Vaccination Against Covid-19 in Patients with Cancer – What We Know and What We Don’t?
Dr. Harish P, Consultant – Medical Oncology
Ever since the coronavirus pandemic brought the world to a standstill back in March, there’s been talk of a vaccine. Cancer patients are especially worried because of additional comorbidity because of their underlying disease and comorbidity secondary chemotherapy.
In lung and breast cancer patients, the immune response to vaccination appears adequate. In a study of patients with various solid tumours, the response to vaccination was better than in patients with lymphoma. Special cases may include hematologic malignancies in which the immune system has been destroyed, and profound immunosuppression occurs. Data on immunization during this immunosuppressed period is scarce, but the data available suggests that once cancer patients are through this immunosuppressed period, they can be vaccinated successfully.
In patients receiving chemotherapy, efficacy rates are expected to be lower than in the general population, but not in patients receiving immunotherapy. Whenever possible, the administration of the vaccine should be performed before initiation of chemotherapy. In patients who have already initiated chemotherapy, the existing data do not support a specific timing of administration with respect to chemotherapy infusions.
Accumulated evidence from influenza vaccinations suggests that patients with cancer are able to mount a protective immune response from anti-SARS-CoV-2 vaccines, though the level of immunity may be modulated by a range of factors (the type of cancer, type of therapies and timing of administration, pre-existing immune dysfunction, fitness etc.)
To date, the UK has secured early access to 357 million doses of 7 of the most promising vaccine candidates, including:
- BioNTech/Pfizer – Phase 3 – 40 million doses secured
- Oxford/AstraZeneca – Phase 3 – 100 million doses secured
- Moderna – Phase 3 – 7 million doses secured
- Novavax – Phase 3 – 60 million doses secured
- Janssen – Phase 3 – 30 million doses secured
- GSK/Sanofi – Phase 1 / 2 – 60 million doses secured
- Valneva – Phase 1 / 2 – 60 million doses secured, with an option to acquire a further 130 million if the vaccine is proven to be safe, effective and suitable.
The latter vaccines, particularly attenuated live virus vaccines, may not be a good choice for cancer patients. Especially in those with rapidly progressing disease or on chemotherapy, attenuated live viruses may cause a low-grade infection.
Incidentally, the technology used in the genetic or mRNA vaccines developed by Pfizer-BioNTech and Moderna was initially developed for fighting cancer, and studies have shown that patients can generate immune responses to cancer-associated proteins with this type of vaccine. These genetic vaccines could turn out to be the most effective for cancer patients, especially those with solid tumours.
Our understanding is very limited right now. Neither the Pfizer-BioNTech nor the Moderna early data discuss cancer patients.
Two of the most important questions for cancer patients are dosing and booster scheduling. Potential defects in lymphocyte function among cancer patients may require unique initial dosing and booster schedules. In terms of timing, it is unclear how active therapy might affect a patient’s immune response to vaccination and whether vaccines should be timed with therapy cycles.
Vaccine access may depend on whether cancer patients are viewed as a vulnerable population. Those at higher risk for severe COVID-19 clearly have a greater need for vaccination. While there are data suggesting that cancer patients are at higher risk, they are a bit murky, in part because cancer patients are a heterogeneous group. For example, there are data suggesting that lung and blood cancer patients fare worse. There is also a suggestion that, like in the general population, COVID risk in cancer patients remains driven by comorbidities.
Read our blog to know more about DOS AND DON’TS of Cancer Patients during Covid 19.