Since the outbreak of COVID-19, China has been leading the world in vaccines research, providing a powerful tool for epidemic prevention. The domestic COVID-19 vaccine displays acceptable and efficient protection and safety in clinical trials and real world research. However, there are still many challenges for domestic vaccines due to uncertainty about the duration of protection and effec-tiveness against multiple variant strains. Using a homologous vaccine to enhance immunity is feasible to deal with the immediate situation, however, in the long run, it is necessary to speed up the development of multivalent and universal vaccines for COVID-19. At the same time scientific and standardized safety monitoring is necessary as a priority so as to accurately assess the long-term safety of domestic vaccines.

1.博鳌亚洲论坛研究院, 中国人民大学重阳金融研究院. 全球新冠疫苗应用图景报告[R/OL]. (2021-07-29) [2021-10-19]. http://www.rdcy.org/index/index/news_cont/id/689206.html.

2.Tao K, Tzou PL, Nouhin J, et al. The biological and clinical significance of emerging SARS-CoV-2 variants[J]. Nat Rev Genet, 2021, 22(12): 757-773. DOI: 10.1038/s41576-021-00408-x.

3.Jara A, Undurraga EA, González C, et al. Effectiveness of an inactivated SARS-CoV-2 vaccine in Chile[J]. N Engl J Med, 2021, 385(10): 875-884. DOI: 10.1056/NEJMoa2107715.

4.Wu Z, Hu Y, Xu M, et al. Safety, tolerability, and immunogenicity of an inactivated SARS-CoV-2 vaccine (CoronaVac) in healthy adults aged 60 years and older: a randomised, double-blind, placebo-controlled, phase 1/2 clinical trial[J]. Lancet Infect Dis, 2021, 21(6): 803-812. DOI:  10.1016/s1473-3099(20)30987-7.

5.Zhang Y, Zeng G, Pan H, et al. Safety, tolerability, and immunogenicity of an inactivated SARS-CoV-2 vaccine in healthy adults aged 18-59 years: a randomised, double-blind, placebo-controlled, phase 1/2 clinical trial[J]. Lancet Infect Dis, 2021, 21(2): 181-192. DOI: 10.1016/s1473-3099(20)30843-4.

6.Frenck RW Jr, Klein NP, Kitchin N, et al. Safety, immunogenicity, and efficacy of the BNT162b2 COVID-19 vaccine in adolescents[J]. N Engl J Med, 2021, 385(3): 239-250. DOI: 10.1056/NEJMoa2107456.

7.Al Kaabi N, Zhang Y, Xia S, et al. Effect of 2 inactivated SARS-CoV-2 vaccines on symptomatic COVID-19 infection in adults: a randomized clinical trial[J]. JAMA, 2021, 326(1): 35-45. DOI: 10.1001/jama.2021.8565.

8.Wu S, Huang J, Zhang Z, et al. Safety, tolerability, and immunogenicity of an aerosolised adenovirus type-5 vector-based COVID-19 vaccine (Ad5-nCoV) in adults: preliminary report of an open-label and randomised phase 1 clinical trial[J]. Lancet Infect Dis, 2021, 21(12): 1654-1664. DOI: 10.1016/s1473-3099(21)00396-0.

9.Yang S, Li Y, Dai L, et al. Safety and immunogenicity of a recombinant tandem-repeat dimeric RBD-based protein subunit vaccine (ZF2001) against COVID-19 in adults: two randomised, double-blind, placebo-controlled, phase 1 and 2 trials[J]. Lancet Infect Dis, 2021, 21(8): 1107-1119. DOI: 10.1016/s1473-3099(21)00127-4.

10.Han B, Song Y, Li C, et al. Safety, tolerability, and immunogenicity of an inactivated SARS-CoV-2 vaccine (CoronaVac) in healthy children and adolescents: a double-blind, randomised, controlled, phase 1/2 clinical trial[J]. Lancet Infect Dis, 2021, 21(12): 1645-1653. DOI: 10.1016/s1473-3099(21)00319-4.

11.Xia S, Zhang Y, Wang Y, et al. Safety and immunogenicity of an inactivated COVID-19 vaccine, BBIBP-CorV, in people younger than 18 years: a randomised, double-blind, controlled, phase 1/2 trial[J]. Lancet Infect Dis, 2021, S1473-3099(21)00462-X. DOI: 10.1016/s1473-3099(21)00462-x.

12.Melgoza-González EA, Hinojosa-Trujillo D, Reséndiz-Sandoval M, et al. Analysis of IgG, IgA and IgM antibodies against SARS-CoV-2 spike protein S1 in convalescent and vaccinated patients with the Pfizer-BioNTech and CanSinoBio vaccines[J]. Transbound Emerg Dis, 2021. DOI: 10.1111/tbed.14344.

13.Ibarrondo FJ, Fulcher JA, Goodman-Meza D, et al. Rapid decay of anti-SARS-CoV-2 antibodies in persons with mild COVID-19[J]. N Engl J Med, 2020, 383(11): 1085-1087. DOI: 10.1056/NEJMc2025179.

14.Mlcochova P, Kemp SA, Dhar MS, et al. SARS-CoV-2 B.1.617.2 Delta variant replication and immune evasion[J]. Nature, 2021, 599(7883): 114-119. DOI: 10.1038/s415 86-021-03944-y.

15.He Z, Ren L, Yang J, et al. Seroprevalence and humoral immune durability of anti-SARS-CoV-2 antibodies in Wuhan, China: a longitudinal, population-level, cross-sectional study[J]. Lancet, 2021, 397(10279): 1075-1084. DOI: 10.1016/s0140-6736(21)00238-5.

16.Roghani A. The influence of COVID-19 vaccination on daily cases, hospitalization, and death rate in Tennessee, United States: case study[J]. JMIRx Med, 2021, 2(3): e29324. DOI: 10.2196/29324.

17.Abbasi J. COVID-19 mRNA vaccines blunt breakthrough infection severity[J]. JAMA, 2021, 326(6): 473. DOI: 10.1 001/jama.2021.12619.

18.Bergwerk M, Gonen T, Lustig Y, et al. COVID-19 breakthrough infections in vaccinated health care workers[J]. N Engl J Med, 2021, 385(16): 1474-1484. DOI: 10.1056/NEJMoa2109072.

19.Li Q, Nie J, Wu J, et al. SARS-CoV-2 501Y.V2 variants lack higher infectivity but do have immune escape[J]. Cell, 2021, 184(9): 2362-2371.e9. DOI: 10.1016/j.cell. 2021.02.042.

20.Zhou D, Dejnirattisai W, Supasa P, et al. Evidence of escape of SARS-CoV-2 variant B.1.351 from natural and vaccine-induced sera[J]. Cell, 2021, 184(9): 2348-2361.e6. DOI: 10.1016/j.cell.2021.02.037.

21.Supasa P, Zhou D, Dejnirattisai W, et al. Reduced neutralization of SARS-CoV-2 B.1.1.7 variant by convalescent and vaccine sera[J]. Cell, 2021, 184(8): 2201-2211.e7. DOI: 10.1016/j.cell.2021.02.033.

22.Liu C, Ginn HM, Dejnirattisai W, et al. Reduced neutralization of SARS-CoV-2 B.1.617 by vaccine and convalescent serum[J]. Cell, 2021, 184(16): 4220-4236. e13. DOI: 10.1016/j.cell.2021.06.020.

23.Cao Y, Yisimayi A, Bai Y, et al. Humoral immune response to circulating SARS-CoV-2 variants elicited by inactivated and RBD-subunit vaccines[J]. Cell Res, 2021, 31(7): 732-741. DOI: 10.1038/s41422-021-00514-9.

24.Cox RJ, Brokstad KA. Not just antibodies: B cells and T cells mediate immunity to COVID-19[J]. Nat Rev Immunol, 2020, 20(10): 581-582. DOI: 10.1038/s41577-020-00436-4.

25.Wang Y, Xie Y, Luo J, et al. Engineering a self-navigated MnARK nanovaccine for inducing potent protective immunity against novel coronavirus[J]. Nano Today, 2021, 38: 101139. DOI: 10.1016/j.nantod.2021.101139.

26.Wu Y, Huang X, Yuan L, et al. A recombinant spike protein subunit vaccine confers protective immunity against SARS-CoV-2 infection and transmission in hamsters[J]. Sci Transl Med, 2021, 13(606): eabg1143. DOI: 10.1126/scitranslmed.abg1143.

27.Cohen J. New Chinese vaccine could bolster global arsenal[J]. Science, 2021, 374(6563): 12-13. DOI: 10.1 126/science.acx9214.

28.Zou X, Cao B. COVID-19 vaccines for children younger than 12 years: are we ready?[J]. Lancet Infect Dis, 2021, 21(12): 1614-1615. DOI: 10.1016/s1473-3099(21)00384-4.