Just one-half of 1 percent of COVID-19 fatalities in England in the first six months of 2021 were breakthrough cases in fully vaccinated individuals, according to researchers.

Researchers at the U.K.’s Office for National Statistics released an analysis on Monday that examined the COVID-19 deaths reported between Jan. 2 and July 2.

The report found that of the 51,281 coronavirus-related deaths in that time frame, 256 were “breakthrough deaths,” which refers to individuals who test positive for the virus at least 14 days after receiving the second vaccination dose.

That number is equivalent to just 0.5 percent of the total number of COVID-19 deaths reported in the first six months of 2021.

Researchers found that the U.K. recorded 640 deaths from “breakthrough cases” between Jan. 2 and July 2. Among that group, however, some were infected before the protection from their second dose fully took effect.

The median age of people who suffered a breakthrough death was 84 years old. For other deaths overall — including from COVID-19 and other ailments — the median age was 82, according to the researchers.

Roughly 13.1 percent of the breakthrough deaths recorded in the time frame examined were among people who were identified as likely immunocompromised from hospital incidents or causes of death, according to the analysis. By contrast, 5.4 percent of other COVID-19 deaths were likely immunocompromised.

Roughly 61 percent of the breakthrough deaths recorded were male, according to the researchers.

Overall, coronavirus-related deaths accounted for 0.8 percent of all deaths among individuals who had been fully vaccinated in the six-month window of study. On the other hand, 37.4 percent of all deaths among unvaccinated individuals in the time frame observed were attributed to the virus.

The findings from the Office for National Statistics further bolster claims that COVID-19 vaccines are highly effective in preventing death.

The Moderna, Oxford-AstraZeneca and Pfizer-BioNTech vaccines are all available in England.

The Janssen single-shot vaccine has also been authorized in the U.K., but doses will not be available in the country for several months, according to the health ministry.