Pfizer vaccine shows 94% effectiveness against asymptomatic transmission of COVID
Pfizer's vaccine is successful in preventing not only symptomatic COVID-19, but also asymptomatic disease according to new real-world data, Israel's Ministry of Health and Pfizer/BioNTech announced Thursday.
The announcement included a key statistic related to an alarming way the virus can spread -- via people who are asymptomatic, who may not even know they're contagious. The Pfizer vaccine is so far 94% effective at preventing this type of infection, Israel's Ministry of Health reports -- encouraging news that the vaccine could help slow silent transmission.
The Pfizer clinical trials were designed to measure how well their two-dose vaccine worked to stop symptomatic cases of the disease -- cases where people knew they had the virus, including severe cases leading to hospitalization or death. Israel's most recent announcement citesÂ the Pfizer vaccineÂ as 97% effective at preventing these sorts of cases -- which roughly matches the 95% efficacy Pfizer noted in its trials.
Israel's latest data, yet to be peer reviewed, was collected two weeks after administration of the secondÂ vaccine dose, reinforcing the idea that both doses are needed to achieve the full efficacy they report. And those who did not receive the vaccine were up to 44 times more likely to develop symptomatic disease, and 29 times more likely to die from COVID-19.
"For the people that have already been vaccinated, it's another reason why it's so important that we've already rolled up our sleeves and received the vaccine," said Dr. Todd Ellerin, director of Infectious Diseases at South Shore Health. "And for those who are vaccine hesitant, hopefully data like that shows that these vaccines are unbelievably effective at not just preventing severe disease, but also markedly reducing infection. And if you can reduce infection, you will reduce transmission."