So, good news, bad news, and just news, according to Megan Ranney. The bad news is the Delta variant is significantly more contagious. The good news is that the Pfizer and AZ vaccines work against it, and Moderna probably does. The "just news" is that vaccination rates by state seem to matter, so your behavior might be different in different places.
Also, her quick summary about the myths around vaccines.
That's interesting. I had just read that half the adults infected in Israel with Delta were fully vaccinated.
ReplyDeletehttps://nypost.com/2021/06/27/delta-variant-outbreak-in-israel-infecting-vaccinated-adults/
Grim: I had just read that half the adults infected in Israel with Delta were fully vaccinated.
ReplyDeleteThat's about the expected value. Consider a toy example with a population of 100 who are exposed, 80 of whom are vaccinated. The 20 who are not vaccinated become infected. With a vaccine efficacy of 80%, about 20% of the 80 who are vaccinated become infected, or 16. Notably, the cases involving those who are vaccinated are generally milder.
That example assumes both a 100% contagion rate among the unvaccinated and a lack of herd immunity even at 80% vaccination. Israel has a 65% fully vaccinated population and it’s still happening.
ReplyDeleteAs noted, it was a toy example. It shows that if the disease is still prevalent, and immunization high, then vaccinated people are expected to constitute a larger portion of infections than you might otherwise suppose.
ReplyDeleteConsider if 100% of the adult population were vaccinated. Children would still be carriers, and 100% of adult infections would occur in vaccinated adults.
Grim: That example assumes both a 100% contagion rate among the unvaccinated and a lack of herd immunity even at 80% vaccination. Israel has a 65% fully vaccinated population and it’s still happening.
Herd immunity depends on infectivity of the variant, efficacy of immunization, and the level of vaccination. About a third of the population of Israel is still unvaccinated, often in large clusters. This means that the disease will continue to circulate, and many vaccinated individuals will still become infected and also transmit the disease. Herd immunity is not so easy.
The evolution of variants shows how poor health care in the developing world and political resistance to effective social policies to limit the spread of disease (such as in the U.S.) can affect the health of everyone.