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COVID vaccinated are NOT as likely to spread the virus as unvaccinated

I keep seeing the anti-vax claim that those who have received the COVID-19 vaccinated are just as likely to spread the virus as unvaccinated individuals. Another day, another myth from anti-vaxxers that must be debunked, because this is utterly ridiculous.

I know, it’s been debunked so many times, it seems fruitless to do it again, but it’s being used as one of the excuses to not get the vaccine. Among all of the dumb claims of the COVID-19 vaccine deniers, this is one of the dumbest.

This claim about those vaccinated against COVID-19 are as likely (or sometimes more likely) to spread the SARS-CoV-2 virus as unvaccinated is not supported by any scientific evidence. Yet, your local Twitter or Facebook anti-vaxxer loves to spread this inane trope, mainly because they can. And because people seem to believe any outlandish claim made about the vaccine.

COVID-19 vaccinated spread virus
Photo by Daniel Schludi on Unsplash

COVID-19 vaccinated and virus spread – what are the facts

1he origin of this story, I think it arose during Spring 2021 when the vaccines first came out. The CDC seem to indicate, at that time, that anyone who had been vaccinated against COVID-19 was now a super person – they wouldn’t spread the virus.

But most infectious disease, vaccine, and public health specialists were saying something completely different. And once again, the messaging war was messed up by our side.

I’m just a simple ancient dinosaur, yet I know that vaccines are not perfectly effective, and unless you love the Nirvana fallacy, that’s still pretty good. However, 95% effective means that 5% of vaccinated individuals may contract COVID-19, and spread the disease.

Furthermore, at that time the new Delta variant was showing up, and the vaccines had variable effectiveness against the new form of COVID-19.

And then there was a localized COVID-19 outbreak in Provincetown, Massachusetts—in which 74 percent of the 469 cases were in fully vaccinated individuals. This caused the CDC to admit that vaccinated people infected with the SARS-CoV-2 Delta variant can be just as contagious as unvaccinated people.

This is where the confusion started. People misinterpreted this outbreak as meaning that vaccinated people were just as likely to catch and pass along COVID-19 as unvaccinated. But that’s a misunderstanding of the mathematics of the situation.

Since more people were vaccinated than unvaccinated, it made it look like vaccinated individuals were more responsible for the outbreak. In fact, the incidence of positive COVID-19 was lower in vaccinated individuals compared to unvaccinated. Plus the severity of the disease was much lower in vaccinated individuals.

In the aftermath of the outbreak, news reports implied that it didn’t matter whether you were vaccinated or not. But this missed the single most important factor in spreading the coronavirus – to spread COVID-19, you have to have COVID-19.

And vaccinated people are far less likely to have the coronavirus – period, full stop. Let me repeat myself for those of you auditing the class in the back row – you can only spread the disease if you catch the disease, and if you are vaccinated, you have a much lower risk of catching the disease.

But if you want actual numbers, here’s something – recent data from New York City revealed that more than 96% of COVID-19 cases are among the unvaccinated. Only 0.33% of fully vaccinated New Yorkers have been diagnosed with COVID-19. In other words, the unvaccinated are over 290X more likely to catch COVID-19 compared to vaccinated individuals.

If that doesn’t bust the myth that those who have been vaccinated against COVID-19 are just as likely or more likely than unvaccinated people, I don’t know what else will.

Based on the New York City data, it’s clear that those who are vaccinated are very unlikely to catch the disease, a minuscule risk. Moreover, even if one person in a group of vaccinated people catches the disease, there is almost no risk of passing it to another vaccinated person.

However, in a group of unvaccinated people, the risk that one of them is infected with COVID-19 is quite high. And the risk that they spread it to other unvaccinated people is astronomical.

According to an article published in The Atlantic:

This is exactly why vaccine mandates are so important—and why going to events that exclude unvaccinated people is much, much safer than those that are open to all. Everyone knows that the vaccines help protect each individual who gets their shots. But when more people get vaccinated, this helps keep everyone else (including children and others ineligible for vaccination) safe as well.

woman holding sign
Photo by cottonbro on

My thoughts

I am a scientist, so I don’t consider absolutes as part of my lexicon about medicine. Vaccines are the best protection we have against COVID-19, but they are not perfect. Effectiveness is not 100%, it wanes over time, and it may have issues with some future variant.

You cannot boost your immune system against COVID-19 with any miracle product out there unless it’s a vaccine.

Yes, vaccinated people do experience breakthrough infections. However, based on all of the evidence, vaccinated people have an overwhelmingly lower risk of contracting the disease than those who are unvaccinated. That’s a scientific fact, not my opinion.

Vaccinated people are not spreading the disease, they just aren’t. Yes, a tiny percentage do catch the disease, and they might spread it to unvaccinated people. But that’s a far lower rate than unvaccinated people who catch the disease and spread it to other unvaccinated people.

I know that this is a forlorn wish of mine – but the trope that vaccinated people spread the COVID-19 virus as much as vaccinated is false, false, false.

Michael Simpson

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