One dose of either Pfizer/BioNTech or AstraZeneca vaccines can reduce the risk of CCP virus transmission by up to a half, a new study has found. A preprint of the study (pdf) by Public Health England (PHE) said that those who received one dose of a vaccine at least 21 days before being tested positive have a 40–50 percent lower chance of transmitting it within the same household than those who were unvaccinated. The study also said the data indicated that the reduction in transmission can be detected at 14 days after vaccination. PHE analysed data from 365,447 households with one person that has tested positive for COVID-19, the disease caused by the CCP (Chinese Communist Party) virus, between Jan. 4 and Feb. 28 (index case). All index cases were aged 16 and over, and most of them are under 60 years old. Among them, most unvaccinated index cases were under 40—the age …