| The news about breakthrough infections can seem alarming. It shouldn't. The very first data from the large randomized vaccine trials that arrived last fall included breakthrough infections, or cases of Covid-19 among people who have been fully immunized. There were eight cases in the trial of the Pfizer-BioNTech vaccine out of almost 22,000 people immunized. That compared with 162 cases in the similar-sized group that got the placebo. With Covid vaccines out in the real world, and 165 million Americans fully immunized, some breakthrough cases are to be expected. What's important is that people who catch Covid despite being vaccinated are much less likely to be hospitalized or die than unvaccinated people. And as the vaccinated population increases, the number of cases in that population will necessarily increase as well. On Monday, the Biden administration said 70% of U.S. adults had received at least one dose. The math isn't intuitive. It's easily overlooked in an atmosphere of deep mistrust and deliberate misinformation about the Covid vaccines. Without context, reports about breakthrough cases, or knowing someone who got Covid even though she was vaccinated, can trigger anxiety about whether the vaccines work.  Scientists are studying breakthrough infections reported on Cape Cod in Massachusetts. Photographer: Craig F. Walker/Boston Globe What's missing, though, is a sense of how many cases might have occurred absent vaccination—like the data from the control arm of a clinical trial. It's not an easy thing to discern outside of formal studies, but some comparisons provide context: Massachusetts, with about 6.9 million residents and 69% vaccinated, added about 9,000 Covid cases in July, and recorded 87 deaths. Missouri, with about 6.1 million residents and 46% vaccinated, added 57,000 cases in the same period, and 371 deaths. Scientists are still investigating how long vaccine protection lasts and to what extent the delta variant or other mutations blunt the shots' effectiveness. New evidence on that front is important. The recent outbreak on Cape Cod showed that immunized people could spread the delta variant and prompted U.S. authorities to reverse earlier advice that vaccinated people can safely unmask in many settings. Centers for Disease Control and Prevention data show that of more than 163 million people vaccinated, 6,587 were hospitalized or died with breakthrough infections, a rate of 0.004%. (The tally includes asymptomatic cases where hospitalization or death were unrelated to Covid.) Breakthrough cases seem salient now. We're hearing about them more because they didn't exist before people were vaccinated. But what should be more concerning is how many people haven't gotten inoculations shown to protect against most sickness and death.—John Tozzi | 
Post a Comment