評估5-11歲兒童接種科興疫苗的成效與風險（三）

 

來自港大化學系博士Dr. K. Kwong的看法

 

兒童的免疫系統尚未成熟，因此難以預計身體對外物的反應。如果免疫系統反應不足，病毒就容易高速繁殖，後果難以估量；如果身體反應過於強烈，就會產生過敏反應，需要使用抗組織胺藥。

 

選擇不接種疫苗：

在身體強壯 + 有足夠休息下，如果兒童接觸到Omicron（通常只造成上呼吸道感染），很大機會只會有感冒症狀；但如果遇上Delta（容易造成下呼吸道感染），病情會相對嚴重，處理亦較為麻煩。

 

針頭打進血管時：

兩種疫苗均有危險性。當疫苗經血液進入身體器官，那些器官就會發生免疫反應，造成發炎；若發炎情況於血管發生，免疫複合物或造成血管堵塞，後果嚴重。

 

 

Bring Home Messages

 

就着科興疫苗對兒童防疫的成效及風險，以上陳列了不同研究發現/專家評價，各位可自行斟酌是否讓小朋友注射此疫苗，同時亦歡迎其他資訊的補足，或不足之處的指正，筆者不勝感激。

 

事實上，任何接觸病毒的機會亦能達至注射疫苗的效果，而發病與否在於免疫系統是否足夠強大（Paludan & Mogensen, 2022），繼而控制病毒擴散 & 消滅病毒。根據外國研究（Conti, M.G. et. al, 2021），即使是初生嬰兒，其免疫系統也能經由母乳餵哺（研究中的母親在分娩前後曾感染肺炎病毒）被間接教育去辨認 & 消滅肺炎病毒。

 

最後，文首及文中提及接種復必泰疫苗的建議。這些論述或揭示了在疫苗選擇和劑量上，靈活性其實比想像中高。兒童的免疫系統尚未發展成熟，因此與大人的防疫方向會有差異；在選擇疫苗時，不妨先參考更多有關疫苗比較的最新資訊。

 

 

Reference

 

明報（2021, Nov 16）【新冠疫苗】疫苗顧問專家委員會建議：3至17歲可打科興 復必泰門檻降至5至11歲（附兒童接種兩款疫苗副作用一覽）https://health.mingpao.com/%E7%96%AB%E8%8B%97%E9%A1%A7%E5%95%8F%E5%B0%88%E5%AE%B6%E5%A7%94%E5%93%A1%E6%9C%83%E5%BB%BA%E8%AD%B0-3%E8%87%B317%E6%AD%B2%E5%8F%AF%E6%89%93%E7%A7%91%E8%88%88-%E5%BE%A9%E5%BF%85%E6%B3%B0%E9%96%80/

 

CDC. (2022, Jan 11). Frequently Asked Questions about COVID-19 Vaccination in Children

. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/faq-children.html

 

CDC. (2022, Jan 7). Interim Clinical Considerations for Use of COVID-19 Vaccines Currently Approved or Authorized in the United States. https://www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html

 

CDC. (2022, Jan 11). Most Children and All Teens Can Get COVID-19 Vaccines

. https://www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html

 

Corum, J. & Zimmer, C. (2021, May 7). How the Sinovac Vaccine Works. The New York Times.

https://www.nytimes.com/interactive/2020/health/sinovac-covid-19-vaccine.html (Eng. ver.)

https://cn.nytimes.com/health/20201229/sinovac-covid-19-vaccine/zh-hant/(繁體中文版)

 

Conti, M. G., Terreri, S., Piano Mortari, E., Albano, C., Natale, F., Boscarino, G., Zacco, G., Palomba, P., Cascioli, S., Corrente, F., Capponi, C., Mirabella, M., Salinas, A. F., Marciano, A., De Luca, F., Pangallo, I., Quaranta, C., Alteri, C., Russo, C., Galoppi, P., … Carsetti, R. (2021).

Fernandes, E. G., López-Lopes, G., Silva, V. O., Yamashiro, R., Madureira, K., Gallo, J. F., Lindoso, J. A., Sato, H. K., de Araujo, N., Nerger, M., & Brigido, L. (2021). Safety and immunogenicity of an inactivated SARS-CoV-2 vaccine (CoronaVac) in inadvertently vaccinated healthy children. Revista do Instituto de Medicina Tropical de Sao Paulo, 63, e83. https://doi.org/10.1590/S1678-9946202163083

 

Han, B., Song, Y., Li, C., Yang, W., Ma, Q., Jiang, Z., Li, M., Lian, X., Jiao, W., Wang, L., Shu, Q., Wu, Z., Zhao, Y., Li, Q., & Gao, Q. (2021). 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. The Lancet. Infectious diseases, 21(12), 1645–1653. https://doi.org/10.1016/S1473-3099(21)00319-4

 

Ho, K.(2021, 16 Nov). Covid-19: Hong Kong medical experts suggest lowering age limit for Sinovac jabs to 3. Hong Kong Free Press. https://hongkongfp.com/2021/11/16/covid-19-hong-kong-medical-experts-suggest-lowering-age-limit-for-sinovac-jabs-to-3/

 

Immune Response of Neonates Born to Mothers Infected With SARS-CoV-2. JAMA network open, 4(11), e2132563. https://doi.org/10.1001/jamanetworkopen.2021.32563

 

Lee, P.(2022, 11 Jan). Covid-19: Hong Kong to extend Sinovac jabs to children aged 5, invisible Omicron transmission chains suspected. Hong Kong Free Press.
https://hongkongfp.com/2022/01/11/covid-19-hong-kong-to-extend-sinovac-jabs-to-children-aged-5-invisible-omicron-transmission-chains-suspected/

 

Lu, L., Mok, B. W. Y., Chen, L., Chan, J. M. C., Tsang, O. T. Y., Lam, B. H. S., … & To, K. K. W. (2021). Neutralization of SARS-CoV-2 Omicron variant by sera from BNT162b2 or Coronavac vaccine recipients. medRxiv. https://www.medrxiv.org/content/10.1101/2021.12.13.21267668v1#:~:text=Conclusions%20Omicron%20variant%20escapes%20neutralizing,lower%20COVID%2D19%20vaccine%20effectiveness.

 

Paludan, S. R., & Mogensen, T. H. (2022). Innate immunological pathways in COVID-19 pathogenesis. Science Immunology, 7(67), eabm5505.