Oct. 20 (UPI) -- Just over half of all people in the United States are "extremely, moderately or slightly likely" to take a COVID-19 vaccine that meets the Food and Drug Administration's minimum threshold for effectiveness, an analysis published Tuesday by JAMA Network Open found.
The public's willingness to receive an injection intended to prevent infection with the new coronavirus is influenced by the characteristics of the vaccine, as well as the politics surrounding its development, the data showed.
The nearly 1,000 adults surveyed in the analysis indicated that they would be 16% more likely to take a vaccine if it is found to be 90% effective at preventing infection, the researchers said.
The FDA has said that it will approve any vaccine against COVID-19 that is at least 50% effective at preventing infection or reducing disease severity, which is roughly the protection offered by the annual flu shot, according to the U.S. Centers for Disease Control and Prevention.
"Unsurprisingly, vaccine efficacy is an important driver of public willingness to vaccinate," study co-author Douglas L. Kriner told UPI.
"If the first [approved] vaccine or vaccines are at or near this minimum threshold, public health officials may have to do more to overcome public skepticism and convince Americans of the broad public health benefits," said Kriner, director of the Institute of Politics and Global Affairs at Cornell University.
For their study, Kriner and his colleagues surveyed 1,971 adults from across the United States in July, when COVID-19 numbers were rising in many parts of the country.
An increase in vaccine effectiveness from 50% to 70% raised the likelihood respondents would take the shot by about 7%, the data showed.
A vaccine that was 90% effective increased respondents' willingness to receive it by about 16%.
In addition to the shot's effectiveness, politics also played a role in the public's interest in any vaccine against COVID-19, Kriner and his colleagues found.
For example, respondents to the survey were 13% less likely to accept a vaccine made in China than one made in the United States.
However, endorsements from the CDC and World Health Organization increased respondents' willingness to receive the vaccine by up to 10%, the researchers said.
"Our findings speak to the dangers of politicizing the vaccine -- endorsements form political leaders resulted in significantly lower levels of public willingness to vaccinate than endorsements from public health officials at the CDC or WHO," Kriner said.
"Politicization risks undermining all of the financial and intellectual capital invested thus far in this unprecedented effort," he said.