Scientists determined whether vaccinated people can be carriers of coronavirus

U.S. scientists conducted a unique experiment. During the COVID-19 outbreak in one prison, they used a PCR test to assess the presence of viral particles in the nasopharynx of inmates in shared cells. Unvaccinated inmates tested positive 93 percent of the time, while vaccinated inmates tested positive 70 percent of the time. This suggests that the vaccinated, though to a lesser extent, also carry the infection.

COVID-19 vaccines are effective in preventing severe illness and death, but the extent to which vaccinated people contribute to the spread of coronavirus infection has not been fully known until now.

In the late summer of 2021, when the most aggressive strain of delta arrived in the United States, researchers from the Centers for Disease Control and Prevention, supported by the U.S. Federal Bureau of Prisons, took nasopharyngeal swabs for several weeks from inmates at a Texas state prison, which at the time had 74 percent of its inmates infected.

They chose those who lived in two large shared cells as their subjects for observation. Of the 95 participants included in the study, 78 were fully vaccinated, two were partially vaccinated, and 15 were unvaccinated. Most of those vaccinated received the Pfizer vaccine, 73%, a smaller proportion received Moderna 18%, and even fewer received Johnson & Johnson 9%.

Samples collected were analyzed by reverse transcription polymerase chain reaction (RT-PCR) and full-genome sequencing of the virus was performed. The results obtained by PCR were compared with the duration of virus survival in cell culture.