Expected Additional Protection Rate against Omicron COVID-19 Infection and Death for the Fifth Dose of COVID-19 Vaccine: An Appraisal from an Endemic Area in Indochina

Objective: COVID-19 is still a global emergency with no effective treatment. Vaccination is the greatest option for disaster management. COVID-19 vaccination is now universally acknowledged as an effective primary COVID-19 preventive strategy. In the case of the introduction of a new strain, as well as the likely loss of public immunity following routine mass vaccination, some scientists are recommending a fifth dosage vaccine. Because the efficacy of the fifth vaccine dose is unknown, any investigation into its efficacy is intriguing. Materials and Methods: To evaluate an additional protection rate against omicron COVID-19 infection and death resulting from a fifth dose of COVID-19 vaccine, the authors of this study used a clinical model technique. Results: According to simulations, the fifth immunization dose can still enhance immunity and provide additional protection against omicron COVID-19 infection. Despite this, the fifth immunisation dose can still enhance immunity while providing no additional protection against omicron COVID-19 mortality. Conclusions: There is no additional benefit in terms of avoiding omicron COVID-19 death because just four vaccination doses are required to protect against mortality.