As the world looks to Israel, reports emerge that Pfizer vaccine may be less effective than previously thought 

The efficacy of the Pfizer vaccine may not be as high as reported by Israeli studies, some experts say, pointing to the fact that the original data was collected while Israelis were social distancing, wearing masks and under a nationwide lockdown.

Now, with the economy being reopened and children returning to school, doctors are casting doubt on the reported effectiveness of the vaccine. 

Prof. Eran Segal of the Weizmann Institute said that the “impressive numbers” of the vaccine’s efficacy could dwindle if social behavior changes, increasing a vaccinated person's chances of becoming infected.

According to a study on the Pfizer injection among the Israeli population, the vaccine is 95% effective in preventing infection and 99% effective in avoiding serious illness and death. The study did not take into account social distancing, mask wearing and lockdowns.

Those numbers are clearly unsupported by a report that 12 residents from a Beersheva nursing home tested positive for the coronavirus one month after receiving both doses of the vaccine. According to Channel 12, a nurse who tested positive for COVID-19 infected a dozen fully vaccinated residents out of the 30 he came in contact with – well over one-third of his patients.

The residents were vaccinated a month prior to the outbreak. The Channel 12 report added that the residents who tested positive were asymptomatic and that the tests were performed routinely after the nurse tested positive.

“The Ministry of Health was instructed to do two tests to make sure that the results were reliable, but from what we understand only those who are negative were tested again,” the daughter of one of the residents told the TV station. “It sounds strange to us because the number of infected does not match the data we know about vaccines.” 

She said her father and other residents have since been moved to a geriatric center for coronavirus patients in another town.

Such an outbreak – after vaccination – is concerning to the Geriatrics Division of the Ministry of Health, which is investigating whether mutations of the coronavirus have spread. But the Health Ministry maintains that, in any case, the level of morbidity and death in nursing homes has dropped dramatically since the vaccinations began.

Former Director General of the Ministry of Health, Dr. Gabi Barbash, noted that studies on the vaccine’s effectiveness were conducted before the mutations existed.

Prof. Nadav Davidovitch, chairman of the Association of Public Health Physicians, said Israelis have not reached herd immunity and must continue to wear masks, because “vaccinated people may still infect others and endanger them.”

Since Dec. 20, some 87% of Israeli adults have already been vaccinated with at least one dose of the Pfizer injection.