Some people who received the Johnson & Johnson shot experienced fainting or dizziness afterward, which the CDC now says was actually due to anxiety and not an issue with the vaccine. J&J is the only vaccine ​​​​​​ that calls for one dose.

A new study from the public health agency reveals that similar temporary reactions have been reported for years in connection to other vaccines. According to Huffington Post, people can become so anxious at the thought of getting an injection that they show physical manifestations of anxiety. The authors collected data from clinics in five states—California, Colorado, Georgia, Iowa, and North Carolina—from a two-day period, April 7 to 9.

A total of 64 people felt faint, dizzy, nauseated, or threw up after receiving the J&J vaccine, while others felt their heart rate speeding up or chest pain, among other side effects. No one was found to be in critical condition after taking the dose. The CDC report discovered that around a quarter of the people who experienced symptoms also have a history of reacting to vaccines.

These cases were not related to the group of people who dealt with blood clots after getting the J&J vaccine, which spanned at least 17 people. At the end of April, the U.S. lifted the recommended pause on J&J after a panel of advisers said it was safe to resume the single-shot immunization.