Do you mean you want to paste together the elements of each vector? For example:
paste(c("hiv3=0", "comdiab=0", "ppl=0"), collapse=", ")
[1] "hiv3=0, comdiab=0, ppl=0"
I'm not sure what type of object your string vectors are stored in, but here's an example where they are in a list:
library(tidyverse)
x = list(c("hiv3=0", "comdiab=0", "ppl=0"),
c("fxet3=1", "hiv3=0", "ppl=0"),
c("fxet3=1", "escol4=0", "alcool=0", "tipores3=1"),
c("escol4=0", "alcool=0", "ppl=0", "tipores3=1"))
map(x, paste, collapse=", ")
[[1]]
[1] "hiv3=0, comdiab=0, ppl=0"
[[2]]
[1] "fxet3=1, hiv3=0, ppl=0"
[[3]]
[1] "fxet3=1, escol4=0, alcool=0, tipores3=1"
[[4]]
[1] "escol4=0, alcool=0, ppl=0, tipores3=1"