Among the nearly one million Israelis vaccinated against Covid-19 so far, some 240 Israelis have been diagnosed with the virus days after getting the shot, The Times of Israel reported on Thursday quoting Channel 13 News.
The figure underscores the need for individuals to continue to protect themselves for weeks after being inoculated, as the body takes time to develop effective antibodies against the SARS-CoV-2 virus, which causes Covid-19.
The Pfizer vaccine is not made with the coronavirus itself, meaning that there is no chance anyone could catch it from the shots. Instead, the vaccine contains a piece of genetic code that trains the immune system to recognize the spiked protein on the surface of the virus and create antibodies to attack if it encounters the real thing.
But this process takes time, and studies of the vaccine so far have shown immunity to the virus rises only some 8-10 days after the first injection — and then only to around 50 percent effectiveness.
This is why the second dose of the vaccine, given 21 days after the first, is critical: It strengthens the immune system's response to the virus, bringing it to 95% effectiveness and ensuring that immunity lasts. This level of immunity is only reached about a week after the second dose — or 28 days after the first.
Anyone who is infected a few days before getting the vaccine's first dose or in the weeks before full effectiveness is reached is still in danger of developing symptoms. (Even when the vaccine reaches its top potential, there remains a 5% chance of this.)
Another matter to note is that studies have not yet determined whether the vaccine allows a person to carry the disease and spread it, without getting sick: It is possible that while one's body would be largely protected from the virus after vaccination, mucous layers in the nasal passages, beyond the reach of antibodies, could still harbor multiplying virus particles.
While these would not harm the carrier — as any virus that enters deeper into the body would swiftly be destroyed by the trained immune system — they could still be expelled through the nose and mouth and infect others.
The vast majority of Israelis who have received the vaccine have reported no issues since getting the shot. Around one in a thousand people have reported suffering mild side effects, with only a few dozen seeking medical attention following the shot, figures published Wednesday showed.
The most common side effects reported were weakness, dizziness and fever, with 319 combined cases, the ministry said. Five also reported suffering diarrhea. Another 293 people reported localized symptoms where the injection was administered such as pain, restriction of movement, swelling and redness.
Fourteen people said they had allergic reactions such as itching and swelling of the tongue and throat.
Additionally, 26 people suffered what the ministry described as "neurological symptoms," with 19 complaining of a tingly sensation in their arm.
The ministry noted that only 51 people (0.008%) of those who reported suffering any side effects said they sought medical attention for their symptoms.
According to the Kan public broadcaster, there have been four cases where people in Israel have died shortly after receiving the vaccination, but three of the four were deemed by the Health Ministry, as well as by both family members and doctors, to have been unrelated to the shots. The fourth case, an 88-year-old man who had serious preexisting health problems, is currently being investigated.