I am currently working on applying a method for assessing vaccine durability proposed by Fintzi and Follman (2021) within Stata. The paper provides implementation using SAS and uses start, stop setup with removal of a 30 day period from each vaccinated individuals risk period.

Example data and SAS implementation
Obs id arm period start stop event vac timevac
1 1 0 1 35 65 0 0 95
2 1 0 2 95 370 0 1 95
3 2 1 1 45 80 0 1 45
4 2 1 2 110 400 0 1 45
PROC PHREG DATA=newest;MODEL (start, stop)*event( 0 )=vac vactime/ itprint rl ;vactime=vac*(stop-timevact);IF vac=0 THEN vactime=0;RUN;

I would greatly appreciate any advice on how to implement this in Stata - curently, using stsplit t and t0 directly flow from one interval to another and not sure how to implement this "gap"


Fintzi J, Follmann D. Assessing vaccine durability in randomized trials following placebo crossover. Stat Med. 2021 Nov 30;40(27):5983-6007. doi: 10.1002/sim.9001. Epub 2021 Apr 29. PMID: 33928660; PMCID: PMC8242890.