Challenges in Emerging Vaccines and Future Promising Candidates against SARS-CoV-2 Variants

Table 3

Schedule for different COVID-19 vaccines.

Vaccine	Dose	Interval (days)	Booster requirement
ChAdOx1 nCoV-19 [76–81]	2	56–84	A first booster after 4–6 months of primary series.; Vaccine efficacy against asymptomatic and moderate SARS-CoV-2 infection gradually gets weak over time
Ad26.CoV2.S [81]	1	—	—
BBIBP-CorV [6] [82, 83]	2	21	A first booster after 4–5 months of primary series
BBV152-Covaxin [4] [84, 85]	2	28	A first booster after 4–6 months of primary series.; Vaccine efficacy against asymptomatic and moderate SARS-CoV-2 infection gradually gets weak over time
CoronaVac [86]	2	14	A first booster after 4–6 months of primary series.
mRNA-1,273 [7]	2	28	A first booster for the highest priority use group (after 4–6 months of primary series). A second booster after 4–6 months of the first booster dose
BNT162b2 [87]	2	21	First booster for highest priority group (after 4–6 months of primary series).; A second booster after 4–6 months of the first booster dose
Gam-COVID-Vac [88]	1	—	A first booster after 21 days of the primary dose
NVX-CoV2373 [89]	2	56 days	A first booster dose after 4–6 months of the initial series. A second booster dose is 4–6 months after the first booster dose