Bloomberg reports that herd immunity against SARS-CoV-2 may not be possible, due to the rise of new variants such as Delta. The duration of natural immunity is uncertain – and it is not clear whether it will protect people against future variants. The Infectious Diseases Society of America has estimated that Delta has pushed the threshold for herd immunity to over 80 percent – and the world is far from achieving that level of vaccination, especially in low- and middle-income countries. William Hanage, an epidemiologist and expert in communicable disease dynamics at Harvard’s T.H. Chan School of Public Health said that discussing herd immunity “… presents people with an unrealistic vision of how the pandemic comes to a close and doesn’t account for the evolution of either the virus or the nature of disease in reinfections.” Source 

• The New York Times reports that the Delta variant has overwhelmed Iran. The official daily death toll is 500 to 600, although front-line doctors say it is closer to 1,000 people each day; lack of access to testing and care also make it likely that daily cases are far higher than the 40,000 that have been reported. The situation we are facing is beyond disastrous,” said Dr. Mahdiar Saeedian, a 39-year-old physician in Mashhad, Iran’s second-largest city. “The health care system is on the verge of collapse.”  Essential medical supplies, including intravenous fluids, oxygen tanks and antiviral medications are in short supply at hospitals and pharmacies; they are available in the black market at exorbitant prices. Doctors have posted videos on social media begging officials to act immediately to lock down the country and buy more foreign-made vaccines, while nurses are shown crying on state television.

The government – which has not imposed restrictions on super-spreading events – has also refused to purchase or accept donations of vaccines made in the UK and US, while Dr. Alireza Zali,  head of Tehran’s coronavirus committee, said officials had not allowed the purchase of foreign vaccines because of the expense. Source 

• Moderna issues a press release to announce that the US FDA has updated the emergency use authorization for its coronavirus vaccine to include a third dose for immunocompromised individuals ( solid organ transplant recipients and people with other conditions with equivalent level of immunocompromise) ages 18 and over. Source