People who received their second dose of the Pfizer vaccine had a six- to 12-fold increase in the amount of antibodies produced to defend against the novel coronavirus, Sheba Medical Center in Tel Hashomer reported Monday.The results of preliminary research were based on 102 cases of medical personnel vaccinated at the hospital. They had more antibodies than people who were severely infected with the virus and recovered.“The results of the survey are in line with Pfizer’s experiment and even better than expected,” Prof. Gili Regev-Yochay, director of Sheba’s Infectious Disease Epidemiology Unit, said in a briefing Monday. “I expect that the survey results of the other employees participating will be similar. There is certainly reason for optimism.” The result of the data is that Israel should see a reduction in the outbreak of the coronavirus across the country as more people receive their second doses, she said.Two people did not develop antibodies, including one who is immunocompromised, Regev-Yochay said. There was no explanation for why the second person did not develop antibodies, and the hospital is investigating the matter, she said.At last count, 7,106 Sheba employees have been vaccinated with the first dose, or approximately 80% of all staff. Of those, 4,484 received their second dose as of Monday. Although the study only involved 102 cases, others were being evaluated, Regev-Yochay said.The study is specifically looking at immunoglobulin G (IgG) antibodies, which determine whether a patient has developed immunity. The study does not indicate how long the immunity will last or if a person who has antibodies can still carry the virus and infect others, Regev-Yochay said. However, she said it appeared to her that people who have been vaccinated will not shed the virus, meaning they will not pass it on to others.While people who were sick and recovered are not yet eligible to receive the Pfizer vaccine in Israel, if further research shows that the vaccine produces improved immunity, it is possible that they will be inoculated in a second phase, at least with the booster shot, Regev-Yochay said.