Vaccines
This article says that NACI recommended boosters for a few more groups:
- People who got two doses of AZ or one of J&J, on the grounds that those seem to wane over time.
- People over 70 who could become severely ill from the disease.
- People from First Nations, Inuit and Metis communities.
- Front-line health-care workers with a short interval between their first two doses. (Note that many health-care workers were vaccinated early on, when the short dose interval was in effect.)
This report from the US CDC says that vaccine-acquired immunity is 5.5x better than infection-acquired immunity.
Variants
This preprint found that the difference in susceptibility to Delta vs. previous strains was age-dependent. Kids 10-19 were 1.92 times more susceptible to Delta than to previous strains, while people over 50 didn’t see a whole lot of difference between Delta and other strains.
This Twitter thread walks through the latest report from Public Health England on variants, focusing on AY.4.2 (“Delta-plus”). Spoiler: nothing scary. About the only difference they found is that Delta+ has a vaccine effectiveness of 81% instead of 83%.
Transmission
This article says that a third of the white-tailed deer in the northeastern US have antibodies to SARS-CoV-2. 🙁 The deer didn’t appear sick, but having animal reservoirs means that COVID-19 will never go away.