Israeli Study Finds Pfizer Vaccine Only 64 Percent Effective Against Delta Variant

Israel's health ministry said Monday that the Pfizer/BioNtech vaccine appears to be just 64 percent effective against preventing symptoms from the fast-spreading Delta COVID-19 variant, but remains highly effective at preventing serious illness and hospitalizations.

According to data released by the ministry, the vaccine's ability to prevent symptomatic COVID-19 has dropped by roughly 30 percent over the past two months.

Previous studies in May showed the Pfizer vaccine to be over 94 percent effective in preventing COVID-19, while new data shows that number dropping to just 64 percent from June to July, The Times of Israel reported.

However, the study found that the vaccine remains highly effective against preventing serious symptoms and hospitalization associated with the coronavirus. In May, that figure stood at 98.2 percent, while it was 93 percent in June.

The Delta variant, also known as B.1.617.2, is more contagious than other strains of COVID-19 and is thought to be responsible for 90 percent of new cases in Israel over the past two weeks, The Times reported. The country's health ministry said Monday that 369 people had been diagnosed with coronavirus that day, bringing the total number of active cases in the country to 2,766.

In response to a rise in new cases, the Israeli government instructed the health ministry to promote two medical studies regarding the need for a third COVID-19 vaccine shot. According to Israeli Prime Minister Naftali Bennett's office, the studies will seek to "evaluate the efficacy of the vaccine and the rate at which it wears off over time."

Israel Pfizer
Israel's Ministry of Health said Monday that the Pfizer/BioNtech vaccine appears to be less effective against the fast-spreading Delta variant. Here, an Israeli medical worker prepares a dose of the Pfizer/BioNTech Covid-19 vaccine on July 5, 2021, in Tel Aviv. JACK GUEZ/AFP/Getty Images

Meanwhile, in the U.S., health care experts and President Joe Biden have sounded the alarm on the Delta variant, warning that the disease will likely spread quickly among unvaccinated Americans.

According to the Centers for Disease Control and Prevention (CDC), an estimated 25 percent of all COVID-19 cases in the U.S. are now a result of the Delta variant. Data collected from the agency found that the states with the highest proportions of the Delta variant include Missouri, Colorado and New Jersey.

Ahead of the 4th of July weekend, COVID-19 cases were up across nearly half of the country, USA Today reported. Health care experts warned that large gatherings and celebrations from the holiday will likely result in a wave of new infections, particularly in states with low vaccination rates.

Nonetheless, a survey released Sunday by ABC News/The Washington Post, found that among unvaccinated Americans, 73 percent believe the risks of the Delta variant are being over exaggerated by the government.

To combat vaccine hesitancy, White House COVID response coordinator Jeff Zients announced the recent deployment of COVID-19 surge response teams to contain the virus and help increase vaccination rates across the nation.

According to the CDC, 157.3 million Americans, or 47.4 percent of the U.S. population, are fully vaccinated against COVID-19. A total of 67.1 percent of Americans have received at least one dose of the shot.

Newsweek contacted Pfizer for additional comment on the Israeli study, but it declined as the data was unpublished.