August 1, 2021 — by Ingu Yun, MD
We’re hearing nothing but bad news stemming from the recent outbreak of Covid cases in Provincetown, the majority among fully-vaccinated people. “The war has changed,” says the Center for Disease Control and Prevention, as they issued their report on the Provincetown outbreak (or, as they say, “a town in Barnstable County”).
On the surface, the numbers look frightening. Nearly 1000 Covid cases have been reported stemming from a two-week period in Provincetown when thousands of people from all over visited the town. Of those cases, 75% were fully-vaccinated. 7 were hospitalized. And the viral load of the infected vaccinated was as high as or higher than the viral load of the unvaccinated. The CDC, equating viral load with infectivity, is now recommending that everyone wear masks — vaccinated and unvaccinated alike — in public indoor settings.
The problem with this messaging is that it increases the fear in vaccinated folks, when that fear is unfounded. And it sends a message to the unvaccinated that the vaccines aren’t working, which is completely wrong.
Here’s the proper way to interpret the numbers coming out or Provincetown.
First of all, this CDC report is not a controlled study. This is a report from a period of time when 60,000 mostly gay men descended on a resort town to pack themselves into poorly-ventilated bars and clubs every day for several days. Virtually no one was wearing a face mask. A couple of clubs were requiring proof of vaccination for entry, but most were not. It rained a lot those two weeks, driving the hordes indoors even more than usual. How do I know all this? I was there! (I spent 99% of my public time outdoors, and wore a mask the few times I had to go indoors.)
This was an exceptional circumstance in an exceptional location.
Now, let’s look at the numbers. While Barnstable County overall has a 69% vaccination rate, Provincetown itself is 95% vaccinated. The demographics of the visitors — predominantly liberal gay men, a minority of liberal lesbians, and a further minority of liberal straight folks — is also likely to be close to 95% vaccinated. This was certainly true at the guest house where I stayed, and the one indoor show I attended, where everyone was vaccinated. Unfortunately too many people assumed that it was 100% all the time.
There were 60,000 visitors to Provincetown during the period in question. That would translate to 57,000 vaccinated folks and 3,000 unvaccinated folks.
How many tested positive for Covid? Current reports say about 750 vaccinated folks and 250 unvaccinated.
This means that 750/57000 vaccinated folks tested positive, or 1.3%. 250/3000 unvaccinated folks tested positive, or 8.3%. Being vaccinated gave you a more than 6-fold protection against Covid than being unvaccinated. This is similar to the protection figures published in the early spring of 2021, before the Delta variant had any impact in this country.
What about the hospitalizations? 6 vaccinated cases were hospitalized, out of 750 cases. That’s 0.8% of cases. Historically, 5% of Covid cases have resulted in hospitalization in the US. That’s a nine-fold improvement!
The Provincetown numbers tell me that the vaccines are working. That this outbreak happened in Provincetown during its busiest two weeks of the summer tells me that when you pack as many mask-less people as possible into poorly-ventilated rooms for long stretches of time, and then throw unvaccinated folks into the mix, even the fully-vaccinated can’t escape the risk. But this was always the case, and this will always be the case. Delta has not changed this.
There are two ways the outbreak might have been minimized. One might have been if all indoor spaces required masks. Another, possibly better way, would have been for all indoor spaces to require proof of vaccination. (Of course, I’m guessing here. There’s no way to know for sure, until the proper epidemiologic studies are done.) Since mid-July Provincetown has reinstated a mask mandate, and many businesses have begun to require proof of vaccination.
The Delta variant has turned Covid into a pandemic of the unvaccinated. It’s difficult finding data separating out Covid numbers for the vaccinated and the unvaccinated. The Virginia Department of Health does a good job of this, and they show that vaccinated folks are still doing about as well as they were at the most recent trough in June.
What about the possible increased transmissibility of the Delta variant by vaccinated people? Well, first of all, no one knows if this is actually true. Even the CDC cautions about the interpretation of their data in the very same report that triggers the warning:
The findings in this report are subject to at least four limitations. First, data from this report are insufficient to draw conclusions about the effectiveness of COVID-19 vaccines against SARS-CoV-2, including the Delta variant, during this outbreak. As population-level vaccination coverage increases, vaccinated persons are likely to represent a larger proportion of COVID-19 cases. Second, asymptomatic breakthrough infections might be underrepresented because of detection bias. Third, demographics of cases likely reflect those of attendees at the public gatherings, as events were marketed to adult male participants; further study is underway to identify other population characteristics among cases, such as additional demographic characteristics and underlying health conditions including immunocompromising conditions. … Finally, Ct values obtained with SARS-CoV-2 qualitative RT-PCR diagnostic tests might provide a crude correlation to the amount of virus present in a sample and can also be affected by factors other than viral load. … However, microbiological studies are required to confirm these findings.
And even if transmissibility is increased, the risk is primarily for the unvaccinated, and remains about the same as pre-Delta for the vaccinated. In other words, the CDC recommendation for everyone to wear masks indoors is to protect the unvaccinated. Unfortunately the CDC is silent on whether masks are necessary if everyone in a group is vaccinated, but their previous publications have suggested this.
The bottom line … if you are vaccinated you are still well-protected, especially if you are among other vaccinated people. The Provincetown experience doesn’t change that. If you’re not vaccinated … well, that’s a different story.