Translation of a-t 2021; 52: 55
 

CURRENT ADR NETWORK REPORT

INR changes after a COVID-19 vaccination

A 67-year-old woman taking phenprocoumon (MARCUMAR, generics) for anticoagulation because of a mechanical mitral valve replacement was vaccinated with the COVID-19 vector vaccine from AstraZeneca (AZD1222; VAXZEVRIA). Before the vaccination her INR level was in the therapeutic range at 3.1 but three days after the vaccination it was significantly below this range at 0.8. As a result she took an additional tablet of phenprocoumon and injected the low-molecular-weight heparin enoxaparin (CLEXANE, generics). Following consultation with the doctor providing her treatment as the INR remained too low at 1.8, the following day she also increased her usual dose of phenprocoumon (this time by half a tablet) and injected heparin again. The INR was back to the desired range five days after the vaccination at 3.3. The patient indicated that she had not consumed any foods containing vitamin K and had not forgotten to take any medication (NETZWERK report 18.045). We have also documented changes in the INR in combination with other COVID-19 vaccines. All of those affected were receiving anticoagulation because of a mechanical aortic valve replacement. A 56-year-old man who manages his own INR and always keeps it between 2.6 and 3.0 measured fluctuating INR values of between 1.9 and 4.4 following the vector vaccine by Janssen (Ad26.COV2.S; COVID-19 VACCINE JANSSEN) (18.103). An INR of over 7 was determined on admission to hospital in an 80-year-old woman with a heart attack and a 79-year-old man with sepsis caused by salmonella five days and two weeks respectively after vaccination with the mRNA vaccine by BioNTech/Pfizer (BNT162b2; COMIRNATY) (18.081 and 18.082). The extent to which the acute diseases could have affected the INR value remains unclear. The database of adverse reactions held by the European Medicines Agency, EMA,¹ also documents reports of INR changes after vaccination against COVID-19: by mid-July 2021 there were 94 reports of an INR increase, 34 of an INR decrease, 7 of an abnormal INR and 6 of INR fluctuations for the vaccine by BioNTech/Pfizer, 17 reports of an INR increase and 4 of an INR decrease and 1 report each of an abnormal INR and INR fluctuations for the mRNA vaccine by Moderna (mRNA-1273; SPIKEVAX). There were 117 reports of an INR increase, 60 of an INR decrease, 14 of an abnormal INR and 6 of INR fluctuations for the vaccine by AstraZeneca, and 16 reports of an INR increase and 2 reports of an INR decrease and 1 report each of abnormal INR in connection with the vaccine by Janssen.¹ As far as we can see, drug authorities are not currently rating INR changes in connection with COVID-19 vaccines as a risk signal. As a precaution, however, the INR values should be carefully monitored in users of coumarin anticoagulants following a COVID-19 vaccination.

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