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The efficacy of CoronaVac against SARS-CoV-2 in cancer patients

In a recent study published in the Journal of Medical Virology, researchers analyzed the efficacy of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines in preventing SARS-CoV-2 infection among cancer patients.

Study: The efficacy of BNT162b2 (Pfizer–BioNTech) and CoronaVac vaccines in patients with cancer. Image Credit: cortex-film / Shutterstock


Coronavirus disease 2019 (COVID-19) vaccination is one of the most efficient approaches for preventing SARS-CoV-2 infections and has a critical role in reducing the catastrophic consequences of COVID-19, particularly in cancer patients who have a poorer prognosis than the general public.

Although clinical trials have shown that vaccinations against SARS-CoV-2 have a high effectiveness rate, the impact of these vaccines on cancer patients is yet unknown. Existing reports depicted low seroconversion rates following full-dose (minimum two-dose) COVID-19 vaccinations in cancer patients compared to healthy controls. Moreover, there is little information on SARS-CoV-2 infections in cancer patients following COVID-19 vaccination.

About the study

In the present retrospective, single-center, descriptive, and cross-sectional study, the researchers evaluated the potency of the COVID-19 CoronaVac and BNT162b2 (Pfizer–BioNTech) vaccines against SARS-CoV-2 infections in individuals with cancer. The investigators analyzed the information from cancer patients sent to a university hospital’s medical oncology clinic from March 2020 to December 2021. The study included 2578 cancer patients with a history of SARS-CoV-2 infection or who were COVID-19 vaccine recipients. Patients who got the SARS-CoV-2 vaccine following COVID-19 and whose vaccination status or precise date of vaccination were uncertain were excluded from the study.

The researchers utilized a data collection form with three sections: 1) descriptive data about patients, 2) COVID-19 details, and 3) data on the SARS-CoV-2 vaccination for procuring data. They gathered information from patient information systems, patient files, and the Ministry of Health’s database.

Data from 2578 cancer patients were collated and documented on data collection forms. Receipt of at least two doses of either BNT162b2 or CoronaVac four weeks apart was considered full-dose vaccination in this research. A positive reverse transcription-polymerase chain reaction (RT-PCR) test 28 days following the last dose of vaccine was deemed the SARS-CoV-2 diagnosis.

Results and discussions

According to the study results, of the 2,578 cancer patients, 20,00 did not have a prior COVID-19 status, and 578 patients displayed a history of RT-PCR-confirmed COVID-19. In addition, 2,094 patients were fully vaccinated against COVID-19, whereas 484 volunteers did not get the two-dose vaccination. There was a statistically relevant difference in SARS-CoV-2 incidence between participants who received full-dose BNT162b2 vaccination and those who did not.

All other full-dose vaccinated cancer patients, including two-dose CoronaVac, two-dose CoronaVac+one-dose BNT162b2 vaccine, and three-dose CoronaVac, had a lower COVID-19 incidence than patients who did not get full-dose vaccination. Although there was no variation in SARS-CoV-2 occurrence between the two-dose BNT162b2 vaccine and the three-dose CoronaVac vaccine, a statistically relevant disparity existed among all other cohorts in the in-group analyses of full-dose vaccinated participants. 

The analysis of 578 cancer patients with a history of SARS-CoV-2 infection illustrated a statistically relevant variation regarding COVID-19 incidence between those who received full-dose vaccination and those who did not. Nevertheless, inter-group analysis among full-dose vaccinated cohorts revealed no statistically significant variation. 

The researchers assessed whether there was a link between COVID-19 vaccine doses and vaccine types delivered during chemotherapy in patients who received full-dose vaccination due to the established unfavorable impacts of chemotherapy on the immune response. However, no patients got regular corticosteroid therapy during the research period. Further, anti-SARS-CoV-2 antibody concentrations were not assessed after the COVID-19 vaccination in this study. 

Overall, the authors summarized that full-dose SARS-CoV-2 vaccination protected cancer patients from COVID-19. 


The study findings demonstrated that COVID-19 vaccination was an essential factor in protecting the cancer patients from SARS-CoV-2 infection like the common public. However, SARS-CoV-2-linked public health precautions like maintaining social distance, wearing a mask outside the house, and vaccinating close contacts of cancer patients should not be overlooked. The current study indicated that booster shots of SARS-CoV-2 vaccinations reduced the risk of COVID-19 in cancer patients. Therefore, booster doses of vaccinations against microbes that might cause novel pandemics in the future should be contemplated for cancer patients, although the experience was limited to the SARS-CoV-2 pandemic.

Collectively, based on the study findings, the researchers urge that COVID-19 vaccination initiatives should target this susceptible patient category, namely cancer patients, and a full-dose vaccination, i.e., minimum of two vaccine doses, should be completed among them as soon as feasible.

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