Both vaccines require two doses spaced several weeks apart. But even one dose of either decreased the risk of infection by 80 percent two or more weeks later, researchers said.
“This study shows that our national vaccination efforts are working. The authorized mRNA COVID-19 vaccines provided early, substantial real-world protection against infection for our nation’s health care personnel, first responders, and other frontline essential workers,” Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention (CDC), said in a statement.
“These findings should offer hope to the millions of Americans receiving COVID-19 vaccines each day and to those who will have the opportunity to roll up their sleeves and get vaccinated in the weeks ahead. The authorized vaccines are the key tool that will help bring an end to this devastating pandemic,” she added.
The study was conducted by researchers at the CDC, a federal agency.
Some 3,950 healthcare workers, first responders, and other workers described as being essential and frontline jobs volunteered for the study. They were tested weekly for COVID-19 for 13 consecutive weeks, starting in mid-December 2020. Participants self-collected a nasal swab, which was tested in a laboratory in Wisconsin.
Among the participants, nearly 63 percent, or 2,479, received two vaccine doses. Another 12 percent received only one dose. The rest received no doses.
The participants live and work in Portland, Oregon; Temple, Texas; Salt Lake City, Utah; Duluth, Minnesota, Miami, Florida; and several locations in Arizona, including Phoenix.
The findings come after a string of studies indicated the vaccines are effective in preventing transmission of the CCP (Chinese Communist Party) virus, also known as SARS-CoV-2.
“It looks like both vaccines are very effective in at least what we know now as far as not only preventing disease, meaning getting bad COVID infection, but also maybe transmitting it, which is meant by infection where you might carry the virus,” Dr. Peter Gulick, an associate professor of Medicine at the College of Osteopathic Medicine at Michigan State University who is also an expert on infectious diseases, told The Epoch Times.
The research could lead to more relaxed restrictions on people who have gotten a COVID-19 vaccine. But those with weaker immune systems may see a lower efficacy than others. Gulick said he warns his patients who are immunosuppressed that when they get the vaccine, they should know they may be seeing a lower immunity level than others.
Researchers said the study was subject to at least three limitations, including the fact that specimens were self-collected, which combined with delays in shipping could reduce sensitivity of virus detection by testing. “if this disproportionately affected those who received the vaccine (e.g., because of possible vaccine attenuation of virus shedding), vaccine effectiveness would be overestimated,” they wrote.
The United States has fully vaccinated 52.6 million Americans against the CCP virus as of March 29, with another 41 million getting one of two doses.
Roughly one out of two Americans 65 years or older have been fully vaccinated.