This Thread explains the controversy around delayed 2nd doses of #Covid19vaccines or lowering the amount in each dose. The debate really boils down to what science tells us about maximum protection for INDIVIDUALS versus maximum protection for POPULATIONS. US is individualistic

Individual perspective: The clinical trials were designed to give a specified vaccine dose to "prime" the immune system, followed by a second dose 2-3 weeks later. Using this 2-dose, set interval, strategy conferred near 95% efficacy for @pfizer & @moderna_tx vaccines.

The clinical trials cannot give any assurance of high efficacy & durability of immunity with any deviation from this 2-dose, set-interval, strategy. Thus, the science requires using clinical trial data for dosing as the only sure way to confer maximum immunity for indiv patients

Population perspective: In a health crisis, w/ deaths & hospitalizations spiraling, & vaccine scarcity, it's plausible delaying 2nd shots or halving doses could confer immunity on a larger pop, reducing chains of transmission. The UK is allowing 3-month intervals between doses.

Even though any given indiv will likely have less protection, a single dose dose confer some immunity. If more people can get even partial protection, it could save more lives overall. That is the thinking in the UK & elsewhere.

Where do I stand? While I usually see problems from a pop perspective, here I would stick w/ the science. It is taking a risk to deviate from the clinical trials. Also, by doing so, it would reduce public trust in the vaccine, which is vital.

There is no reason in a nation w/ such high capacities as the US that we can't produce more doses rapidly & invest in infrastructure to actually get the vaccine in people's arms. That is @JoeBiden's plan.

Should a delayed or diluted dose strategy be deployed in LMICs? It would seem inequitable if rich countries were better protected than poorer ones. I would look to @WHO to advise on dosing strategy as part of its pre-qualification process.

Overall, here's the goal:
* Produce ample vaccine supplies for the world
* Invest in vaccine infrastructure- robust health systems
* Make vaccines accessible & affordable for all
* Stick w/ the science
* Conduct clinical trials w/ different dosing strategies
* Learn & Protect