Patients with cancer, especially those undergoing chemotherapy, have a higher risk of infections due to weakening of the immune system.
Vaccines work by stimulating the immune system to produce a response (antibodies) against a specific pathogen (i.e. viruses or bacteria). Vaccines have a very specific, targeted action.
The influenza vaccine (flu vaccine) is given yearly to train the immune system to fight against the most common strains of flu viruses circulating in the population (in that year). Flu vaccination is extremely safe and has proven benefits in reducing the risk of developing severe respiratory illnesses.
A less known fact is that the flu vaccine also helps reduce the risk of other life-threatening conditions, such as heart attacks. This occurs because heart attacks are linked to inflammation. During the colder seasons, common respiratory infections like influenza (even when symptoms are not that obvious) produce inflammation. Having a good, specific immune response against influenza (which is acquired through vaccination) reduces the amount of inflammation needed to fight off the infection. This in turn helps lower the risk of heart attacks.
Because the immune system is weakened in patients with cancer and because vaccines work together with the immune system, it is not clear whether they are as effective as in healthy persons.
This systematic review looked at data from 4 trials (2124 participants in total). Researchers compared mortality rates in cancer patients who were vaccinated for influenza versus those who were not.
Results showed a tendency towards lower overall mortality in cancer patients who had been vaccinated. The number of hospitalizations was reduced in one of the four studies, while another trial reported similar numbers.
Keeping in mind that the flu vaccine is very safe, the authors concluded that it can help reduce mortality in cancer patients (even those undergoing chemotherapy). However, larger trials are needed to confirm this.
Eliakim-Raz N, Vinograd I, Zalmanovici Trestioreanu A, Leibovici L, Paul M. Influenza vaccines in immunosuppressed adults with cancer. Cochrane Database of Systematic Reviews 2013, Issue 10. Art. No.: CD008983. DOI: 10.1002/14651858.CD008983.pub2