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Old 10th December 2020, 01:26 PM   #126
Skeptic Ginger
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Originally Posted by Puppycow View Post
Interesting. That's what I wanted to know. 52% effective. In that case, probably best to just go based on who is most vulnerable, and those who care for the vulnerable, and front line health care workers, and then so forth and so on.

If it had been 60% or 70% effective with a single dose, then it might make sense at least mathematically to get everyone a first dose before the second one. Except also, even in that case, get the old and otherwise most vulnerable people protected first.

I suspect Japan is going to approve it later than Britain or the US, because they've always been rather slow to approve vaccines compared to other countries. Also, the infection rate and the death toll is lower. I've heard it might not be available here until next spring. There is one Japanese company developing a vaccine, but they are so far behind (I think they are just starting phase 2 trials). By the time they are ready for phase 3, everyone's going already be getting the other vaccines. It's going to be hard to recruit volunteers for a trial when there's already a proven vaccine available and you know you won't be getting a placebo.
There's an additional problem relying on 50-60% effectiveness with one dose is we don't know how long that immunity lasts. It might only last a month without the second dose.

The effectiveness here is based on some pretty small numbers of COVID cases in a large sample size over a limited time frame. People got the vaccine or placebo. I believe there were about 30K of them. A dozen or so got infected, most of them in the placebo group and of the few who got infected in the vaccine group, none had serious disease. There were two additional factors to consider, one was the length of the study which I believe was only a few months and certainly was no longer than 6 given the time frame developing vaccine.

The second issue which is important to consider is that the people who volunteered to be in this study would have also been on average more cautious trying to prevent infection. I don't imagine many anti-maskers were in the volunteer group.

So when the vaccine manufacturer makes a claim that the vaccine was X% effective, that is based on a study with significant limitations.

If we use the study results as a basis for decision making I think it's a pretty safe bet that an interval for the second dose has some leeway.

So are we better off doubling the number of people we vaccinate early on (knowing there will be enough vaccine for those 2nd doses eventually) or are we better off vaccinating half as many people with both doses?

Another consideration is the vaccine wasn't tested on too many people over 70-80 years old. They tend to have a poorer response to vaccines in general.

If carrying out the vaccine program could divvy people up easily, I would think people over 70 (or 80) and people who are immunocompromised should get 2 doses on schedule, everyone else with intact immune systems should get one dose and a delayed 2nd dose.

Keep in mind all of these people should consider themselves to be potentially contagious if they are exposed to the virus. IOW quarantine rules would be the same.

What will be tricky is knowing when we should open back up. We need to knock the virus down then do meticulous contact tracing. People are going to jump the gun and that might mean it takes longer to knock the virus down.
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