Vaccine breakthrough cases are expected. COVID-19 vaccines are effective and are a critical tool to bring the pandemic under control. However, no vaccines are 100% effective at preventing illness in vaccinated people.
Of the 524,838 fully vaccinated Delawareans, there have been 4,683 breakthrough cases of COVID-19, roughly 9 tenths of 1 percent.
The number of breakthrough cases and the number of fully vaccinated Delawareans are updated once per week on Fridays when the data becomes available, which may be after the rest of the data is published.
Trend Comparison: Fully Vaccinated and Deaths among All Delawareans
Data are current as of 6pm the previous day. Last update: 10/19/2021
Percent of persons testing positive, and percent of tests that are positive are helpful indicators in understanding the spread of infection in a community. Percent of persons testing positive indicate one result reported for each individual tested (positive or negative), even if that person is tested more than once with the same result. As a result, it often reflects higher positivity rates.
Percent of tests that are positive indicates the total number of specimens tested, including when an individual is tested more than once, and reflects higher reported test numbers and lower positivity rates. It is also more widely used by other states and the Federal government, and is therefore useful to compare Delaware to other jurisdictions.
Because of the increasing frequency of repeat testing, using person-based percent positives could be misleading on a daily basis. Therefore, using the percent of tests that are positive is a more useful measure to make operational decisions. Data for percent of tests that are positive are based on the testing date, while data for persons testing positive is based on the date results are reported to DPH. There is a two-day lag for presenting data related to percent of tests that are positive to account for the time delay between the date of the test and the date that DPH receives the test result.