At a time when most countries have vaccinated less than one percent of their population against COVID-19, with a few stuck in single figures, Israel has passed 20 percent. Now, the first studies of the effects show that the program is working, dramatically slashing rates of infection and hospital admissions. However, early results suggest that – for the Pfizer/BioNtech vaccine at least – it really is necessary to vaccinate twice, as the protection from a single injection is lower than has been hoped.
As nations around the world competed to secure early access to vaccines, the Israeli Government scored pole position. It convinced Pfizer that its relatively small population, restricted borders, and well-established capacity to organize and track its citizens would allow it to report the effects of mass vaccination more quickly than anywhere else. Manufacturers saw the benefit of such data, both from a publicity perspective – assuming the product worked – and for helping larger states plan their own programs. The fact Israel's rate of infection was above average, although not exceptional, also made it a prime testing ground. The reward was priority delivery of enough Pfizer/BioNtech doses to vaccinate its entire population, while the rest of the world struggles to get a fraction of what they need.
Keeping the promise to provide early results, the Israeli health ministry and Maccabi Healthcare Services have released separate reports on infection rates among the vaccinated.
According to Maccabi, only 31 people out of 163,000 fully vaccinated customers became infected 7-16 days following their second shot. A control group of similar ages had over 6,500 infections in the same period. The two groups are not perfectly comparable – those who get vaccinated may be more concerned about COVID-19 and likely to take other precautions, for example. Nevertheless, it takes a lot to explain away a 200-fold difference in infection rates. Maccabi told the Times of Israel the vaccine was 92 percent effective, only slightly below the 95 percent reported in clinical trials. That's particularly impressive since the Maccabi sample was much older on average than Pfizer's test population.
The health ministry's sample is larger, and the results almost as good. Within a week of their second vaccination, 317 people out of 715,425 tested positive for SARS-CoV-2, a rate of 0.04 percent. It's harder for clinical trials to measure rare events like hospitalizations and deaths than infections, so it's particularly important that Israel reported just 16 hospital cases among the vaccinated, or 0.002 percent.
As well as being consistent with the clinical trials, the results match those from Los Angeles County, where sickness rates have plunged among firefighters since vaccinations began.
Israel's total infection rates have been falling since January 14, but prior to the release of this data, it was impossible to tell if this reflected the success of the vaccination program or other interventions. Many nations have achieved similar falls recently thanks to increased mask-wearing or stay-at-home orders.
However, the Israeli data is less positive for the benefits of a single Pfizer/BioNtech dose, possibly explaining why Israel's national infection rate kept climbing even after a larger proportion received their first round. At the time of writing, there are 404 critically ill patients in Israeli hospitals who got their first vaccine dose prior to testing positive. This potentially conflicts with the clinical trial data, which showed infection rates flatlining even before the second round was administered.
If this observation is confirmed, it will have important implications for health authorities wrestling with the question of whether it is better to use limited resources on prioritizing vaccinating populations fully, or a larger group once.