The CDC released new COVID-19 guidelines for fully vaccinated people earlier last week, advising vaccinated people to continue to respect health measures meant to prevent transmission when in public or when gathering. The CDC does say that people who have received both shots can meet indoors without masks beginning two weeks after the second jab. That’s when full immunity kicks in, assuming the drug elicits the desired immune response.
But first-gen coronavirus vaccines aren’t designed to block COVID-19 transmission. Instead, they’re supposed to prevent severe COVID-19 and deaths. Also, the COVID-19 vaccines have various efficacy ratings, meaning that they won’t provide perfect, 100% protection. That’s why there’s a theoretical risk that fully vaccinated people can still get infected. They might pass the virus to others as well, even if they don’t develop symptoms themselves.
That might sound confusing, but The Guardian put together an animation that explains exactly what happens inside the body after vaccination and why you still need to wear a face mask.
When the coronavirus vaccine reaches cells after the first shot, the immune system reacts immediately to the new threat. A normal immune system treats the vaccine as an intruder and develops antibodies to neutralize it. Side-effects that appear after a vaccination show that the body is already working to protect itself.
Those antibodies will travel the entire body and they’ll kill the actual virus if a vaccinated individual catches SARS-CoV-2. As The Guardian’s animation explains, the coronavirus can still colonize the cells inside the nasal cavity, where it would multiply and attempt to spread to the lungs. Some antibodies might be present in the upper airways, but scientists are still studying whether they’re present in large enough numbers to prevent the virus from infecting cells in the nose.
The virus will try to descend to the lungs, where it would do the most damage. A bigger army of antibodies would face the virus there, essentially blocking it from infecting lung cells. Unable to multiply, the virus will die off and the person would not develop symptoms. The nose remains the problem since vaccinated people could still carry the virus for long enough to spread it to others, whether it’s via coughing, sneezing, or just talking and breathing. That’s why face masks and social distancing are still advised after vaccination.
Also, that’s why the CDC isn’t ready to endorse what some states are doing. Face mask mandates have been lifted in various places, despite the CDC’s warnings. The agency’s new guideline update only includes one specific scenario where face masks can be removed. That’s indoor gatherings where everyone who is present has been fully vaccinated for at least two weeks.
Just as vaccination campaigns are ramping up, researchers are producing more research on vaccine effectiveness. The latest discovery comes from Israel, which partnered with Pfizer and BioNTech to analyze data from vaccinated individuals. They found that the drug can significantly reduce asymptomatic transmission in vaccinated people. This would mean the vaccine offers protection against infection — and also that immunized people aren’t a risk of infection to others. More data is needed on the subject before health officials can make new recommendations. Israel already said that it won’t follow the CDC’s lead by loosening mask restrictions for indoor meetings between fully vaccinated people.
Even if the vaccine blocks coronavirus infections, vaccinated people would still need masks. Vaccines aren’t 100% effective. A tiny percentage of immunized people will get infected and develop a more severe version of the illness. That’s where masks and social distancing would prevent them from infecting other people.
The more people are vaccinated, the lower the risk of infection. Even if the vaccines can’t block infection entirely, they can still kill the virus rapidly after infection. As a result, vaccines would help the immune system effectively kill the virus before it’s able to do any real damage.
The Guardian’s animation is available at this link.
