In the world’s most detailed data on how people feel after a Pfizer COVID vaccine, Israel found that less than 0.3 percent had side effects that they thought were significant enough to report to doctors.
The Department of Health officials who released the study believe it will provide peace of mind to many around the world who would like to get a picture of the vaccine’s impact. They wrote that side effects are “similar in frequency and nature to the symptoms reported after other vaccines are given to the population.”
They also emphasized that side effects are normally “mild” and “pass quickly.”
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After the first shot, 6,575 of 2,768,200 Israelis sought medical attention for side effects, which is 0.24%. The figure after the second shot was 0.26% – 3,592 from 1,377,827 recipients.
The last number indicates that while the second shot is known to make some people feel bad, it rarely escalates into formal medical complaints.
Israelis at a Clalit Health Service-run vaccination center in Petah Tikva, Jan. 27, 2021. (Miriam Alster / Flash90)
Doctors responded enthusiastically to the data. “People around the world should feel comfortable,” Yoav Yehezkeli, a physician and public health expert at Tel Aviv University who was not involved in the study, told The Times of Israel.
Few complaints ended in hospital admission – an average of 17 patients per million after the first admission and three patients per million after the second admission. Yehezkeli said doctors expected a few patients to experience significant side effects, and he personally treated a patient who had partial paralysis of the facial nerve after her second injection, but said the statistics show the incidence is low. His patient recovered.
It was the first major real-world analysis of side effects, many times the number involved in Pfizer’s clinical studies. The findings, which are accurate through Jan. 27, are in line with the expectations health organizations around the world have based on research data.
The U.S. Centers for Disease Control and Prevention noted before the vaccine became available that it can cause side effects that are normally “mild to moderate,” while “a small number of people had serious side effects.”
The CDC expected the main side effects to be local pain or broader symptoms such as chills and headache, which “may feel like flu symptoms.” That was what the Israeli data found.
A doctor in a protective suit and mask is holding a syringe and vaccine. (oshcherban via iStock by Getty Images)
The vast majority of the complaints concerned local pain in the arm or people who generally did not feel well. Arm pain was responsible for 50% of the complaints with the first shot and 22% of the complaints with the second shot. About 41% of first-shot complaints and 73% of second-shot complainers reported feeling generally unwell.
There were also some more unusual side effects.
Neurological symptoms were reported by 287 vaccinees with the first dose and 96 vaccinees with the second dose. There were 165 reports of allergic reactions, including anaphylaxis, after the first shot and 47 after the second shot. Other unusual side effects were reported by 60 and 19 people after the first and second injection, respectively.
Israel’s statistics should be considered reliable because the country’s health system includes “active surveillance” for side effects, Yehezkeli said. “These are important numbers because many people in Israel have already been vaccinated and the healthcare system is very organized with methods for reporting side effects,” he said.
“I am a practicing physician and whenever I report a patient with a fever, for example, who has recently been vaccinated, the computer system generates an alert and asks me to report this as an adverse reaction. This is what I call active surveillance. “
