Since the approval of the vaccines against SARS-CoV-2, multiple countries have been proceeding with mass vaccination campaigns with varying levels of success. Already in March 2021, more than 50% of the Israeli population was vaccinated (1). During that time, the country was in the middle of an infection wave that peaked in January with 981 new daily confirmed cases per million (7-day rolling average). This decreased to 34 cases in April and further to 1 in June. The trend has changed towards the end of the month (1). The upward movement culminated in the record of 1255 cases in September leading to such headlines as “Number of COVID patients on ventilators hits highest level since March” in The Times of Israel (2). This begs a question of whether the vaccines do not work as intended or maybe even are the sole cause behind the surge.

It has been proposed by minor but active groups on social media that the vaccines may be directly responsible by causing a SARS-CoV-2 infection, via an antibody-dependent enhancement (ADE) mechanism or by weakening the recipient’s immune system. However, none of the approved vaccines in Israel contain the whole SARS-CoV-2 virus (3). It is thus impossible for the infection to occur through the vaccines. Alternatively, this could be explained as a result of the ADE, enhancement of infection via the help of weakly neutralizing antibodies (4). During an initial infection, our bodies produce antibodies specific to a pathogen. In case the antibodies are not capable of neutralizing a virus they had been generated against, they may help the virus instead. This may happen in a subsequent infection with the pathogen as it was observed with Dengue viruses. Nevertheless, this has not been observed in relevant models with SARS-CoV-2 infection or vaccination (5). Furthermore, the hypothesis that the vaccine weakens a recipient’s immune system would have an observable effect. Namely, the vaccinated population would have a higher rate of hospitalization and death, which was not the case. All of the above is contrary to studies in which the vaccine’s effectiveness has been calculated (6, 7).

The high effectiveness of the vaccine has been confirmed in a large observational study from January till April 2021 (7). Subsequent domination of the new and more infectious (8) Delta variant may be partially responsible for the uptick in the overall infections but it does not seem to fully explain the situation in the country as the effectiveness of the vaccine in recently inoculated Israeli dropped only mildly for the Delta variant (9). New studies from the USA and Qatar shed light on this issue. It has been shown that the effectiveness of the vaccines against infections wanes over time significantly (from 90% right after full vaccination to 50% after 5 months or to approx. 20% depending on the study) independently from the age of the patient and the variant (6, 10). Interestingly, the vaccine effectiveness against hospital admissions did not change during the observation period, which is in line with the lower number of COVID-19 patients (per million) in hospitals in Israel (1).