In other words, the virus “breaks through” the vaccine’s protection. Some may worry that the existence of breakthrough cases alone means that the vaccines aren’t working.

But vaccines were not designed to block all cases of infection; they were designed to reduce transmission and more importantly, reduce the risk of hospitalization and death. When infections do occur, they occur at much higher rates in people who are unvaccinated. Breakthrough cases also tend to be milder, without requiring hospitalization.

Boosters and hospitalization

The main goal of the COVID-19 vaccines is to protect against severe disease and hospitalization, and they do that exceptionally well (especially third doses and boosters). Recent data from the Centers for Disease Control and Prevention (CDC) show that unvaccinated people are many times more likely to require hospitalization than people who are fully vaccinated or boosted.

Another CDC report shows that third doses of an mRNA vaccine (either boosters or third doses for immunocompromised people) improved protection against hospitalization significantly. For immunocompromised people who received a third dose in their primary series of an mRNA vaccine (Pfizer or Moderna), protection from hospitalization rose from 69% to 88%. For non-immunocompromised people whose third dose was a booster dose, protection from hospitalization rose from 82% to 97%.

The data are clear: Vaccines plus boosters are helping keep people in Oregon safe from COVID-19. If you’re looking for a booster dose, check out this frequently updated list of high-volume vaccine sites.

Fully vaccinated vs. fully vaccinated + boosted

You are fully vaccinated if you received:

• Two doses of the Moderna or Pfizer vaccines (three doses if you are immunocompromised)
• One dose of the Johnson & Johnson vaccine

You are eligible for a booster if you are:

• Age 12-17 and received two doses of the Pfizer vaccine (three doses if you are immunocompromised) more than five months ago
• Age 18 or older and received two doses of either the Moderna or Pfizer vaccine (three doses if you are immunocompromised) more than five months ago
• Age 18 or older and received one dose of the Johnson & Johnson vaccine more than two months ago

The CDC says you are “up to date” if you have received all recommended doses of a COVID-19 vaccine or booster when eligible.