Pfizer said Thursday that its Covid-19 vaccine blocked 94% of asymptomatic infections in an Israeli study, a result that CEO Albert Bourla called “extremely important.”
The study, which measured results two weeks after the second dose, also found that the vaccine was at least 97% effective against symptomatic Covid cases, hospitalizations and deaths, according to Pfizer, which developed the injection with BioNTech.
The analysis used data collected between January 17 and March 6, when Pfizer’s vaccine was the only available injection in the country and when the most transmissible UK B.1.1.7 variant was the dominant strain.
“This is extremely important … to society,” Bourla said in an interview with CNBC’s “Squawk Box.” “Asymptomatic carriers and patients are the ones who spread the disease mainly. We expected something good in terms of symptomatic,” he said, adding that the company did not expect such a “high number” of asymptomatic cases.
An asymptomatic person is someone who has Covid-19 but does not have any symptoms and never develops it. It is not the same as a presymptomatic patient who later develops symptoms. It is estimated that at least 50% of transmission is due to people who do not have symptoms, according to a JAMA study published in January.
The Israeli study means that the Pfizer vaccine could significantly reduce transmission.
“This clearly demonstrates the power of the COVID-19 vaccine to combat this virus and encourages us to continue even more intensively with our vaccination campaign,” Israel Health Ministry Director Yeheskel Levy said in a press release. Our goal is to achieve even greater acceptance in people of all ages, which gives us hope to regain normal economic and social function in the not too distant future. “
Israel launched its national vaccination campaign in December prioritizing people aged 60 and over, healthcare workers and people with comorbid illnesses. In February, it was leading the world in vaccinations, vaccinating millions of its citizens against the virus.
In January, Pfizer and the Israel Ministry of Health signed a collaboration agreement to monitor the impact of their vaccine in the real world.
Bourla also said Thursday that the company is evaluating the impact that a booster dose may have on the virus, particularly the B.1.351 strain in South Africa, which he said “appears to be the most difficult.”
“We already have very good protection with two doses,” he said.