Last spring, Israel's remarkably swift vaccination campaign was seen as a global model. Coronavirus infections plummeted, an electronic pass allowed the vaccinated to attend indoor concerts and sporting events, and distancing rules and mask mandates were eventually scrapped. Israel offered the world a hopeful glimpse of the way out of the pandemic. No longer. A fourth wave of infections is rapidly approaching the levels of Israel's worst days of the pandemic last winter. The daily rate of confirmed new virus cases has more than doubled in the last two weeks, making Israel a rising hot spot. Restrictions on gatherings and commercial and entertainment venues were reinstated this week, and the government is considering a new lockdown. Some experts fear that Israel's high rate of infections among early vaccine recipients may indicate a waning of the vaccine's protections over time. The vaccine may be less effective at preventing infection with the highly contagious Delta variant. The vast majority of Israel's older population had received two doses of the Pfizer-BioNTech vaccine by the end of February, and by now about 78 percent of the population 12 and older are fully vaccinated. Data published by Israel's Ministry of Health in late July suggested that the Pfizer shot was just 39 percent effective against preventing infection in the country in late June and early July, compared with 95 percent from January to early April.