SARS-CoV-2 vaccination effect over coagulation in 60s patients treated with acenocumarol

Background and objective

After the SARS-CoV-2 vaccination campaign, we observed alterations in post-vaccination international normalised ratio (INR) in patients treated with acenocoumarol. The aim of the study was to investigate whether there is an association between the observed blood coagulation alterations and SARS-CoV2 vaccination.

Materials and methods

A retrospective, longitudinal, observational study of patients over 60 years of age vaccinated against SARS-CoV-2 and treated with acenocoumarol was conducted. The main variable measured was the INR before and after vaccination, and secondary variables were date of vaccination, age, sex, type of vaccine, and dose of acenocoumarol. Paired means were compared using non-parametric Friedman and Wilcoxon tests with Benjamini–Hochberg correction, and a linear regression analysis between age and differences between pre- and post-vaccination INR measurements. The analysis was performed on the total sample and by subgroups. Statistical significance was set at p-value < .05.

Results

Overall, statistically significant differences (Friedman, p-value < .05) were found between INR measurements in the total sample, women, Comirnaty® vaccine, and Sintrom® 1 g dose, although the differences found are weak (W-Kendall < 0.01). No statistically significant differences were found between specific pairs in INR measurements (Wilcoxon, p-value > .05). The goodness-of-fit of all linear regressions was R2 < 0.1.

Conclusions

The alteration of coagulation due to vaccination against SARS-CoV-2 is not a population or generalised effect, but a possible side effect, and reinforces the safety of SARS-CoV-2 vaccination in this type of patients.