In a case-control study published as a comment in The Lancet Oncology, researchers note that considering the high mortality of cancer patients who contract the SARS-CoV-2 virus, the benefits of vaccination seem to outweigh the potential harm
Israel has been one of the leading countries in vaccination against COVID-19. With a population of nine million, the country has vaccinated approximately five million people. The main immunizer used is NT162b2, an mRNA vaccine that conferred 95% protection against COVID-19 in individuals aged ≥ 16 years. Safety over a median of two months was similar to that of other viral vaccines .
As reported by the investigators, the institutional policy of the Oncology Division of Tel Aviv Sourasky Medical Center (TLVMC) and the Oncology Unit of Bnei-Zion Medical Center, Haifa, allowed and encouraged vaccination for all cancer patients under active treatment. Only patients with previous COVID-19 infection, as well as those with active infection or ongoing immune-related adverse events, were excluded from the vaccination campaign.
The analysis included 134 patients under treatment with immune checkpoint inhibitors who received both doses of the vaccine at the two institutions, as well as 134 healthy age- and sex-matched controls who were also vaccinated.
The most common adverse effects in the population under immunotherapy after the first dose of BNT162b2 were local events, with 21% having pain at the injection site. Systemic effects included fatigue (4%), headache (2%), muscle pain (2%) and chills (1%).
After the second dose of vaccine in patients receiving immunotherapy, four (3%) were admitted to the hospital: three due to complications related to cancer and one due to fever. All were discharged after treatment.
The most common local adverse effects of vaccination were local pain (63%), local swelling (9%) and local rash (2%). Systemic effects, meanwhile, were muscle pain (34%), fatigue (34%), headache (16%), fever (10%), chills (10%), gastrointestinal complications (10%) and flu-like symptoms (2%). No adverse reaction required hospitalization or any other special intervention.
Overall, systemic adverse reactions occurred in 32% of 116 patients treated with immune checkpoint inhibitors alone and in 44% of 18 who received immunotherapy plus chemotherapy (χ2 P test = 0.29). No new immune system-related adverse reactions were observed.
No significant difference in the incidence of systemic adverse events after the second dose was observed between patients versus controls for fatigue (P = 0.76), headache (P = 0.52), fever (P = 0.21), gastrointestinal effects (P = 0.29), chills (P = 0.70) or flu-like symptoms (P = 0.32). Muscle pain was significantly more common among patients (P = 0.024), but no immune-related myositis was observed.
The investigators concluded that the data support the short-term safety of the BNT162b2 mRNA COVID-19 vaccine in cancer patients on treatment with immune checkpoint inhibitors. However, rare side events may be identified when larger cohorts are investigated. Considering the high mortality of cancer patients who get COVID-19, the benefits of vaccination seem to outweigh the potential harm.