However, a second dose of the vaccine after three weeks significantly increased its protection, and the researchers had earlier boosted this group in the UK. The UK’s vaccine strategy currently involves a twelve-week gap between doses of coronavirus vaccines; Pfizer recommends 21 days between doses.
The study analyzed the impact of the Pfizer-BioNTech vaccine on 205 participants – 54 healthy volunteers and 151 elderly patients with solid cancers, such as breast or prostate cancer, and hematological (blood) cancers, such as leukemia. The pre-print study has not yet been reviewed or published by peers.
The researchers searched for levels of antibodies and T cells in their blood to identify the level of immune response against the coronavirus.
Three weeks after one dose of the vaccine, an antibody response was found in 39% of cancer patients and only 13% of people with blood cancer. The response rate among healthy volunteers was 97%.
In solid cancer patients who received a second dose three weeks after the first dose, the antibody response shot up to 95% within two weeks after the boost. Not enough booster vaccines were given to patients with blood cancer to determine the response in the group.
Further evidence of the need for a boost was shown by the fact that antibody levels rose to 43% only five weeks after their first dose in people with solid cancer and 8% in those with blood cancer. It was 100% in healthy volunteers.
“Our data provide the first true evidence of immune efficacy after one dose of Pfizer vaccine in immunocompromised patient populations. We show that most solid and hematologic cancer patients remained immunologically unprotected after the first dose until at least five weeks after the primary injection. poor efficacy of one dose can be saved on day 21 with early reinforcement, “said dr. Sheeba Irshad, a senior clinical lecturer at the School of Cancer and Pharmaceutical Sciences, who led the research.
“Based on our findings, we would recommend an urgent review of the vaccine strategy for clinically extremely vulnerable groups. Until then, it is important that cancer patients continue to keep all social health measures in place, such as social distance and protection when visiting hospitals, even after vaccination, ”Irshad added in a statement.
Stephen Evans, professor of pharmacoepidemiology at the London School of Hygiene & Tropical Medicine, stressed that certain limitations need to be considered.
“The change in UK policy around delaying a second dose of vaccine has allowed the authors to make comparisons between those who received a second dose within 21 days and those who did not. “does not provide information on those who received a second dose” after a twelve-week delay, “he said in a statement to the UK’s Science Media Center.
“Nevertheless, these results suggest that the vaccines may not protect patients with cancer as well as those without cancer,” he added.
“All of these findings are consistent with our understanding of the immune system function in cancer patients,” said Shoba Amarnath, a research fellow at the University of Newcastle at the Newcastle University Center for Cancer. “We know that the immune system within cancer patients is compromised compared to healthy controls. Therefore, a second vaccine boost prepares the unregulated immune system to function at the same efficiency as healthy controls.
“The data in the study support the notion that a significant second-dose delay in solid cancer patients will prolong the period when cancer patients are at risk of SARS-CoV-2 infection.”