With coronavirus cases spreading rapidly throughout California and the nation, reports of infections among those who are fully vaccinated for COVID-19 are increasingly drawing attention.
But while these “breakthrough” cases are sometimes highlighted as a precautionary tale - a signal of the shots’ shortcomings - the reality, experts say, is that the vaccinations remain as consistently effective as ever where it counts: protecting people against severe illness.
That remains true, officials say, even as Los Angeles County health officials shared a seemingly ominous data point Thursday: 20% of newly diagnosed coronavirus cases in June occurred among vaccinated people. Less than two weeks ago, they said over 99% of COVID-19 cases were among the unvaccinated.
At first blush, these numbers may seem to disagree with each other. But a closer look at the data underscores some key findings cited by public health experts, epidemiologists and infectious disease experts in California and by federal officials.
There are two things occurring: More than half of Californians are now fully vaccinated, yet coronavirus transmission has gone up. And while coronavirus case rates are rising in both vaccinated and unvaccinated people, the rates continue to be much worse in unvaccinated people — a trend that’s expected when viral transmission rises.
Why are there cases among vaccinated people increasing?
The following two statements can be true at the same time:
Between Dec. 7 and June 7, the unvaccinated accounted for 99.6% of L.A. County’s coronavirus cases, 98.7% of COVID-19 hospitalizations and 99.8% of deaths.
Out of all coronavirus cases confirmed countywide in June, 20% occurred in residents who were fully vaccinated.
The first sentence speaks to the extraordinary effectiveness of the vaccines. Yes, the period between Dec. 7 and June 7 does cover a time period when vaccine supply was limited. But it also provides a viewpoint into what hospitals are seeing and explains why doctors are so convinced at the effectiveness and importance of the vaccines: Extraordinarily few hospitalizations and deaths have occurred among vaccinated people.
The latter percentage is not so surprising as it might initially seem.
Say, for instance, there were roughly 1,000 coronavirus cases in a month among fully vaccinated people, and there were 4,000 more coronavirus cases among people who were either unvaccinated or partially unvaccinated. In this community, a population of 10 million people was split: Half were vaccinated, and half were not.
One could focus on how 20% of the coronavirus cases occurred among vaccinated people.
But one could also point out that how, for every 100,000 residents, 10 vaccinated people tested positive, and 40 unvaccinated people tested positive. That means unvaccinated people, in this hypothetical example, are four times as likely to test positive for the virus.
Statewide, officials note that while there are instances of vaccinated people becoming infected, the risk remains much more pronounced for the unvaccinated.
From July 7 to 14, the average case rate among unvaccinated Californians was 13 per 100,000, according to the state Department of Public Health. Among those who had been vaccinated, the comparable figure was 2 per 100,000.