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COVID-19 vaccinated cancer patients at increased risk of breakthrough infections

Rod Tucker
13 April, 2022  

COVID-19 vaccinated cancer patients have a greater risk of breakthrough infections leading to higher rates of hospitalisation and mortality

COVID-19 vaccinated cancer patients have been found to be at a higher risk of breakthrough infections and which are associated with a substantial risk of hospitalisation and mortality. This was the conclusion of a retrospective cohort study of electronic health records by a team from the Center for Artificial Intelligence in Drug Discovery, Case Western Reserve University, Ohio, US.

Patients with cancer have been found to be at a significantly increased risk for COVID-19 infection and worse outcomes though fortunately, COVID-19 vaccination has been shown to be associated with lower infection rates in cancer patients. However, despite vaccination, the occurrence of breakthrough infections has also been reported and this appears to be correlated with neutralising antibody titers during the peri-infection period. While COVID-19 vaccinated cancer patients are also potentially likely to experience breakthrough infections, there is a lack of data on the extent to which such breakthrough infections occur among those with cancer and how, or if, this might be influenced by the different cancer sites.

For the present study, the US team turned to the TriNetX database which contains de-identified information on 90 million patients in the US. The team looked for vaccinated patients with one of 12 different cancers including pancreatic, liver, lung, colorectal, skin and thyroid and compared the level of breakthrough infections with a group of vaccinated, patients without any of the specified cancers. Data on age, sex, race and co-morbidities were collected for all patients and adjusted for in the analysis. The researchers examined the monthly incidence of breakthrough infections between December 2020 and November 2021 as well as the risk of hospitalisation and death among those infected.

COVID-19 vaccinated cancer patients and breakthrough infections

A total of 45,253 vaccinated cancer patients with a mean age of 68.7 years (53.5% female) were included in the analysis and matched with 591,212 vaccinated, non-cancer patients.

The cumulative risk of a breakthrough infection during the period of study among vaccinated COVID-19 cancer patients, was 13.6% which was higher than vaccinated, non-cancer patients, (Hazard ratio, HR = 1.24, 95% CI 1.19 – 1.29). Among the different cancer sites, the highest risk was for patients with pancreatic cancer (24.7%), followed by liver (22.8%), lung (20.4%) and colorectal (17.5%). The only cancer not associated with a significant increased risk for a breakthrough infection was thyroid (HR = 1.07, 95% CI 0.88 – 1.30) although the increased risk among patients with skin cancer was of borderline significance (HR = 1.17, 95% CI 0.99 – 1.38).

The risk of hospitalisation among cancer patients with breakthrough infections was much higher than matched, non-cancer patients (31.6% vs 3.9%, HR = 13.48). In addition, mortality risks were also significantly elevated (HR = 6.76, 95% CI 4.97 – 9.20).

The authors concluded that their results emphasised the need for those with cancer to maintain mitigation practices, especially given the emergence of COVID-19 variants for which vaccination might not provide full protection.

Wang W et al. Breakthrough SARS-CoV-2 Infections, Hospitalizations, and Mortality in Vaccinated Patients With Cancer in the US Between December 2020 and November 2021 JAMA Oncol 2022