Officials with DC Health said the relatively low rate of cases where vaccinated residents come down with COVID-19 — known as breakthrough cases — are an encouraging sign that the vaccines are effective and safe.
The Centers for Disease Control and Prevention (CDC) classify a breakthrough case as a patient who is hospitalized with COVID-19 despite being fully-vaccinated. Locally, D.C. health officials count any fully vaccinated person who tests positive for COVID-19, regardless of whether or not they are hospitalized.
Around .05% of the 375,988 fully vaccinated D.C. residents have experienced a breakthrough case, with 13 of those cases directly resulting in hospitalization and four resulting in death. Around 57% of those who tested positive for COVID-19 were symptomatic, though the majority of those did not need to be hospitalized.
“This does not mean the vaccines did not work for these individuals … the really great thing about our vaccines is how effective they are in preventing hospitalizations, severe disease and death,” said Patrick Ashley with DC Health. “So you could make the argument that those asymptomatic individuals who are positive likely could have had symptoms or got really sick. Those symptomatic individuals, who maybe just had some cold-like symptoms as opposed to having respiratory failure in the hospital.”
The four D.C. residents who died from breakthrough cases of COVID-19 all had histories of medical illnesses and three of them were over the age of 65, according to Ashley.
D.C. will be tracking these breakthrough cases in a new dashboard on the District’s website unveiled on Thursday. It will be updated every two weeks, which officials say will give them enough time to properly investigate each breakthrough case.
Dr. Ankoor Shah with DC Health said breakthrough cases are inevitable with any vaccine, and the low rate of them seen so far gives him confidence in the effectiveness of the vaccines.
“No vaccine is 100% effective, but this vaccine continues to show it is highly effective in preventing COVID-19, in preventing severe illness leading to hospitalization and in preventing death,” he said. “When I look at this data, my confidence only grows in the effectiveness of our vaccines and in the safety of them as well.”
The data also shows that most breakthrough cases recorded in the District so far have occurred within the first three months from the date of the person being vaccinated. Ashley said while there has not been enough time yet to fully interpret this subset of data, it would be worth tracking heading into the fall.
“I think the assumption we all had before going into this is: After a certain number of months, does your immunity ‘wane,'” he said. “Well in our data, we see that a larger percentage of individuals who had a breakthrough case occurred in the first few months.”