Serious coronavirus infections among vaccinated people have been relatively rare since the start of the vaccination campaign, a New York Times analysis of data from 40 states and Washington, D.C., shows. Fully vaccinated people have made up as few as 0.1 percent of and as many as 5 percent of those hospitalized with the virus in those states, and as few as 0.2 percent and as many as 6 percent of those who have died.
There is still a lot we do not know about so-called breakthrough infections — when fully inoculated people contract the virus. And there is some evidence that these cases are becoming more common as the more transmissible Delta variant surges. While vaccines have done a remarkable job at protecting a vast majority of people from serious illness, the data in the Times analysis generally spanned the period from the start of the vaccination campaign until mid-June or July, before the Delta variant became predominant in the United States.
Breakthrough Covid-19 Hospitalizations and Deaths by State
Among fully vaccinated people in each state since vaccination began.
|STATE||BREAKTHROUGH HOSPITALIZATIONS||AS A PCT. OF ALL COVID HOSPITALIZATIONS||BREAKTHROUGH DEATHS||AS A PCT. OF ALL COVID DEATHS|
Data on less serious breakthrough infections is not widely available, though it is possible those cases are rising. Data was not available for several states in which the virus has been surging, including Florida and Missouri.
Until recently, the Centers for Disease Control and Prevention estimated that fully vaccinated people accounted for less than 3 percent of coronavirus hospitalizations nationwide and less than 1 percent of virus deaths. But last week, the agency noted that those figures did not reflect new data involving the Delta variant and said it was actively working to update them. Only about 50 percent of people in the United States are fully vaccinated.
Looking at how many hospitalizations and deaths have involved fully vaccinated people is a common but crude measure of how well the vaccines are working.
As more people get shots, the percentage of hospitalizations and deaths among fully vaccinated people should rise. This may seem counterintuitive, so it’s important to understand why.
In a state with a high vaccination rate, a higher percentage of breakthroughs may simply reflect that fully vaccinated people are a bigger chunk of the population, or that there are few hospitalizations and deaths overall. Imagine a state where just two people are hospitalized but both are vaccinated — breakthroughs would account for 100 percent of the hospitalizations in that state, even though these cases were very rare.
Assessing breakthrough rates
Some epidemiologists and state health officials instead recommend comparing how likely a vaccinated person was to be hospitalized or to die, compared with an unvaccinated person.
To do this, the Times used the number of breakthroughs and the vaccination rate over time to estimate rates of hospitalizations and deaths for each group in every state for which data was available.
In those states, people who were not fully vaccinated were hospitalized with Covid-19 at least five times more often than fully vaccinated people, according to the analysis, and they died at least eight times more often.