Variants
This article suggests that one reason why Quebec is seeing so few Delta cases compared to other provinces is because they’ve got more of something else: A.2.5, first seen in Central America. It’s not a VOC yet, but they are keeping their eye on it.
Vaccines
This study of Pfizer found that neutralizing antibodies were higher for a long dosing interval (6-14 weeks) compared to a short interval (3-4 weeks).
This study, done with data from March to July 2021 in Houston, and the proportion of COVID-19 cases in double-vaxxed people was about three times higher for Delta than for every other strain.
Transmission
This preprint says that asymptomatic people in South Africa (which will probably have a high level of Beta cases) are about as likely to infect others as symptomatic people — 16% to 12%, respectively. Teens spread it just as well as older people, but pre-teens were less likely to catch COVID-19, and less likely to spread it if they caught it.
This study shows that it is possible with some relatively simple measures — for kids to ride school buses without spreading COVID-19.
Recommended Reading
This article talks about twins and COVID-19.
This article talks about why breakthrough cases are normal/expected.
This article talks about what things drive vax hesitancy (in the US, but probably applies reasonably well in Canada also).
This article breaks down how American’s time usage changed from 2019 to 2020.