COVID-19 Vaccines in Patients with Cancer: Long-Lasting Protection Revealed

Patients with cancer face heightened risks from COVID-19, but limited data exists on vaccine efficacy in this vulnerable group. Suboptimal immunogenicity and waning vaccine effectiveness have raised concerns about the protective benefits of COVID-19 vaccines in patients with cancer.

A prospective multicenter cohort study, published this week in JAMA Oncology, assessed the incidence rate of severe COVID-19 outcomes in patients with cancer based on the number of vaccine doses received and the potential waning of protection over time.

The Singapore-based study spanned 2 periods, the "Delta wave" (September 2021–December 2021) and the "Omicron wave" (January 2022–November 2022). Study participants included 73,608 patients with cancer (23,217 receiving active treatment; 50,391 cancer survivors) and 621,475 controls. The 2 cohorts were matched based on age, sex, race, ethnicity, and socioeconomic status.

The average age of patients with cancer, cancer survivors, and matched controls were 62.7, 62.9, and 61.8 years, respectively. Of the 73,608 patients with cancer, 36.9% were male and 81.6% were Chinese, 10.1% Malay, 6.2% Indian, and 2.0% represented other races and ethnicities.

The study observed impressive clinical effectiveness of mRNA-based vaccines against COVID-19 in patients with cancer. The incidence rate ratios (IRRs) for hospitalization and severe disease were significantly lower in the 3-dose and 4-dose groups compared to the 2-dose group during both waves. In the 3-dose group for active treatment, cancer survivors, and controls, IRRs were 0.14, 0.13, and 0.07 during the Delta wave and 0.29, 0.19, and 0.21 during Omicron wave, respectively.

For severe disease during the Omicron wave, the IRRs in the 3-dose and 4-dose groups were remarkably low, at 0.13, 0.10 and 0.10 for the active treatment, cancer survivors, and controls, respectively.

Of particular significance, no waning of vaccine effectiveness against hospitalization and severe disease was observed beyond 5 months after a third dose, and up to 5 months after a fourth dose. This suggests that actively treated patients with cancer, cancer survivors, and matched controls maintained protection against severe COVID-19 outcomes for an extended period after receiving the third or fourth vaccine dose.

This comprehensive cohort study provides compelling evidence of the clinical effectiveness of mRNA-based vaccines in patients with cancer. The findings demonstrate the longevity of immunity in preventing severe COVID-19 outcomes, even in the face of emerging variants.

These insights highlight the importance of timely vaccination efforts and emphasize the crucial role of vaccines in safeguarding vulnerable populations against COVID-19.