Use in patients being treated with warfarin

According to the UK Health Security Agency (UKHSA – formerly known as PHE) Immunisation Against Infectious Disease (the Green Book) the vaccine can be given intramuscularly to individuals on warfarin who are up-to-date with their scheduled INR testing and whose latest INR is below the upper level of the therapeutic range.

A fine needle (equal to 23 gauge or finer calibre such as 25 gauge) should be used for the vaccination, followed by firm pressure applied to the injection site without rubbing for at least two minutes. The individual should be informed of the risk of haematoma from the injection.

If there is any doubt about the level of anticoagulation control, the clinician responsible for prescribing and monitoring the patient’s anticoagulant treatment should be consulted.

Use in patients being treated with a Direct Oral Anticoagulant or DOAC (i.e. apixaban, dabigatran, edoxaban or rivaroxaban)

According to the Green Book the vaccine can be given intramuscularly to individuals who are stabilised on a DOAC.

Advice on reducing the risks of vaccination leading to a haematoma are as described for warfarin above.

Use in patients with bleeding disorders

According to the Green Book the vaccine can be given intramuscularly to individuals with a bleeding disorder. If the patient is receiving regular treatment to reduce bleeding (e.g. patients with haemophilia) vaccine administration can be scheduled to occur shortly after this treatment is given.

Use in patients with a history of clots or bleeding disorders

In light of the association between administration of the AstraZeneca vaccine and the development of serious thromoboembolic events accompanied by thrombocytopenia in a relatively small number of patients the Green Book offers the following advice:

• there is no reason to believe that individuals with a past history of clots or of certain thrombophilic conditions would be at increased risk of this very rare condition.
• there is no evidence that pregnant women, those in the post-partum or women on the contraceptive pill are at higher risk.
• contra-indications to vaccination with the AstraZeneca COVID-19 vaccine have now been amended to include individuals who have a history of a previous episode of heparin-induced thrombocytopenia and thrombosis (HITT or HIT type 2). These individuals may be offered vaccination with an alternative COVID-19 vaccine.
• individuals who do develop this condition after their first vaccination should be considered for a second dose of an alternative mRNA vaccine after at least 12 weeks has elapsed from the implicated dose.

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