DOH Study Hopes To Shed Light On COVID-19 Reinfection Rates

OLYMPIA, WA — We've been living with COVID-19 for nearly two years now, but there are still a lot of things we don't know about the coronavirus. One of the biggest lingering questions: how effective are our immune systems at preventing reinfection after a patient has already suffered through one bout of COVID-19?

As part of the ongoing effort to learn more about antibodies and COVID-19 reinfection, the Washington State Department of Health (DOH) is launching a new, weekly report which the agency says will hopefully give more insight into the issue.

“We are still learning about COVID-19 and the duration and strength of immunity following infection with this virus,” said Scott Lindquist, MD, MPH, state epidemiologist for communicable diseases. “Based on what we know from similar respiratory viruses, we expect some COVID-19 reinfections to occur.”

For the first issue of the report, which included data from Sept. 1 through Dec. 26, 2021, the DOH found that:

• Out of 264,520 cases statewide, 4,404 Washingtonians were reinfected with COVID-19.
• 223 of those reinfected patients, roughly 5.1 percent, had to be hospitalized during their reinfection.
• 22, or 0.9 percent, of the reinfected patients died.
  • Notably, this means reinfected patients appear to have a similar risk of death. 1.1 percent of all patients who caught COVID-19 in that same time period died.
• 2,640 patients with reinfections, 59.9 percent, were unvaccinated.

The DOH acknowledges that the data is likely incomplete, as it relies on patients who had both their original infection and second infection tested, diagnosed, and reported to the state. As a result, patients whose first or second infection was asymptomatic or not diagnosed were left out.

"COVID-19 reinfections do occur but are rarely identified," the study reads. "People with a reported reinfection make up 1.7% of all reported cases of COVID-19. This is likely lower than the actual number of reinfections, but we do not have sufficient information to estimate the actual amount at this time."

However, based on the study's early findings, the DOH says it believes that reinfection is likely dependent on several factors, including:

• Continued exposure to other people with COVID-19
• COVID-19 vaccination status.
• Underlying health conditions and other patient characteristics.

"While reinfection is relatively rare, the best protection against getting any COVID-19 infection is to get vaccinated, and then get a booster shot when eligible," the agency said in a news release. "Children between the ages of 5 and 11 are now eligible for the COVID-19 vaccine and should start their two-shot series immediately."

On Thursday, the DOH approved booster shots for patients ages 12 to 15. As of Jan. 2, health care providers across Washington have administered more than 12 million doses of the COVID-19 vaccine to more than 5.5 million people and 70.6 percent of the state's eligible population is fully vaccinated.

The weekly reinfection report will be posted on the Washington State Department of Health's COVID-19 Data Dashboard.