Difference in the long term safety of tenofovir disoproxil fumarate (TDF) versus tenofovir alafenamide (TAF0)

Is there a difference in the long term safety of tenofovir disoproxil fumarate (TDF) versus tenofovir alafenamide (TAF) used for HIV pre-exposure prophylaxis?
my part is to answer question 3 and 4 (which is below):

  1. How will you get your study participants? Recruit from 2019 to 2021, or until 100,000 initial participants 5 cities, 20,000 each San Francisco Houston Atlanta NYC Seattle
  2. For trials —How will you randomize? Why? Randomly assigned TAF vs TDF, ensure baseline population demographics are comparable Double blind, randomized, parallel assignment.

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