With the rollout of COVID-19 vaccination programmes around the world, how and when to vaccinate individuals with haematological conditions becomes an increasingly pressing matter. Patients with haematological malignancies are at a high risk of infection because of immune deficiencies, which result from the underlying disease and specific therapies. Vaccination is possible for these patients, and their increased risk of adverse outcomes from COVID-19 compared with the general population, or even other patients with cancer, means they should be prioritised. Stem-cell transplantation makes the timing of vaccination even more important. Many patients will lose their immunity following transplantation, but can generally begin to be vaccinated around 3 months after the procedure. However, the new COVID-19 vaccines have not been tested in patients with haematological malignancies or those who have undergone transplantation, so it is not yet clear what level of protection and type of immune response will result from vaccination. Herd immunity from the general population might be what is required to ensure safety for these patients.
For patients with other haematological conditions, such as sickle cell disease, thalassaemia, and rare inherited anaemias, the general consensus is that being vaccinated against COVID-19 will be beneficial, and that these people should be vaccinated as soon as the vaccine is available to them. For individuals with bleeding disorders who are receiving treatment to reduce bleeding, intramuscular vaccination can be scheduled shortly after such treatment. For those being treated with anticoagulation, there should be no contraindication for receiving an intramuscular vaccine, although patients receiving warfarin with a supratherapeutic international normalised ratio (INR) should wait until their INR is below 4.
Although it is hoped that COVID-19 vaccines will change the tide of the pandemic, much work is still to be done to understand the disease. It will take time before there is sufficient global distribution of the various vaccines to control the pandemic, and careful monitoring of those with haematological conditions is imperative.
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