No, it's the other way around. Transmission is correlated with viral load. In the unvaccinated, high viral load leads to early self-observable symptoms. The vaccines are designed to suppress symptoms, so a vaccinated person can be infected and transmitting, without knowing they should be isolating. That's why the CDC recommends testing of vaccinated people after exposure, https://www.webmd.com/lung/news/20210729/cdc-reverses-guidan... (July 29, 2021)
> Even if they’re not showing symptoms, fully vaccinated people should “get tested 3-5 days after exposure to someone with suspected or confirmed COVID-19 and wear a mask in public indoor settings for 14 days after exposure or until they receive a negative test result,” ... “Our updated guidance recommends vaccinated people get tested upon exposure regardless of symptoms,” CDC Director Rochelle Walensky, MD, told The New York Times
In dense urban areas, many of the remaining "unvaccinated" are likely to be Covid survivors with natural immunity, which offers nasal/mucosal immunity in upper respiratory tract, which is not possible with intramuscular (arm deltoid injection) vaccines. A future nasal vaccine may offer such protection.
So many people talk about "vaccinated versus unvaccinated", but this dualistic framing is not conducive to scientifically accurate discussion. There are at least three groups of people to acknowledge:
A) vaccinated
B) immune via natural infection
C) immunologically naive (have never been exposed to the virus)
The A & B groups will have very similar characteristics in terms of individual risks and risks to others. Group C is what many people mean to refer to when they say "unvaccinated people spread COVID faster and with more frequency".
You're saying, confidently, that vaccinated people spread more COVID than un-vaccinated people? A bold strategy!
It's probably correct that lots of spread is happening because people feel OK, but that's because (especially with Delta) viral load typically peaks before symptoms show up[1]. That is, the most infectious period is probably before anyone feels symptoms, vaccinated or not. But of course the vaccines significantly reduce the chance of getting infected in the first place, and when you directly measure the secondary attack rate, instead of looking at a proxy like RT-PCR Ct, vaccination also seems to significantly lower that[2].
1. "Delta’s rise is fuelled by rampant spread from people who feel fine" https://www.nature.com/articles/d41586-021-02259-2
2. "Vaccine effectiveness against SARS-CoV-2 transmission and infections among household and other close contacts of confirmed cases, the Netherlands, February to May 2021" https://www.eurosurveillance.org/content/10.2807/1560-7917.E...
In practice, do they really? If you're vaccinated and catch COVID, you're probably fine, so you go about your life. If you're unvaccinated, you're more likely to get sick and thus stay home. You're also more likely to build up natural immunity. Seems to me like now that we know being vaccinated doesn't prevent transmission, we should want the anti-vaxxers to not get vaxxed, as we'll all reach herd immunity faster and they're less likely to get us sick.
The statement is true. If you're not vaccinated, and you get COVID, there's a non-zero chance that you'll be the source of someone else's breakthrough case.
This statement is also true: If you're vaccinated, and you get COVID, there's a non-zero chance that you'll be the source of someone else's breakthrough case.
So, the quote is kind of useless. The unvaccinated probably do spread COVID faster and with more frequency. So, the directionality of the quote is fine. But it reads like a boolean statement, which is incorrect. COVID is almost certainly endemic at this point. Vaccines clearly help, but it's incorrect to blame all of the mutations and spread on the unvaccinated.