Summary
How cancer patients are responding to the COVID vaccine. Results show poor response after first dose and empahsize need to avoid delay between doses.
Cancer Patients Respond Poorly to First COVID mRNA Vax Dose
Barely one-quarter of patients with cancer obtained protection against COVID-19 after one dose of the Pfizer/BioNTech vaccine, a prospective study showed.
The data found a “strikingly low” 28% immune efficacy rate in patients with cancer, including 13% in patients with blood cancers. In contrast, first-dose seroconversion occurred in 97% of a healthy control group, Adrian Hayday, PhD, of King’s College London, and co-authors concluded in a report posted to the preprint server medRxiv.
A second dose at day 21, however, brought adequate immunity to nearly all the cancer patients, they said.
“These data support prioritization of cancer patients for an early (21-day) second dose of the BNT162b2 vaccine,” Hayday and colleagues wrote in the preprint. “Given the globally poor responses to vaccination in patients with hematological cancers, post-vaccination serological testing, creation of herd immunity around these patients using a strategy of ‘ring vaccination,’ and careful follow-up should be prioritized.”
“Delayed boosting potentially leaves most solid and hematological cancer patients wholly or partially unprotected, with implications for their own health, their environment, and the evolution of variant-of-concern strains,” the researchers added. “Prompt boosting of solid cancer patients quickly overcomes the poor efficacy of the primary inoculum in solid cancer patients.”
In general, patients with cancer have been excluded from clinical trials of COVID-19 vaccines, following evidence of sustained immune dysregulation, inefficient seroconversion, and prolonged viral shedding after COVID-19 infection. The exclusion has raised questions about the vaccines’ safety and efficacy in patients with cancer, Hayday and co-authors noted.
Moreover, British health officials changed the interval between the first and second dose to 12 weeks to maximize population coverage. Whether that interval is appropriate for patients with cancer, however, particularly those on systemic anti-cancer therapy, remains unclear, the authors continued.
To examine the issue, they prospectively studied 151 patients with cancer (solid tumors and hematologic malignancies) and 54 healthy individuals (mostly healthcare workers) who received an initial dose of the Pfizer/BioNTech vaccine against COVID-19. Blood samples were obtained from all study participants at baseline and at 3 and 5 weeks after vaccination.
In keeping with the British policies for COVID vaccination, participants vaccinated from Dec. 8 to 29 received two doses of vaccine, 30 days apart. Participants vaccinated after that received the initial dose and remained in follow-up to the planned booster dose 12 weeks later.
The primary endpoint was humoral and cellular immune response in the patients following the first vaccine injection. Immune efficacy was defined by antiviral IgG titers 21 days after the initial (priming) vaccine dose. The secondary endpoint was vaccine safety.
The patients with cancer had a median age of 73, and two thirds had one or more comorbid conditions. Solid malignancies accounted for 63% of the patient population and hematologic malignancies for 37%.
Most of the patients with solid tumors had late-stage disease associated with a cancer diagnosis exceeding 24 months. The healthy control group consisted of vaccine-eligible individuals who were not age-matched to the patients.
