A new study just published in Science, which analyzed the records of nearly 800,000 US veterans of all ages found that the three main Covid-19 vaccines experienced ‘dramatic’ drops in efficacy over six months.

Prior to this study, three reports of the U.S. Centers for Disease Control (CDC) in August 2021 demonstrated protection against infection had declined in mid-summer as the Delta variant rose to dominance; protection against hospitalization and death remained high.

This phenomenon has been most comprehensively monitored in Israel, where high levels of transmission of the Delta variant led to a resurgent outbreak in mid-June 2021, despite a successful nationwide campaign to vaccinate the population.

This new study examined SARS-CoV-2 infection and deaths by vaccination status in 780,225 Veterans during the period February 1, 2021 to October 1, 2021, encompassing the emergence and dominance of the Delta variant in the U.S.

Between early March and September, as the Delta variant rapidly became the dominant strain worldwide, the ability of Moderna’s two-dose vaccine to prevent infections dropped from 89% – 58%, Pfizer’s went from 87% – 45%, and J&J’s single-dose vaccine went from 86% to just 13%.

The vaccines’ ability to prevent death in older Americans remained somewhat robust over the same period, according to the report.

Among veterans 65 and older who were inoculated with the Moderna vaccine, those who developed a so-called breakthrough infection were 76% less likely to die of COVID-19 compared with unvaccinated veterans of the same age.

Older veterans who got the Pfizer-BioNTech vaccine and subsequently experienced a breakthrough infection were 70% less likely to die than were their unvaccinated peers.

And when older vets who got a single jab of the J&J vaccine suffered a breakthrough infection, they were 52% less likely to die than their peers who didn’t get any shots.