Expected Response to the Additional Fifth Dose of COVID‑19 Vaccine

Dear Editor, COVID‑19 is still a global emergency with no effective treatment.[1] Vaccination is the best option for managing the spread of this disease.[2] COVID‑19 vaccination is now universally acknowledged as an effective primary COVID‑19 preventive strategy. Traditionally, two vaccine doses are necessary for full vaccination. After complete vaccination, immunity levels may diminish, necessitating the use of self‑protective behavior. When there is a new developing variant and a potential decline in antibodies after completion of routine immunization, several experts recommend using an additional booster dose of the COVID‑19 vaccine.[3,4] In general, vaccine effectiveness against COVID‑19 infection wanes significantly 5‑8 months after completion of immunization, which is why COVID‑19 vaccine booster injections are required.