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Yang H, Xie Y, Li C. Understanding the mechanisms for COVID-19 vaccine's protection against infection and severe disease. Expert Rev Vaccines 2023; 22:186-192. [PMID: 36715150 DOI: 10.1080/14760584.2023.2174529] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
INTRODUCTION Multiple COVID-19 vaccines have been approved and employed in the fight against the pandemic. However, these vaccines have limited long-term effectiveness against severe cases and a decreased ability to prevent mild disease. AREAS COVERED This review discusses the relevant factors influencing the efficacy of the vaccines against mild and severe infection, analyzes the possible underlying mechanisms contributing to the different outcomes in terms of vaccine function and disease progression, and proposes improvements for the next generation of vaccines. EXPERT OPINION The reduced efficacy of the COVID-19 vaccine in the prevention of viral infection is closely related to the emergence of novel SARS-CoV-2 variants and their rapid transmission ability. Fundamentally, the immune responses induced by COVID-19 vaccines cannot effectively halt virus replication in the upper respiratory tract because only a limited number of specific antibodies reach these areas and decrease in concentration over time. However, the established immune response can provide sufficient protection against severe diseases by blocking viral infection of the lower respiratory tract or lung owing to sufficient antibody repertoires and memory responses. Considering this situation, future COVID-19 vaccines should have the potential to replenish the mucosal immune response in the respiratory tract to prevent viral infection.
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Affiliation(s)
- Huijie Yang
- Divsion of respiratory virus vaccines, National Institutes for Food and Drug Control, Beijing, China
| | - Ying Xie
- Institute of Medical Biology, Chinese Academy of Medical Science and Peking Union Medical College, Kunming, China
| | - Changgui Li
- Divsion of respiratory virus vaccines, National Institutes for Food and Drug Control, Beijing, China
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He H, Wang Y, Deng X, Yue C, Tang X, Li Y, Liu Y, Yin Z, Zhang G, Chen Z, Xie S, Wen N, An Z, Chen Z, Wang H. Immunogenicity of three sequential schedules with Sabin inactivated poliovirus vaccine and bivalent oral poliovirus vaccine in Zhejiang, China: an open-label, randomised, controlled trial. THE LANCET. INFECTIOUS DISEASES 2020; 20:1071-1079. [PMID: 32442523 DOI: 10.1016/s1473-3099(19)30738-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 09/25/2019] [Accepted: 12/02/2019] [Indexed: 01/12/2023]
Abstract
BACKGROUND The globally synchronised introduction of inactivated poliovirus vaccine (IPV) and replacement of trivalent oral poliovirus vaccine (OPV) with bivalent OPV (bOPV) were successfully implemented in China's routine immunisation programme in May, 2016. In response to the global shortage of Salk-strain IPV, Sabin-strain IPV production was encouraged to develop and use in low-income and middle-income countries. We assessed the immunogenicity of the current routine poliovirus vaccination schedule in China and compared it with alternative schedules that use Sabin-strain IPV (sIPV) and bOPV. METHODS This open-label, randomised, controlled trial recruited healthy infants aged 60-75 days from two centres in Zhejiang, China. Eligible infants were full-term, due for their first polio vaccination, weighed more than 2·5 kg at birth, were healthy on physical examination with no obvious medical conditions, and had no contraindications to vaccination. Infants were randomly assigned (1:1:1) using permuted block randomisation (block size of 12) to one of three polio vaccination schedules, with the first, second, and third doses given at ages 2 months, 3 months, and 4 months, respectively: sIPV-bOPV-bOPV (1sIPV+2bOPV group; current regimen), sIPV-sIPV-bOPV (2sIPV+1bOPV group), or sIPV-sIPV-sIPV (3sIPV group). The primary endpoint was the proportion of infants with seroconversion to each of the three poliovirus serotypes 1 month after the third dose. Serious and medically important adverse events were monitored for up to 30 days after each vaccination. We assessed immunity in the per-protocol population (all children who completed all three vaccinations and had pre-vaccination and post-vaccination laboratory data) and safety in all children who received at least one dose of study vaccine. This trial is registered with Clinicaltrials.gov, NCT03147560. RESULTS Between May 1, 2016, and Dec 1, 2017, we enrolled and randomly assigned 528 eligible infants to one of the three treatment groups (176 in each group); 473 infants (158 in the 1sIPV+2bOPV group, 152 in the 2sIPV+1bOPV group, and 163 in the 3sIPV group) were included in the per-protocol population. 100% seroconversion against poliovirus types 1 and 3 was observed in all three groups. Infants who received an immunisation schedule containing bOPV had significantly higher antibody titres against poliovirus types 1 and 3 than did the sIPV-only group (2048 in all three treatment groups; p<0·0001). Seroconversion against type 2 poliovirus was observed in 98 (62%) infants in the 1sIPV+2bOPV group, 145 (95%) infants in the 2sIPV+1bOPV group, and 161 (99%) infants in the 3sIPV group. No serious adverse events occurred during the study; 14 minor, transient adverse events were observed, with no significant differences across study groups. INTERPRETATION All three study schedules were well tolerated and highly immunogenic against poliovirus types 1 and 3. Schedules containing two or three sIPV doses had higher seroconversion rates against poliovirus type 2 than did the schedule with a single dose of sIPV. Our findings support inclusion of two sIPV doses in the routine poliovirus vaccination schedule in China to provide better protection against poliovirus type 2 than provided by the current regimen. FUNDING Chinese Center for Disease Control and Prevention and China National Biotec Group Company.
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Affiliation(s)
- Hanqing He
- Immunisation Programme Department, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, Zhejiang, China
| | - Yamin Wang
- National Immunisation Programme, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Xuan Deng
- Immunisation Programme Department, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, Zhejiang, China
| | - Chenyan Yue
- National Immunisation Programme, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Xuewen Tang
- Immunisation Programme Department, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, Zhejiang, China
| | - Yan Li
- National Immunisation Programme, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Yan Liu
- Immunisation Programme Department, Hangzhou Municipal Center for Disease Control and Prevention, Hangzhou, Zhejiang, China
| | - Zhiying Yin
- Immunisation Programme Department, Quzhou Municipal Center for Disease Control and Prevention, Quzhou, Zhejiang, China
| | - Guoping Zhang
- Immunisation Programme Department, Chun'an County Center for Disease Control and Prevention, Hangzhou, Zhejiang, China
| | - Zhongbing Chen
- Immunisation Programme Department, Longyou County Center for Disease Control and Prevention, Hangzhou, Zhejiang, China
| | - Shuyun Xie
- Immunisation Programme Department, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, Zhejiang, China
| | - Ning Wen
- National Immunisation Programme, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Zhijie An
- National Immunisation Programme, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Zhiping Chen
- Immunisation Programme Department, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, Zhejiang, China.
| | - Huaqing Wang
- National Immunisation Programme, Chinese Center for Disease Control and Prevention, Beijing, China.
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