Symptomatic Covid cases drop by 94% after Pfizer vaccine - the latest study explained

Tuesday, 16th February 2021, 10:39 am
Updated Tuesday, 16th February 2021, 10:40 am
Symptomatic cases of Covid-19 are dropping by 94 per cent after two doses of the Pfizer/BioNTech vaccine, according to a new study (Photo: JACK GUEZ/AFP via Getty Images)

According to the largest study of real-world data from Israel, symptomatic cases of Covid-19 have dropped by 94 per cent after two doses of the Pfizer/BioNTech vaccine.

The research was conducted by Clalit, which is the largest healthcare provider in Israel, and it shows that the Pfizer/BioNTech vaccine is equally effective across all age groups.

The preliminary results show a 94 per cent drop in symptomatic cases, and a 92 per cent drop in serious cases.

‘Clear that the Pfizer vaccine is extremely effective’

Professor Ran Balicer, founding director of the Clalit Research Institute, said: “It’s now unequivocally clear that Pfzier’s coronavirus vaccine is extremely effective in real life a week after the second dose, just as was found in the clinic trials.

“Furthermore, the trends we identify indicate that continued follow-up for additional weeks after the second dose will significantly increase the measures efficacy of the vaccine.

“In fact, in a preliminary examination, we identify even higher efficacy for the prevention of symptomatic and severe disease among the vaccinated after 14 days.”

Israeli scientists have been put under pressure to share peer reviewed studies with other countries, but Professor Balicer has warned that the new study was still based on preliminary data.

Speaking to Sky News, he said: “We have no manuscript that we can share at this time.”

Clalit is expected to publish its results in full soon.

How was the study carried out

Clalit said that the study was carried out with a team from Harvard University. Researchers analysed 1.2 million people, 600,000 of which had received both doses of the Pfizer/BioNTech jab, and 600,000 of those who had not.

The study was constructed so that each vaccinated person was tested against an unvaccinated person who had a similar profile, such as their general health, where they live, their risk level of infection and risk of becoming seriously ill.

In a press statement, Clalit said: “The creation of the control group was done dynamically so that people were deducted and moved between groups if their immunisation status changed over time.

“This form of calculation, which produces a complete resemblance in time to the place and personal characteristics between the vaccinated and non-vaccinated at any given moment, allows to fully normalise the impact of events that happens in parallel - such as the effects of quarantine, and changing vaccine contraindications.”