Can You Spread COVID-19 Once Vaccinated? Data Not Yet Clear

Covid Spread

If you’re one of the 17% of Americans that have been fully vaccinated against SARS-CoV-2, you are probably feeling some level of relief. But the Centers for Disease Control and Prevention (CDC) warns not to throw your mask away just yet. 

On Monday, CDC director Dr. Rochelle P. Walensky made a comment in an interview with MSNBC’s Rachel Maddow that caused a stir of controversy in the scientific community.  

"Our data from the CDC today suggests, you know, that vaccinated people do not carry the virus, don`t get sick, and that it`s not just in the clinical trials but it`s also in real-world data,” Walensky said, creating the assumption that transmission from a vaccinated person was impossible.  

Yesterday the agency backpedaled on Walensky’s assertion, as this contradicted the CDC’s previous guidance regarding continued precautions even after being fully vaccinated. 

“Dr. Walensky spoke broadly during this interview,” an agency spokesman told The Times. “It’s possible that some people who are fully vaccinated could get Covid-19. The evidence isn’t clear whether they can spread the virus to others. We are continuing to evaluate the evidence.” 

Currently, studies are underway all around the world trying to determine whether or not vaccinated individuals can still spread the virus. While data is promising, it’s not yet ready to make that kind of positive claim. 

The vaccines currently approved for use against COVID-19 are about 90% effective. A real-world study in frontline workers reported that even after the first shot, individuals had 80% protection of not getting seriously ill but also preventing infection in the first place.  

“If you can’t get infected, you can’t infect anyone else, which means the vaccines can reduce transmission as well as the disease,” said Marm Kilpatrick, an infectious diseases researcher at the University of California, Santa Cruz, who was not involved in the study. 

So while data is trending towards suggesting it is harder for vaccinated people to become infected, Paul Duprex, director of the Center for Vaccine Research at the University of Pittsburgh warns, “Don’t think for one second that they cannot get infected.” 

Misinformation has abounded amidst this pandemic, which is why the scientific community wasn’t too pleased with Walensky’s generalized implication that vaccinated individuals don’t carry and therefore can’t spread the virus.  

“If Dr. Walensky had said most vaccinated people do not carry the virus, we would not be having this discussion,” said John Moore, a virologist at Weill Cornell Medicine in New York. 

“What we know is the vaccines are very substantially effective against infection — there’s more and more data on that — but nothing is 100 percent. It is an important public health message that needs to be gotten right.” 

While the real-world studies have been impressively positive, there has yet to be a vaccine that has provided complete 100% protection to every population. Variants have a way of sidestepping the immune system to infect. Additionally, those who are immunocompromised may experience a more blunted response to vaccination. 

Cases of infection after vaccination are considered “breakthrough” infections. These cases have been rare, compared to the numbers being vaccinated. Experts say they shouldn’t cause panic and are not a reason to avoid vaccination. The vaccines are extremely effective at preventing serious disease and complications that lead to hospitalization and death.  

Walensky closed her interview with a plea to Americans, “We know that these masks work, and we know that every individual should be taking it upon themselves to do what they can to protect themselves and to protect others. We are oh, so very close. 

“The president announced today, 90 percent of Americans will be eligible for a vaccine by April 19th. And 90 percent of Americans will be within five miles of a vaccination site by April 19th, extraordinary measures to get to where we need to be. So we’re just asking people to wear masks for just a bit longer.” 

There have been 30.6 million coronavirus cases diagnosed in the US since the first case in 2020, with 553,000 deaths. A recorded 56 million have been fully vaccinated with an average of 2.8 million people being vaccinated every day.  

“Vaccinated people should not be throwing away their masks at this point,” Moore said. “This pandemic is not over.” 

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