Cases of COVID-19 are extremely rare among people who are fully vaccinated, according to a new data analysis by the Centers for Disease Control and Prevention.
Among more than 75 million fully vaccinated people in the US, just around 5,800 people reported a “breakthrough” infection, in which they became infected with the pandemic coronavirus despite being fully vaccinated.
The numbers suggest that breakthroughs occur at the teeny rate of less than 0.008 percent of fully vaccinated people—and that over 99.992 percent of those vaccinated have not contracted a SARS-CoV-2 infection.
The figures come from a nationwide database that the CDC set up to keep track of breakthrough infections and monitor for any concerning signs that the breakthroughs may be clustering by patient demographics, geographic location, time since vaccination, vaccine type, or vaccine lot number. The agency will also be keeping a close eye on any breakthrough infections that are caused by SARS-CoV-2 variants, some of which have been shown to knock back vaccine efficacy.
So far, the vaccines appear to be highly effective and working as expected, according to the CDC’s analysis—which the agency provided to Ars via email.
The vast majority of people in the US have been vaccinated with one of the mRNA vaccines, made by Moderna and Pfizer-BioNTech, which both had around 95 percent efficacy in Phase III clinical trials. Less than five percent of people in the US have received the Johnson & Johnson adenovirus-based vaccine, which had a slightly lower efficacy of 72 percent in the US.
The extraordinary calculation that 99.992 percent of vaccinated people have not contracted the virus may reflect that they all simply have not been exposed to the virus since being vaccinated. Also, there’s likely cases missed in reporting. Still, the data is a heartening sign.
“COVID-19 vaccines are effective and are a critical tool to bring the pandemic under control,” the agency said in its email. “To date, no unexpected patterns have been identified in case demographics or vaccine characteristics.”
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Many of the breakthroughs occurred in older people, who are well-known to be more vulnerable to COVID-19. More than 40 percent were in people ages 60 and above. However, the agency noted that there were breakthrough infections scattered through every age group that is currently eligible for vaccination.
“We see [breakthroughs] with all vaccines,” top infectious disease expert Anthony Fauci said in a press briefing earlier this week. “No vaccine is 100 percent efficacious or effective, which means that you will always see breakthrough infections regardless of the efficacy of your vaccine.”
Vaccines can fail in some people because of a variety of factors, including immune status, health status, age, and medications they’re on. There’s also the possibility that something went…