“It’s hard to crystal-ball this,” said Dr. Richard Zane, chief innovation officer with UCHealth, a nonprofit health care system headquartered in Colorado.
According to the Centers for Disease Control and Prevention (CDC), a person who is vaccinated against COVID-19 can still be infected with or “carry” the virus that causes COVID-19 while not feeling sick or having symptoms. Experts call this “asymptomatic infection.”
The CDC says the vaccine is effective at keeping you from getting sick, but scientists are still learning how well it prevents people from spreading the virus.
“The short answer is there’s some emerging evidence that vaccines protect you from not just getting sick but also getting infected and spreading COVID. And it’s scientifically intuitive that that should be the case,” said Zane. “What we really need is more information, and this information is more difficult to study than whether people get sick or not after getting vaccinated.”
Zane said the evidence indicating the vaccine does help prevent the spread of COVID-19 includes studies out of Israel.
One study conducted by the Israeli Health Ministry and Pfizer Inc. found that the vaccine reduced infection, including asymptomatic cases, by 89.4% and in symptomatic cases, by 93.7%.
Zane said a true indication of whether the vaccine helps prevent the spread of the virus will come from studying those who live or work with people who have been vaccinated.
“We need to compare them to those who are not close to someone who’s been vaccinated and then we also have to measure people who have been vaccinated and see if there is virus in their nose, essentially,” said Zane.
Zane said asymptomatic infection sets COVID-19 apart from other viruses and makes it difficult to measure.