Delaying the second dose of the Pfizer / BioNTech vaccine puts cancer patients exposed to the virus at risk of covid-19, and therefore the British government’s strategy to extend the interval between the two injections, taking it from 3 weeks to 12 to cope with the limited supply of vaccines, should be urgently reviewed for cancer sufferers. This is the conclusion of a study, not yet reviewed, conducted by researchers at King’s College London and the Francis Crick Institute, which analyzed the immune response of 205 people, 151 with cancer and 54 healthy, to the Pfizer vaccine.
Let’s say it right away, this is an English story that does not concern us directly, since the vaccination strategy in Italy follows the indications of the manufacturers on the interval between the first and second dose (which in the case of the Pfizer / BioNTech vaccine is 3 weeks) . However, the British study gives the opportunity to clarify the relationship between anti-covid vaccination, cancer and cancer therapies, and to reflect on the consequences of any delays.
Covid, oncologists ready to vaccinate
Delaying the second dose could leave cancer patients exposed for too long
The research found that three weeks after the first vaccine injection, antibody responses were found in 39 percent of people with solid tumors and 13 percent of those with blood cancers, compared with 97 percent of people without cancer. The survey also reports that when the second dose was given at the indicated time 3 weeks after the first, the immune response improved significantly for patients with solid tumors, as 95% of them had developed detectable antibodies against the virus (within two weeks of the second injection). In contrast, those who did not receive the second dose of the vaccine after 3 weeks saw no improvement: only 43% of patients with solid tumors and 8% of those with blood cancers developed detectable antibodies at five weeks. (from the first injection), compared with 100% of the 54 people in the control group (without tumors). Essentially, cancer patients would remain unimmunized for too long before the booster.
Review the UK vaccination strategy
As reported by the British newspaper Guardian, according to the authors of the study, these results indicate that a 12-week interval between doses is not good for those with cancer, and that the strategy of delaying the second injection risks exposing cancer patients to severe cases of Covid-19. “Our data provide the first real evidence of post-dose immune efficacy of Pfizer vaccine in immunocompromised patient populations,” said Sheeba Irshad of King’s College.
“We show – added Irshad – that after the first dose the majority of patients with solid and blood tumors remained unprotected until at least five weeks after the first injection, and that this poor efficacy after one dose can be recovered. with an early recall, on the 21st day. Based on our findings, we would like to recommend an urgent review of the vaccination strategy for extremely vulnerable groups. In the meantime, it is important that cancer patients continue to observe all public health measures in place when they go to hospitals, even after vaccination ”.
“The vaccine is very effective on healthy people and our study clearly shows that it can also bring immense benefits to cancer patients – explained Adrian Hayday of King’s College London and the Francis Crick Institute – but in most cases this only happens. after an early recall “.
In Italy
“In Italy we administer the vaccines according to the approved schedule, in the case of the Pfizer preparation with an interval of 3 weeks between the two administrations. And at a slightly different rate from region to region, once the oldest and the categories with priority, such as teachers for example, have been vaccinated, cancer patients undergoing treatment will also be vaccinated “, says Massimo Di Maio, national secretary of the ‘Italian Association of Medical Oncology (Aiom): “As a scientific society we asked, and obtained, that these patients be considered ultra-frail, as well as nephropaths, cardiologists or dialysis patients and others”.
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Immunosuppressive treatments
“Chemotherapy, as we know, lowers the immune defenses and makes the body’s response to external stimuli less ready – explains the oncologist – but also immunotherapy drugs, interfering with the delicate mechanisms of the immune system, could compromise the normal response to infections. Therefore, those who undergo immunotherapy are also considered at risk. Hormonal treatments, for example those for breast cancer, do not have a significant impact, since they are not immunosuppressive and do not interfere with the mechanisms of the immune system ”.
Having said all this, the numbers of the English study provide interesting information: “They say that after a single dose the immune response capacity may be less strong in cancer patients than in others. While we never thought vaccines were unsafe for our patients, and there was no reason to actually think so, we feared they were less effective. And the study indicates that after a single dose our patients actually respond less well to the vaccine – continues Di Maio – so it is good to consider them fragile, and precisely because they are immunosuppressed people, to guarantee them the greatest possible protection, all the more reason they go vaccinated. Let’s get the vaccines early and everyone ”.
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