A new study shows the persistent syndrome of Covid-19 after-effects known as long Covid can develop after “breakthrough” infections in vaccinated people. Other new findings suggest a gene that helps the coronavirus reproduce itself might contribute to life-threatening Covid-19 in young, otherwise healthy people.

Pfizer, Moderna, and AstraZeneca have been running “dress rehearsals” by adapting their current formulations of Covid-19 vaccines to match present known SARS-CoV-2 variants.

People who got Johnson & Johnson’s Covid-19 vaccine as a first shot had a stronger immune response when boosted with vaccines from Pfizer/BioNTech or Moderna, a study run by the National Institutes of Health showed on Oct. 13.

AstraZeneca’s antibody cocktail against Covid-19, which has proven to work as a preventative shot in the non-infected, was also shown to save lives and prevent severe disease when given as treatment within a week of first symptoms.

The Delta variant of the coronavirus does not appear to cause more severe disease in children than earlier forms of the virus, a UK study suggests. Another study found that in Covid-19 survivors, important components of the body’s immune response called memory B cells continue to evolve and get stronger for at least several months, producing highly potent antibodies that can neutralize new variants of the virus.

A new study helps quantify the improved protection against Covid-19 achieved with a third booster dose of the vaccine from Pfizer Inc. and BioNTech SE in cancer patients who are undergoing chemotherapy.

AstraZeneca requested emergency use authorization from U.S. regulators for the company’s new treatment to prevent Covid-19 for people who respond poorly to vaccines because of a weakened immune system.

CanSino Biologics Inc.’s single-dose Covid-19 vaccine – given at a lower dosage than that for adults – is safe and triggers an immune response in children aged 6-17, results from a small trial showed.

U.S. Food and Drug Administration scientists said on Sept. 15 that booster doses of Pfizer’s Covid-19 vaccine may not be needed, even though the third shot generates a higher immune response in recipients.

Johnson & Johnson said the company’s Ebola vaccine regimen demonstrated antibody immune responses in adults and children, citing data published in the Lancet Infectious Diseases journal.