They are looking at a relatively rare event over a set time period with multiple variables. It’s beyond what I’ve ever done, but they used something called a proportional hazards model. Specifically a Cox regression. They sort of describe what went into it in the graph caption. The 66% came from that model.
The numbers in the parentheses is the 95% confidence interval. It means you are 95% confident that the true efficacy lies between those numbers. The confidence interval in this case is based on the number of people in each group, the number of positive results and the overall population. If you have a relatively small amount of people in each group in respect to the overall population and have relatively few positive tests then your confidence interval can be pretty wide. They had more data accumulated before the delta variant. That’s why the confidence interval for vaccine efficacy is much more narrow (81-96) for pre-delta efficacy.
Same here I ended up getting vaccinated even after being infected. I waited a long time though for the simple reason of wanting to wait to see what new studies would come out since it’s still a dicey grey area depending which report you look at. I don’t see a reason not to be hesitant after getting covid like we did.
I was reading this while ago, it seems new information keeps changing. The WHO still doesn’t recommend a booster and then there is this study in Israel whether right or wrong it fuels skepticism if you have been infected. I have seen quiet a few studies like this.
“The natural immune protection that develops after a SARS-CoV-2 infection offers considerably more of a shield against the Delta variant of the pandemic coronavirus than two doses of the Pfizer-BioNTech vaccine, according to a large Israeli study that some scientists wish came with a “Don’t try this at home” label. The newly released data show people who once had a SARS-CoV-2 infection were much less likely than vaccinated people to get Delta, develop symptoms from it, or become hospitalized with serious COVID-19.”
If they truly want to prohibit the unvaxxed from participating in society, then have the balls to go all out. Forbid them from participating, then that includes both sides of the coin.
From everything I’ve read (I believe it also involves 2 shots) it seems to be the most effective with the fewest side effects. I do wonder what the holdup is on approval or distribution. As I said, I know several people, mostly younger people who have not had covid, who seem very distrustful of Pfizer and Moderna, but could not be called “anti vaxxers” - they would get the Novavax tomorrow if it were available.
Because a healthy immune system and those other healthy habits are less effective at keeping you out of the hospital and lowering your chances of contracting it.