Unvaccinated people still make up the vast majority of cases, hospitalizations, and deaths.
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Breakthrough cases aren’t the cause of the US Covid-19 surge
Unvaccinated people still make up the vast majority of cases, hospitalizations, and deaths.
The last week’s headlines were not comforting for Americans vaccinated for Covid-19.
The Centers for Disease Control and Prevention changed its
guidance to recommend everyone, regardless of vaccination status, wear masks in Covid-19 hot spots. A
study of an outbreak in Provincetown, Massachusetts, found around three-quarters of people infected there were vaccinated. As cases increase nationwide, it’s understandable to think that breakthrough cases (infections in vaccinated people) are now a main driver of the ongoing Covid-19 surge.
But the evidence is clear: The problem is the unvaccinated population. If more people got the vaccines, the current surge wouldn’t be as big; it certainly wouldn’t lead to the levels of hospitalization and death now seen across the US. This was true months ago, and remains true today.
Unvaccinated people still make up the vast majority of cases, hospitalizations, and deaths. They’ve made up more than 94 percent of reported Covid-19 cases in states with available data, a
report last week from the Kaiser Family Foundation found. They’ve also made up similar, or higher, shares of hospitalizations and deaths.
Then there’s what really happened in the Provincetown outbreak. The
headlines noted three-fourths of people infected by the virus were vaccinated. But among the more than 900 cases
tracked as a result of the outbreak, just seven led to hospitalization — and there were zero deaths. If this was 2020, when there were no vaccines, closer to 90 people would have been hospitalized and about nine would have died, based on hospitalization and death rates over the last year.
“The vaccines are upholding their promise to massively prevent serious disease, hospitalizations, and death,” Monica Gandhi, an infectious diseases doctor at the University of California San Francisco, told me. “That’s the main message I get from that outbreak.”
If every outbreak in the country today looked like the one in Provincetown, the coronavirus would be defanged. The virus would make a small number of people seriously ill, but, like the seasonal flu or a common cold, would mostly produce relatively mild symptoms or none at all.
That’s not to say that America can throw caution to the wind. For one, Massachusetts, where
more than 72 percent of all people have received at least one dose of the vaccine, leads every other state but Vermont on vaccination. Some states, particularly in the South and parts of the Midwest and West, still have one-dose rates below 50, 45, or even 40 percent. So an outbreak in Provincetown looks very different from one in Jackson, Mississippi.
There are also genuine unknowns about breakthrough cases. We still don’t know just how likely a vaccinated person is to get infected and transmit the virus to someone else. Nor do we know how many vaccinated people with breakthrough infections will suffer longer-term effects (colloquially known as
long Covid) that aren’t unique to the coronavirus but can be detrimental or even life-changing.
Nor is there enough research and data to draw final conclusions about the role of the delta variant, which spreads more easily and may evade the body’s immune response better than past versions of the virus. Future variants could complicate matters even further.
Still, the vaccines are very effective. The evidence continues to show the vaccines reduce the virus’s rate of spread, delta or not. Even when a vaccinated person is exposed to the coronavirus, the chances of hospitalization and death are near zero. In fact, experts said, the vast majority of breakthrough cases are likely to produce no symptoms whatsoever.
“This was a hard week,” Gandhi said. “But my conclusions are relatively unchanged.” She emphasized: “We need to get a lot more people vaccinated.”
What we know and don’t about breakthrough cases
The vaccines aren’t perfect. When the news broke last year that the Pfizer and Moderna vaccines reported more than 90 percent efficacy, that was certainly much better than the 50 percent or so efficacy rate that some experts and officials expected. But that’s not 100 percent. In fact, there’s no such thing as a perfect, 100-percent-effective vaccine for any illness.
Given that, some breakthrough cases were always expected, even before the delta variant.
Here’s what we know about breakthrough cases: They do happen, but the majority produce no symptoms and the vast majority cause no serious symptoms, hospitalizations, or deaths. According to a
review of the evidence by the CDC, data from the UK, Canada, and Israel shows the Pfizer/BioNTech vaccine is more than 90 percent effective against hospitalization or death, even with the delta variant. The CDC estimated unvaccinated people are eight times as likely to get the virus and experience disease symptoms, 25 times as likely to be hospitalized, and 24 times as likely to die, compared to people who are vaccinated.
Although not every state, nor the CDC, is attempting to track all reported breakthrough cases, the data we do have from about 25 states suggests the vast majority of serious cases, hospitalizations, and deaths still involve the unvaccinated. In
Virginia, for example, 99 percent of cases and 98 percent of hospitalizations and deaths this year, as of July 30, were among people who weren’t fully vaccinated. The total reported breakthrough case rate among vaccinated people was 0.034 percent. The hospitalization rate among reported breakthrough cases was 0.0032 percent. The breakthrough death rate was 0.0009 percent.
The
report from the Kaiser Family Foundation found similar numbers for other states that reported Covid-19 breakthrough data for at least a month.