The COVID-19 vaccines in use now have been touted for how well they work—the Pfizer vaccine trials found its product to be 95 per cent effective in preventing COVID-19 infections after both shots and the Moderna 94.1 per cent effective after the same. And people are gradually becoming familiar and comfortable with how the mRNA technology that allowed these to be developed so quickly works. Scientists now have answers to many early questions about the vaccines.
But a question that there’s still no solid answer to is whether people who’ve been vaccinated can still carry the virus and potentially spread it to others.
The question arose as early as December, when Pfizer CEO Albert Bourla appeared on “Dateline NBC”Thursday night, alongside the CEOs of Moderna and Johnson & Johnson. "I think this is something that needs to be examined,” Bourla told Dateline. “We are not certain about that right now."
Data from studies that could give a better answer to that aren't in yet. “There is a theoretical risk that you could pass the virus on to others despite being vaccinated,” says Kirsten Hokeness, Ph.D., director of Bryant University’s new Center for Health and Behavioral Sciences.
But virus transmission by vaccinated people hopefully won’t be the case. “The goal of the vaccine is to create immunological memory in the body so that when you encounter the virus in the future, your immune system rapidly ramps up and attacks the virus very quickly before you get sick. Therefore, as long as the vaccine boasts a strong immunological response, it is likely that the virus will be stopped from replicating in your system pretty quickly,” Dr. Hokeness says.
That would limit your ability to spread it to others. “It can happen, but the risks would be far less than if you were not vaccinated,” she says, adding that “since the vaccine requires two doses, it may be that your ability to spread the virus would be greater if you only got one dose, but there is not data available yet that would suggest that that is the case."
Meanwhile, health experts are encouraging people who are vaccinated to act as if they could somehow pass virus they had acquired somewhere to other people—that means they need to keep masking and social distancing (and you do, too).
While vaccines are a vital tool in combating the pandemic, having them doesn’t mean everyone can safely return to “normal” right away. Or forever—it's not clear exactly how long post-vaccination immunity would last. That means keep doing what you’re doing, even after you receive the vaccine, until more research comes out.
The information in this story is accurate as of the publication date. While we are attempting to keep our content as up-to-date as possible, the situation surrounding the coronavirus pandemic continues to develop rapidly, so it’s possible that some information and recommendations may have changed since publishing. For any concerns and latest advice, visit the World Health Organisation. If you’re in the UK, the National Health Service can also provide useful information and support, while US users can contact the Center for Disease Control and Prevention. (edited)
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