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COVID-19 vaccines are losing their effectiveness against infection over time and might become less protective in preventing severe illness and death, the nation’s top health officials said Wednesday. These new medical findings, announced at a White House press briefing, are spurring the campaign to boost Americans’ immunity by administering a third dose of the vaccine. “You don’t want to find yourself behind, playing catch up,” said Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases. “Better to stay ahead of it than chasing after it.” (Krieger, 8/18)

Three studies published Wednesday by the Centers for Disease Control and Prevention show that protection against the coronavirus given by vaccines declined in the midsummer months when the more contagious delta variant rose to dominance in the United States. At the same time, protection against hospitalization was strong for weeks after vaccination, indicating the shots will generate immune fighters that stave off the worst effects of the virus and its current variations. (Guarino and McGinley, 8/18)

A trio of new real-world US studies examine the ongoing effectiveness of two doses of the Pfizer/BioNTech and Moderna mRNA vaccines against COVID-19, one finding significantly ebbing efficacy against infection in nursing home residents and two showing sustained protection against coronavirus-related hospitalizations but declining coverage against new adult cases. (Van Beusekom, 8/18)

The data behind health officials’ plan to offer COVID-19 vaccine booster shots to fully vaccinated Americans showed waning effectiveness against infection for both authorized mRNA jabs. The studies, published by the Centers for Disease Control and Prevention (CDC) on Wednesday and discussed during a White House COVID-19 response briefing, involved data collected in New York, U.S. nursing homes and hospitals. The study out of New York, which focused on new COVID-19 cases and hospitalizations among adults between May 3 and July 25, found the age-adjusted vaccine effectiveness against diagnoses declined from 92% to 80% over time. (Hein, 8/18)

Covid-19 vaccines are less effective against the delta variant, according to results in the U.K. from one of the largest real-world studies into the efficacy of the shots. Pfizer Inc. and BioNTech SE’s messenger RNA vaccine lost effectiveness in the first 90 days after full vaccination, though that shot and the one made by AstraZeneca Plc still staved off a majority of Covid infections. When vaccinated people did get infected with delta, they were shown to have similar levels of virus in their bodies as those who hadn’t had shots. This suggests that vaccinating large portions of a population might not protect those who don’t get inoculated, casting doubt on the idea of achieving herd immunity. (Kresge, 8/19)

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 on the international charts. (Kershner, 8/18)

Early data from Israel suggests a booster shot of Pfizer Inc.’s Covid-19 vaccine can significantly improve immunity in those aged 60 and above, as the U.S. and other countries plan additional doses to increase protection against the highly infectious Delta variant. Israel was one of the first countries late last month to authorize a third Pfizer dose for the elderly who were fully vaccinated with the recommended two shots, after indications that vaccine protection against severe illness has waned. (Lieber, 8/18)

When Pfizer representatives met with senior U.S. government health officials on July 12, they laid out why they thought booster shots would soon be necessary in the United States. Data from Israel showed the vaccine’s effectiveness waned over time, especially in older and immunocompromised people. But officials from the Centers for Disease Control and Prevention disagreed, saying their own data showed something quite different, according to four people with direct knowledge of the meeting who spoke on the condition of anonymity. (Abutaleb and Sun, 8/18)