After reading the article:
First comparison:
Those who either got covid or got vaxed in Jan-Feb 2021. Results show that 4-7 months later (June-Aug) there are significantly fewer covid reinfections than vaxed breakthrough infections.
This shouldn't surprise us, because we had already heard that natural immunity lasts about 7-8 months.
Second comparison:
Those who got covid from March 2020 - Feb 2021 and those who got vaxed from Nov? 2020-Feb 2021.
Again, there were fewer covid reinfections than vaxed breakthrough infections, though by looking at this longer time span, we can see that the covid immunity seems to be waning, as indicated in the earlier post on the abstract.
BUT: Although they say that the covid recoverees came from March 2020-Feb 2021, their Figure 1 shows that the largest chunk of those were in the July-Nov 2020 period. So if immunity wanes, we're looking at mostly waning immunity for those who were infected in the summer, and presumably those infected in March have waned even more.
Third comparison:
They compared 14,000 who recovered from covid with 14,000 who recovered plus had the (recommended) one vaccine dose.
In those who recovered, there were 37 infections, 23 symptomatic infections, 1 hositalization.
Recovered plus one dose vax - 20 infections, 16 symptomatic infections, 0 hospitalizations
So it looks like the vaccine was somewhat helpful, but they say "we could not demonstrate significance in our cohort", that is, they still don't have enough data to say this definitively.
One problem I see with this part of the analysis is that in describing their groups, for "recovered from covid and had one dose" they included anyone who had been vaccinated at least SEVEN DAYS earlier. So it's possible that it takes longer than that for the vaccine to significantly affect the immune system, and that the one dose could be considered an effective booster after more time passes.
I can't figure out this conflict. Anyone else?
Results:
Examining previously infected individuals to those who were
both previously infected and received a single dose of the vaccine, we found that the
latter group had a significant 0.53-fold (95% CI, 0.3 to 0.92) (Table 4a) decreased risk
for reinfection, as 20 had a positive RT-PCR test, compared to 37 in the previously
infected and unvaccinated group.
Discussion:
Individuals who were previously infected with SARS-CoV-2 seem to gain additional
protection from a subsequent single-dose vaccine regimen. Though this finding
corresponds to previous reports24,25, we could not demonstrate significance in our
cohort.