Israeli Study: Recovered COVID Patients With One Vaccine Have Protection Similar to Three Doses

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A health worker prepares a dose of the Pfizer coronavirus vaccine in Jerusalem, on Thursday.
A health worker prepares a dose of the Pfizer coronavirus vaccine in Jerusalem, on Thursday.Credit: Ohad Zwigenberg

People who recovered from the coronavirus and then received one dose of the COVID-19 vaccine are protected from the virus at levels similar to those who were never infected and received three doses, a study conducted by Israel’s Gertner Institute has found.

As a result of the findings, the Health Ministry’s epidemic advisory panel is recommending that patients who have recovered from the virus receive only one dose of the vaccine, barring exceptional circumstances. The panel further recommended that for the time being, such people need not get vaccinated at all to qualify for a Green Pass permitting them into public places restricted due to the pandemic.

The study was based on data on infection and serious illness in Israel between July 11 and August 27 among those who had been infected during the second wave (nine to 10 months ago) and/or during the third wave (six to seven months ago) and who had received one vaccine dose. The figures were compared to data on patients who had recovered from the virus but had not been vaccinated.

Using data from the second wave, which peaked in September and October of last year, the researchers found that among 96,845 recovered patients who were not vaccinated, 880 had been reinfected with COVID, two of them becoming seriously ill. The data was compared to statistics regarding those who had recovered from the virus and who had received a single vaccine dose following their recovery. Of 96,882 patients fitting that description, 246 people were reinfected, of which three cases were serious.

During the third wave, which peaked last January, when the British alpha variant had become dominant, the researchers found that among 184,969 recovered patients who had not been vaccinated, 796 of them (0.43 percent) were reinfected, nine in serious condition. Among the 55,424 recovered patients who received one vaccine dose after their recovery, only 89 (0.16 percent) were reinfected and there were no cases of serious illness.

A vaccine station in Daliat al-Carmel in August.Credit: Adi Ofer

The researchers also looked at data from August after Israel began administering a third dose of the vaccine, initially to those 60 and over. The study examined Israelis who received the third dose between August 10 and 27 and found that only 0.06 percent, or 543 people among 876,784 individuals vaccinated, were infected, including 23 who became seriously ill.

The study did not include those who recovered from the first wave of the pandemic or in the current fourth wave. Health Ministry guidelines require three months to elapse after recovery before the vaccine is administrated, so it is too soon for those infected during the fourth wave to receive the dose.

The third dose has resulted in a marked reduction in infections among those who have received it during the current wave.

“With regard to recovered patients and the current wave, data has not yet been presented. On the other hand, based on the fantastic level of protection against hospitalization provided by recovery since the beginning of the pandemic, we are cautiously optimistic that the phenomenon will continue in the current wave,” said Dr. Lion Poles, a member of the Health Ministry advisory committee on epidemics.

“Of course, we need to monitor hospitalization data for the coming months. Nevertheless, it’s important to stress that avoiding being vaccinated – on the assumption that getting infected and recovering will provide a ‘natural’ vaccine to the person’s who been infected – is a very dangerous phenomenon. It’s gambling with your life and health, and risks disability and other mid- and long-term damage,” Poles said.

“Recently young and healthy people who were not vaccinated have died of the coronavirus, and we are also seeing young unvaccinated people in critical condition and hooked up to ECMO machines,” Poles said, referring to a specialized heart-lung medical device. “The first and second doses are very effective in preventing illness involving hospitalization and death, and as time passes following the vaccination, the booster shot is similarly also very effective.”

The new research also used data from 4.5 million Israelis who had been vaccinated with two doses between January and March of this year to model how the effect of the vaccine wanes over time. Of the 1.46 million people who had two doses in January, there have so far been 22,000 cases of infection and 805 serious cases.

Among the 1.39 million who had two doses in February, there were 29,000 cases of infection but only 183 cases of serious illness from the coronavirus. Among the 1.42 million people who had two doses in March, there were 26,000 cases of infection and only 126 serious cases.

The study also did some follow-up on 876,000 patients aged 60 and over who received their third dose beginning on August 10. They found only 543 cases of infection and 23 cases of serious illness.

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