New research on the COVID-19 vaccine’s effect on cancer patients ‘The booster shot provides better protection that we thought’

The COVID-19 booster shot has a significant positive impact on the immunity of cancer patients. That is one of the conclusions of a large research study led by Antwerp University Hospital and carried out in collaboration with Maria Middelares General Hospital. ‘It doesn't even matter whether your first vaccine was the AstraZeneca or Pfizer vaccine. The protection after the booster is surprisingly high in almost all cancer patients.’

Individuals with cancer have a higher chance of becoming seriously ill from COVID-19 since they have lowered immunity. For this reason, they were among the first to be vaccinated against COVID-19 during the coronavirus pandemic. ‘However, when compared to healthy people, we saw that their immune system did not respond as well to those first two vaccines. They produced fewer antibodies’, says Dr Timon Vandamme, who collaborated in the study.

The researchers were then curious about what the effect might be from a third dose, or booster shot, in cancer patients. Together with the University of Antwerp and the Institute of Tropical Medicine, the researchers conducted a large study involving 442 patients and personnel associated with Antwerp University Hospital and Maria Middelares General Hospital in Ghent. Sciensano and The Fight Against Cancer (Kom op Tegen Kanker) supported the study. The results have been published in the journal Clinical Cancer Research.

‘We see that the booster shot does indeed make a huge difference. The immune system in individuals with cancer is literally boosted, which means they are then better protected against COVID-19. This is a significant difference in comparison with the first two vaccinations’, explains Vandamme. ‘We recommend that individuals with cancer receive all subsequent booster shots.’

Dr Timon Vandamme

In principle, the findings are applicable to all types of cancer. Patients with leukaemia, who often have a more severely suppressed immune system, also participated in this study. ‘When using medication, they barely reacted to the first two COVID-19 vaccines, but with the third dose, we even saw increased immunity in these individuals’, says Vandamme.

The researchers also examined whether the brand of the first two vaccines influences the booster effect. This means that there are cancer patients who received the first two vaccines from AstraZeneca and a third vaccine from Pfizer. Others received three doses of Pfizer.

As Vandamme notes, ‘We see that the number of antibodies is just as high in nearly everyone who receives the booster shot. Therefore, there are no significant differences with regard to the booster shot between homologous and heterologous vaccination. That is important because patients who were initially vaccinated with AstraZeneca produced slightly fewer antibodies than those who had received the two Pfizer vaccines. The booster compensates for that difference. For a vulnerable population, this has a big impact.’

The researchers also determined that nearly every patient also produced T-cells after receiving the booster. ‘These white blood cells, in addition to the antibodies, provide an extra layer of protection. We’re very happy, therefore, to see that these cells are also able to contribute to protection against COVID-19 in cancer patients.’

Does this now mean that, after receiving the booster shot, cancer patients can no longer be infected with COVID-19? ‘We infer that the chance of infection and hospitalisation with the current variants of COVID-19 is limited’, says Vandamme. ‘In order to know precisely how the antibodies and T-cells behave with regard to the COVID-19 virus, further research is needed.’

In conclusion, the entire research team would like to thank all the patients for having participated in the study.