For cancer patients, is the third dose of vaccination a necessity or a luxury?

The current situation of the SARS-CoV-2 pandemic is on the one hand to expand the coverage of the vaccine, on the other hand, there are variants that damage the effectiveness of the vaccine and enhance the spread of the virus
.

The unfair distribution of vaccines has caused some developed countries to plan or provide a booster third dose of vaccine to their entire qualified population, but some African countries are still waiting for the first dose of vaccine

There is no doubt that patients with hematological malignancies do need a third dose of vaccination in order to increase the chance of seroconversion
.

However, most studies on solid tumor cancer patients have proven that most patients achieve seroconversion after the standard two vaccinations

In addition, in many studies, a small number of patients who did not undergo seroconversion usually suffer from underlying hematological diseases, as shown in the Danish series and the French lung cancer series
.

To be sure, some of these studies have also proved that the frequency of seroconversion observed after the first administration is lower, and the overall antibody level of patients with solid tumor cancer is lower than that of the general population

A similar French study also proved that 95.
2% of solid tumor cancer patients had seroconversion, but a trend of low antibody levels and delayed seroconversion was also observed (less than half of the conversions were 3-4 weeks after the first dose)
.

These results were further reproduced in another larger French study, where metastatic disease and ongoing chemotherapy are common features of 6% of non-seroconverters

immunity

CAPTURE is a British cancer patient vaccination response study.
Most patients were vaccinated with AZD1222 (ChAdOx1) viral vector vaccine, extending to the period of Delta mutation superiority
.

After the second dose, patients with solid tumors retained the neutralizing activity of the anti-Delta variant (albeit at a reduced level), roughly similar to the healthy cohort, and contrary to the significant suppression of immune responses observed in patients with hematological malignancies

Infect

Currently, cancer patients have limited experience in using the third dose
.

In a phase I trial in Arizona, 31 solid tumor cancer patients received a third dose of BNT162b2 mRNA vaccine one week after the median neutralizing antibody titre increased significantly (although the level was lower than healthy controls after the second dose)

So, can we provide this third dose of vaccine for solid tumor cancer patients to people in developing countries? This may be their first dose of vaccine
.

Not exactly
.

First, it must be considered that the proportion of non-seroconverting cancer patients is small but significant: in some of the above studies, the proportion of patients reaching 16% is basically as vulnerable as unvaccinated individuals, and are high- risk patients for COVID-19 and death

COVID-19

Therefore, these patients should be considered a priority for vaccination, even if this is their third dose
.

Can we distinguish which patients did not respond to the first two doses and only provide them with the third dose? Most studies are inconclusive on the risk factors of non-seroconversion in solid tumor cancer patients.

In the long run, it is in our best interest to end this epidemic as soon as possible
.
However, unless we solve this problem on a global scale, the pandemic will not end: the oncology community should be at the forefront of vaccine equity, seeking rapid vaccination for cancer patients in developing countries, while promoting coordination against new viruses The emergence of variants and the resurgence of the fight against further viruses
.

Original link: https://pubmed.
ncbi.
nlm.
nih.
gov/34773904/

https://pubmed.
ncbi.
nlm.
nih.
gov/34773904/

Vaccine third dose and cancer patients: necessity or luxury?

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