Pfizer said on 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 cases of Covid, hospitalizations and deaths, according to Pfizer, which developed the injection with BioNTech.
The analysis used data collected between 17 January and 6 March, when the Pfizer vaccine was the only vaccine available in the country and when the most transmissible variant B.1.1.7 in the United Kingdom was the dominant strain.
“This is extremely important … for society,” said Bourla in an interview with CNBC’s “Squawk Box”. “Asymptomatic carriers and patients are those who mainly spread the disease. We were expecting something good in terms of symptomatic people, ”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 has no symptoms and never develops them. It is not the same as a pre-symptomatic patient who later develops the symptoms. It is estimated that at least 50% of transmission occurred in people who have no symptoms, according to a study published in JAMA in January.
The Israeli study means that the Pfizer vaccine can significantly reduce transmission.
“This clearly demonstrates the power of the COVID-19 vaccine to fight this virus and encourages us to continue our vaccination campaign even more intensely,” said Israeli Health Ministry director Yeheskel Levy in a press release. Our goal is to achieve even greater absorption 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, health professionals and people with comorbidities. In February, it was leading the world in vaccination, inoculating millions of its citizens against the virus.
In January, Pfizer and the Israeli Ministry of Health signed a collaboration agreement to monitor the impact of their vaccine in the real world.
Bourla also said on Thursday that the company is assessing the impact that a booster dose could 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.