It had already shown very good results in clinical trials and now it was put to the test in the real world. The Pfizer-BioNTech vaccine proved to be 94% effective in a study done with more than half a million fully vaccinated Israelis. While still preliminary, the findings show the effectiveness of the vaccine in a mass vaccination campaign.

Israel’s vaccination campaign is being closely watched by other countries because of its record speed. The country started vaccinating in December 2020 amid the third wave of the pandemic and full hospitals. By the end of January, 33% of the population had already received the first dose of the vaccine and 19% had received their second dose, and Israel is a clear leader in the global vaccination race.

Israel is mainly using the Pfizer-BioNTech vaccine, which is made using messenger RNA, or mRNA, a technology that delivers genetic code to cells to train them to fight the virus without actually changing anything about the body’s genes. The proteins made with the mRNA instructions activate the immune system, teaching it to see the spike protein as foreign and develop antibodies and other immunity weapons with which to fight it.

The Pfizer-BioNTech vaccine had already been tested with positive results, but there were still some concerns that it wouldn’t be as effective outside of a clinical trial. Those fears were proven to be unfounded. The vaccine was found to be approximately 95% effective, preventing mild and severe forms of Covid-19 without any serious side effects. The trial included 44,000 volunteers, half getting the vaccine and half a placebo.

Effective against variants

As the virus started to mutate and different variants emerged, Pfizer performed a study with the University of Texas and found the vaccine appeared to be effective against the mutations that emerged in the UK and South Africa. The researchers took blood from 20 patients who had been given the vaccine and found their immune system could take out the new mutation. It’s still too early to draw any definite conclusions, but for the most part, the vaccine seems to be effective against the variants tested so far.

But the big reason for optimism is how effective the vaccine is against the original strain. Israel’s largest healthcare provider, Clalit, found that after both doses of the vaccine, people are 94% less likely to have symptomatic COVID-19 infections and 92% fewer cases of severe illness due to the novel coronavirus.

“It shows unequivocally that Pfizer’s coronavirus vaccine is extremely effective in the real world a week after the second dose, just as it was found to be in the clinical study,” Ran Balicer, Clalit’s chief innovation officer, told Reuters. The data indicate that the vaccine is even more effective two weeks or more after the second shot, he added.

The study, which hasn’t been peer-reviewed yet, analyzed data on 1.2 million people, about half of whom had received the vaccine. The researchers compared patients who received the vaccine with similar individuals who hadn’t. Researchers are already seeing signs that the vaccines are helping to curb infections and hospitalizations among in Israel. There was a 41% drop in confirmed COVID-19 infections in people aged 60 and older, and a 31% drop in hospitalizations from mid-January to early February. Close to 90% of people aged 60 and older in the country have received their first dose.