The Pfizer vaccine has prevented 94 per cent of recipients in Israel from getting symptoms in a huge peer-reviewed study of 1.2 million people.
The experiment took place between December 20 and February 1 - a period when the British mutant strain of Covid was rampant, making the vaccine's performance all the more impressive.
The paper published in the New England Journal of Medicine marks the latest victory for Israel whose world-beating vaccine rollout has given Pfizer jabs to more than 50 per cent of its 9 million population - more than a third have received both doses.
The country ended draconian lockdown restrictions earlier this month and started to reopen its economy over the weekend with concert halls, gyms, hotels and theatres welcoming vaccine passport holders.
The 'green pass' is valid for six months from the time of full vaccination (two doses) or for those who have recovered from Covid-19 and are immune.
Up to 500 passport holders can attend outdoor cultural venues, while crowds of 300 are permitted indoors at theatres, museums and cinemas.
Restaurants and cafes remain restricted to takeaway service and schools kids are back in class only in areas where infection rates are low.
The scheme is being closely watched abroad, with Boris Johnson saying that Britain was looking at the idea of 'Covid-status certification' while adding that there were 'many concerns surrounding exclusion, discrimination and privacy'.
Despite Israel's cautious unlocking, academics have been buoyed by Wednesday's study and it will raise Prime Minister Benjamin Netanyahu's hopes of cruising to election victory on March 23 after the successful vaccination drive.
'The fact that the vaccines worked so well in the real world... really does suggest that if the nations of the world can find the will, we now have the means to end Covid-19 forever,' said Ben Neuman, a virologist from Texas A&M University who was not involved in the research.
The study took around 1.2 million Israelis and divided them into equal groups of vaccinated and unvaccinated.
Each vaccinated participant was matched to an unvaccinated 'control' person of similar age, sex, geographic, medical and other characteristics.
Lead author Noam Barda, head of epidemiology and research at the Clalit Research Institute, told AFP the matching process was highly robust.
An elderly Ultra-Orthodox Jewish man from a particular neighbourhood with a particular set of comorbidities and flu vaccination history would be matched for another person fitting that precise profile, for example.
The researchers then recorded outcomes at days 14-20 after the first of the two doses and day seven or more after the second.
The efficacy against symptomatic infections was 57 percent between 14-20 days after the first dose, but rose to 94 percent seven days after the second dose - very close to the 95 percent achieved during Phase 3 clinical trials.
People who received second doses were also highly protected against hospitalisation and death - though the precise numbers here are less significant and had a wider statistical range because of the relatively lower number of cases.
The study also found people who received their second dose had a 92 percent lower chance of getting any form of infection at all compared to those who were unvaccinated.
While this finding was considered encouraging, the researchers and outside experts said it needs more confirming evidence.
That's because the participants weren't being systematically tested at regular intervals; rather, they were getting a test when they wanted one.
The authors attempted to correct for this with statistical methods but the result is still likely imperfect.
'Unless you are testing everyone all the time, this will miss some infections,' said Natalie Dean, a biostatistician at the University of Florida.
She added she was certain there was a strong protective benefit, but 'nailing down this number more precisely will require specialised study designs with frequent testing.'
More than three million Israelis are now eligible for the Green Pass having either had both doses of the Pfizer jab or been infected by Covid already.
Israel, which has one of the world's most sophisticated medical data systems, secured a substantial stock of the Pfizer/BioNTech vaccine by paying above market price and by striking a data-sharing deal with the drug giant.
Shopping malls and stores with street access re-opened to the general public on Sunday, with certain limitations on crowd size.
But gyms, swimming pools, hotels and some cultural facilities are re-opening only to those who have been fully vaccinated and obtained the so-called green pass.
Lifting weights at a gym in Petah Tikva near Tel Aviv late Saturday, Mr Netanyahu insisted Israel was moving ahead 'with caution', while imploring 'everyone to get vaccinated'.
Standing at the entrance of a posh Tel Aviv gym, 90-year-old Ora Davidovicz said she 'couldn't wait' to go swimming.
'It's been almost a year since I went to the pool,' she said. 'I've been counting the days. All I have to do is put on my swim suit,' she said, before heading in.
Tom John, a muscular 33-year-old, said he'd been training at home for months but felt safe being back at the gym with the protection systems in place.
'Everyone here has a green badge,' he said, surveying the gym.
At the family owned Katalina shoe store in central Tel Aviv, Mordechai Nazarian said his business had been closed for eight of the last 12 months, with 'little openings here and there' as Israel lifted restrictions between lockdowns.
'We hope this one is the right one,' he said.
Israel has given more does people per-100 people than any other country in the world. As of February 25, 88.77 people out of 100 have had at least one dose.
By comparison, 27.34 people per 100 have been given at least one dose in Britain, which is still the third highest rate in the world.
At the Third Ear record store in Tel Aviv, 32-year-old Itay Shimon said he hadn't been in a record store in many months, but was enjoying just browsing the aisles.
Describing himself as a vaccine supporter, he also voiced caution about compelling people to get the jab.
'We cannot force those who don't want it to do it,' he said.
Despite the successful vaccination Israel's government has approved a night-time curfew from Thursday until Sunday to prevent the spread of the coronavirus over the Purim holiday.
The Prime Minister's Office and Health Ministry said a curfew from 8.30pm until 5am would be in force starting Purim eve.
Purim, a Jewish holiday traditionally marked with carnivals and gatherings, begins Thursday at sunset.
The holiday lockdown prohibits any large gatherings of more than 10 people indoors at concerts, parades or parties typical of the holiday's observances.
Israel reopened its economy last week after a nearly two-month lockdown, the country's third since the start of the pandemic. But recent days have seen a slight uptick in new infections.
It has one of the highest immunisation rates per capita, with over 4.5 million of its citizens having received at least one dose of the coronavirus vaccine.
The Health Ministry has recorded more than 763,000 cases and 5,660 Covid deaths since the pandemic started.
This article has been adapted from its original source.
