Napa County reported its first COVID-19 death of a fully vaccinated resident earlier this month, even as the chance of experiencing a breakthrough infection remains exceedingly rare, public health officials said.
The Napa woman was older than 65 and had underlying health conditions, county officials said. She died June 2 after a prolonged hospital battle.
She had received the Moderna vaccine and had her second dose at least 30 days before testing positive for COVID-19, said Napa County spokeswoman Leah Greenbaum, citing information from the county’s epidemiology group.
The woman had tested positive for the B.1.1.7 variant — newly named the Alpha variant by the World Health Organization — which was first detected in the U.K. To date, the county has confirmed seven cases of the variant, which is believed to be more transmissible and potentially causes more severe illness than some other strains.
Public health officials said the vaccines are not foolproof but have dramatically lowered the number of coronavirus cases and COVID-19 deaths in the county. Napa County has reported just under 10,000 coronavirus cases and 79 deaths, with the average number of each dramatically dropping of late. Over the past week, the county has averaged just two new cases and 0.1 new deaths per day, according to Times data.
Of the more than 71,370 Napa County residents who were fully vaccinated as of late last week, 32 have exhibited symptoms and tested positive for the virus, according to county officials. That translates to a breakthrough infection rate of about .04%. The rate is similar to Los Angeles County, which had a .03% rate as of May 7.
“No vaccine is 100% effective, but this does not diminish the urgency and importance of getting vaccinated, especially as more variant strains emerge,” Napa County Public Health Officer Dr. Karen Relucio said in a statement, adding that overall, the vaccines “provide exceptional protection against death and illness.”
Still, breakthrough infections do occur. According to the Centers for Disease Control and Prevention, they’re expected, “especially before population immunity reaches sufficient levels to further decrease transmission,” a recent report states.
There are two primary driving factors behind the breakthrough infections, according to Dr. Edward Jones-Lopez, an infectious disease specialist at USC’s Keck School of Medicine.
Most commonly, coronavirus variants elude the vaccine immunity designed primarily to protect against what Jones-Lopez called the “ancestor virus,” or the original strain.
Though less common, a small number of people — such as the immunosuppressed and the elderly — are not able to mount as strong an immune response to the vaccine as the general population. For these people, the vaccine doesn’t work as it should.
“Despite being vaccinated, they’re unable to generate enough antibodies in protection against the virus,” he said.
Greenbaum said the situation underscores the importance of increasing vaccination rates in Napa County and beyond.
“Getting vaccinated helps protect us, and it helps protect vulnerable people who aren’t able to mount that immune response,” she said.
Though concerning, breakthrough infections tend to cause less severe cases of COVID-19 compared to infections in people who are not vaccinated, Jones-Lopez said.
“It’s really almost two completely different diseases,” he said, comparing COVID-19 cases before and after vaccinations.
Of the more than 135 million people who were vaccinated in the U.S. as of June 1, just over 3,000 were hospitalized or died from breakthrough infections by the virus, according to reports the CDC received from 47 states and territories.