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Israeli Study Offers First Real-World Glimpse of COVID-19 Vaccines in Action

Posted on by Dr. Francis Collins

COVID-19 Update: Large scale clinical trial
Credit: Getty Images/Hispanolistic

There are many reasons to be excited about the three COVID-19 vaccines that are now getting into arms across the United States. At the top of the list is their extremely high level of safety and protection against SARS-CoV-2, the coronavirus that causes COVID-19. Of course, those data come from clinical trials that were rigorously conducted under optimal research conditions. One might wonder how well those impressive clinical trial results will translate to the real world.

A new study published in the New England Journal of Medicine [1] offers an early answer for the Pfizer/BioNTech vaccine. The Pfizer product is an mRNA vaccine that was found in a large clinical trial to be up to 95 percent effective in preventing COVID-19, leading to its Emergency Use Authorization last December.

The new data, which come from Israel, are really encouraging. Based on a detailed analysis of nearly 600,000 people vaccinated in that nation, a research team led by Ran Balicer, The Clalit Research Institute, Tel Aviv, found that the risk of symptomatic COVID-19 infection dropped by 94 percent a week after individuals had received both doses of the Pfizer vaccine. That’s essentially the same very high level of protection that was seen in the data gathered in the earlier U.S. clinical trial.

The study also found that just a single shot of the two-dose vaccine led to a 57 percent drop in the incidence of symptomatic COVID-19 infections and a 62 percent decline in the risk of severe illness after two to three weeks. Note, however, that the protection clearly got better after folks received the second dose. While it’s too soon to say how many lives were saved in Israel thanks to full vaccination, the early data not surprisingly suggest a substantial reduction in mortality.

Israel, which is about as large as New Jersey with a population of around 9 million, currently has the world’s highest COVID-19 vaccination rate. In addition to its relatively small size, Israel also has a national health system and one of the world’s largest integrated health record databases, making it a natural choice to see how well one of the new vaccines was working in the real world.

The study took place from December 20, 2020, the start of Israel’s first vaccination drive, through February 1, 2021. This also coincided with Israel’s third and largest wave of COVID-19 infections and illness. During this same period, the B.1.1.7 variant, which was first detected in the United Kingdom, gradually became Israel’s dominant strain. That’s notable because the U.K. variant spreads from person-to-person more readily and may be associated with an increased risk of death compared with other variants [2].

Balicer and his colleagues reviewed data on 596,618 fully vaccinated individuals, ages 16 and older. A little less than one third—about 170,000—of the people studied were over age 60. To see how well the vaccine worked, the researchers carefully matched each of the vaccinated individuals in the study to an unvaccinated person with similar demographics as well as risks of infection, severe illness, and other important health attributes.

The results showed that the vaccine works remarkably well. In fact, the researchers determined that the Pfizer/BioNTech vaccine is similarly effective—94 percent to 96 percent—across adults in different age groups. It also appears that the vaccine works about equally well for individuals age 70 and older as it does for younger people.

So far, more than 92 million total vaccine doses have been administered in the U.S. With the Janssen COVID-19 vaccine (also called the Johnson & Johnson vaccine) now coming online, that number will rise even faster. For those of you who haven’t had the opportunity just yet, these latest findings should come as added encouragement to roll up your sleeve for any one of the authorized vaccines as soon as your invitation arrives.


[1] BNT162b2 mRNA Covid-19 Vaccine in a Nationwide Mass Vaccination Setting. Dagan N, Barda N, Kepten E, Miron O, Perchik S, Katz MA, Hernán MA, Lipsitch M, Reis B, Balicer RD. N Engl J Med. 2021 Feb 24.

[2] Emerging SARS-CoV-2 Variants. Centers for Disease Control and Prevention.


COVID-19 Research (NIH)

Clalit Research Institute (Tel Aviv, Israel)

Ran Balicer (Clalit Research Institute)


  • Steve White says:

    I am interested in discovering why the disease caused by SARS-CoV2 is called “Covid 19” . I admit I do not know much about virology but it seems to me diseases are either named by perceived place of origin or some defining trait and “Covid 19” appears to be a completely anomalous name. Can anyone help with this? Thanks in advance.

    • Julio Casoy says:

      COrona VIrus induced Disease occurring in 2019 CO + VI + D + 19

      • Steve White says:

        Thanks for the info, I knew what the acronym stood for but why use any acronym, is that a normal naming convention?

        • Sue Miles says:

          I read somewhere that there has been trouble with previous names implying images and causing fears … they wanted to do it differently this time.

  • Trudi Trahan-upchan says:

    I Believe because it is a corona “Sars” virus mutation that first developed in 2019 – corona virus is not new – this is a new mutation.

  • Jonathan M. Gordon, M.D. says:

    It apparently stands for Coronavirus disease 2019. That is easier for people and the press to deal with than SARS 2 Coronavirus Disease

  • Debbie Burgess says:

    Excellent info. Thank you for sharing results on different variants than the original test results from the US study.

    • Faina says:

      I have a severe reaction to my first Pfizer vaccine: in a few days, I had a burning feeling behind my right knee cap. It was on – off. Then the burning spot moved to the side of the knee. The entire area around my knee was swollen like a bagel. I started taking Benadryl. And used an ice pack to reduce inflammation. For 3 days I took Advil… It’s getting better now, but I’m extremely scared to go have my 2nd Pfizer vaccine. Please advice !

  • Mark Russell says:

    If these Statistics are real, isn’t it time that we Vaccinate all of the 3,300,000 School Teachers, so that they can back to Teaching the 53,000,000 Students in the U.S? I feel that it is a National Emergency not to Vaccinate our Educators. The argument is that the Students don’t spread the Virus. That argument is only a Smoke Screen—-It is the 2% of the Teachers that will infect the other 98% of the Teachers.

  • Deb Kitt says:

    Is there any information about the vaccine’s side effects? It is so hard to get reliable information on this. Just curious as to any severe side effects or coincidental deaths. There are some people who believe that the death of a loved one shortly after a vaccination was due to the actual vaccination. I know you don’t like to speculate or seriously look at this side of things, but I do think it is important to note. I expect the incidence is quite low, but still would like to see some data.

  • IC says:

    Thanks for sharing this information. It is a very useful …

  • JH says:

    I do wish to see real adverse event reporting data and not just endless platitudes about safety.

  • Steve White says:

    So, there seems to be no doubt the Pfizer vaccine is very highly effective against the two types we have here, and it is good to see that, with B.1.1.7 becoming dominant in the US, but what do we know about B.1353 and P1? Those scare me more.

    B1351 is reported to be reinfecting many people in South Africa, and we know many vaccines are not very effective, if at all effective, against it.

    P1 has reinfected a very, very large number of people in Manaus who got sick in the first wave last year – so it seems certain it can do that here, if the vaccines we use do not stop it.

    I do not know why we did not fly our vaccines into Manaus and do a study there when the outbreak started, or some comparable field test. So far, I see purely test tube testing which is being presented in entirely opposite ways – does anyone have any info. on this? It is a very important question.

  • Paula R. says:

    Was there a study on how the covid recovered patients that received only 1 dose of the pfizer did as far as being effective? I had covid in June and had horrible side effects with the first dose and on the fence n getting the second dose. American doctors are just using a canned response saying the CDC recommends everyone getting 2 doses whereas Israel only gave 1 dose to covid recovered patients.

    • Mike R. says:

      What is the source of the assertion that “Israel only gave 1 dose to cover recovered patients”?

    • Steve White says:

      Paula R.: You are probably aware of a study, I do not know any details but saw a headling, indicating ONE dose of Pfizer vaccine is sufficient for those who had Covid already. I do not know ANY details at all but you can probably find the study by doing some searches. I would hold off, for a very long time I was in your position.

  • Thomas K. says:

    I am an 82 yr. old male who is in the “maintenance” phase of chemotherapy for acute lymphoblastic leukemia. (Strong chemo. treatment both in & out of hospital, 4/20 through 10/20.) I had my first Moderna vaccination on 1/2/21 and my second one on 2/1/21. Had a covid antibody test on 3/9/21 and it came back negative for antibodies. I’ve been quite restricted from all outside contact from the beginning of my leukemia treatment. Is there some way to establish immunity from covid without enduring the extreme isolation through the end of my leukemia maintenance period October 2022?

    • Steve White says:

      Do you know which type of antibody test you took? I do not fully understand the details, but the vaccines give you S antibodies, S for Spike, but SOME of the tests used to detect antibodies are looking at N antibodies and will come back negative for a person who was never infected, but still has a good reaction to the vaccines and has plenty of S antibodies.
      Remember, most of the antibody tests were created to see if a person had been infected in the past, not to check if the vaccines worked on that person, because the vaccines did not even exist yet, the antibody tests came first.
      So I was told by people who researched this – they were in the Pfizer vaccine tests- one even worked at a Pfizer testing facility. .

      Please make sure of what antibody test you got, if it was for N antibodies you need to get an S antibody test. I forget what search terms I used but there is a chart online which tells you which antibodies the tests check for. I was in the Pfizer study of their vaccine and was given shots but not told if they were real vaccine or placebo, I took a test at Quest DIagnostics, and it came back negative, but then I found out it tested for N antibodies and did not tell me anything.

      Some other lab did use an S type test. I will try to get the name and put it up here.

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