本研究使用的疫苗

本研究使用的疫苗為乙型腦膜炎雙球菌複合疫苗 (保適腦 Bexsero)，是一種在香港註冊的處方藥物 (註冊編號: HK-66268)。其適應症為預防乙型腦膜炎雙球菌所引起的侵入性腦膜炎雙球菌疾病。給藥方式為肌肉注射。劑量為2劑，每劑0.5毫升，兩劑接種時間相隔不少於一個月。

副作用

施打疫苗時可能會因對針頭注射產生心理性反應而發生焦慮相關反應，包括血管迷走神經性反應(暈厥)、過度換氣或壓力相關反應。成人中最為常見的不良反應為注射部位疼痛、腫脹、發紅及不適、頭痛、噁心、肌肉痛、關節痛。

疫苗預防淋病的科學證據

淋病雙球菌 (Neisseria gonorrhoeae) 和乙型腦膜炎雙球菌 (Neisseria meningitidis) 同屬奈瑟菌屬 (Neisseria) ，基因組相似度約八至九成[1]。

在不同國家進行的回顧性數據分析均顯示疫苗可能對淋病提供某程度的保護。其中一項研究分析發現在全國推行接種乙型腦膜炎雙球菌複合疫苗後，乙型腦膜炎和淋病發生率皆明顯下降[2]。另一個紐西蘭的研究顯示接種該疫苗能減低淋病發生率約百分之三十一[3]，且能減少因淋病而住院的機會約百分之二十四[4]。美國的研究結果反映接種該疫苗比接種另一種腦膜炎雙球菌疫苗能減低淋病發生率約百分之四十六[5]；而另一個研究發現比較沒有接種乙型腦膜炎雙球菌複合疫苗的十六至二十三歲人士，已接種的人士的淋病盛行率減低了約百份之四十[6]。在澳洲，一項研究亦顯示該疫苗能對乙型腦膜炎雙球菌疾病提供百分之九十四至一百保護率，而對淋病則有約百分之三十二的保護率[7]。

有見及此，不同地方的研究團隊個別開展前瞻性臨床研究以探究乙型腦膜炎雙球菌複合疫苗對淋病的效用。澳洲一項研究採用隨機對照試驗形式，一半參加者接種疫苗，而另一半參加者接受生理鹽水注射，以判定該疫苗於減低男男性接觸者的淋病感染的效用[8]。在美國亦有另一個類似設計的隨機對照臨床試驗，分析該疫苗是否能於不同性別及社群中有效預防淋病感染[9]。法國一項隨機對照臨床研究採用開放試驗方式探討疫苗效用[10]，而他們於2023年初發布的初步結果顯示接種乙型腦膜炎雙球菌複合疫苗疫苗能減低約一半的感染風險，而且沒有顯著的安全風險[11]。

Vaccine being studied

The vaccine being studied is a four-component serogroup B meningococcal vaccine (Bexsero), which has been registered as a prescription drug in Hong Kong (registration number: HK-66268). Its indication is to prevent invasive disease caused by Neisseria meningitidis serogroup B. It is administered by two doses of intramuscular injection with 0.5mL each at least one month apart.

Adverse reactions

Anxiety-related reactions, including vasovagal reactions (syncope), hyperventilation or stress-related reactions may occur in association with vaccination as a psychogenic response to the needle injection. The most common solicited adverse reactions observed in clinical trials among adults included injection site pain, induration and erythema, malaise, fatigue, headache, nausea, myalgia, and arthralgia.

Scientific evidence on gonorrhoea prevention

Both Neisseria gonorrhoeae and Neisseria meningitidis belongs to the same genus Neisseria, sharing 80-90% genetic identity [1].

Multiple retrospective studies conducted in different countries found that MenB vaccine offered certain degree of protection against gonorrhoea. One of these studies found that the incidences of gonorrhoea and meningococcal disease decreased after a nationwide mass MenB vaccination campaign [2]. A study conducted in New Zealand showed that the vaccine could reduce the incidence of gonorrhoea by 31% [3], and prevent 24% hospitalization rate from gonorrhoea [4]. Results from an American study reflected that receiving MenB vaccine could reduce gonorrhoea incidence by 46% compared to another meningococcal vaccine [5]. Another American study showed that the prevalence of gonorrhoea reduced by 40% among vaccinated individuals aged between 16 and 23 years compared with unvaccinated ones [6]. In Australia, a study showed that the effectiveness of MenB vaccine against meningococcal disease and gonorrhoea was 94-100% and about 32%, respectively [7].

In view of these results, research teams around the world initiated prospective clinical trials to assess the protection offered by MenB vaccine against gonorrhoea infection. An Australian study adopted a randomised controlled trial design to determine the efficacy of the vaccine against gonorrhoea, with half of the participants received MenB vaccine and normal saline, respectively [8]. A similarly designed study is being conducted in the States among men and women at risk of gonorrhoea [9]. A French clinical trial adopted an open-label approach [10], and the interim results reported in early 2023 showed that receiving MenB vaccine could reduce about 50% risk of acquiring gonorrhoea without serious drug-related adverse events [11].

參考文獻 References

1. Gonococcal Vaccine Development: Lessons from Group B Meningococcal Vaccines. EBioMedicine. 2017 Aug;22:1. doi: 10.1016/j.ebiom.2017.07.026. PMID: 28802678; PMCID: PMC5552264.
2. Azze RFO. A meningococcal B vaccine induces cross-protection against gonorrhea. Clin Exp Vaccine Res. 2019 Jul;8(2):110-115. doi: 10.7774/cevr.2019.8.2.110. Epub 2019 Jul 31. PMID: 31406692; PMCID: PMC6689502.
3. Petousis-Harris H, Paynter J, Morgan J, Saxton P, McArdle B, Goodyear-Smith F, Black S. Effectiveness of a group B outer membrane vesicle meningococcal vaccine against gonorrhoea in New Zealand: a retrospective case-control study. Lancet. 2017 Sep 30;390(10102):1603-1610. doi: 10.1016/S0140-6736(17)31449-6. Epub 2017 Jul 10. PMID: 28705462.
4. Paynter J, Goodyear-Smith F, Morgan J, Saxton P, Black S, Petousis-Harris H. Effectiveness of a Group B Outer Membrane Vesicle Meningococcal Vaccine in Preventing Hospitalization from Gonorrhea in New Zealand: A Retrospective Cohort Study. Vaccines (Basel). 2019 Jan 5;7(1):5. doi: 10.3390/vaccines7010005. PMID: 30621260; PMCID: PMC6466174.
5. Bruxvoort KJ, Lewnard JA, Chen LH, Tseng HF, Chang J, Veltman J, Marrazzo J, Qian L. Prevention of Neisseria gonorrhoeae With Meningococcal B Vaccine: A Matched Cohort Study in Southern California. Clin Infect Dis. 2023 Feb 8;76(3):e1341-e1349. doi: 10.1093/cid/ciac436. Erratum in: Clin Infect Dis. 2023 Jan 11;: PMID: 35642527.
6. Abara WE, Bernstein KT, Lewis FMT, Schillinger JA, Feemster K, Pathela P, Hariri S, Islam A, Eberhart M, Cheng I, Ternier A, Slutsker JS, Mbaeyi S, Madera R, Kirkcaldy RD. Effectiveness of a serogroup B outer membrane vesicle meningococcal vaccine against gonorrhoea: a retrospective observational study. Lancet Infect Dis. 2022 Jul;22(7):1021-1029. doi: 10.1016/S1473-3099(21)00812-4. Epub 2022 Apr 12. PMID: 35427490.
7. Wang B, Giles L, Andraweera P, McMillan M, Almond S, Beazley R, Mitchell J, Lally N, Ahoure M, Denehy E, Koehler A, Flood L, Marshall H. Effectiveness and impact of the 4CMenB vaccine against invasive serogroup B meningococcal disease and gonorrhoea in an infant, child, and adolescent programme: an observational cohort and case-control study. Lancet Infect Dis. 2022 Jul;22(7):1011-1020. doi: 10.1016/S1473-3099(21)00754-4. Epub 2022 Apr 12. PMID: 35427492.
8. https://clinicaltrials.gov/ct2/show/NCT04415424
9. https://clinicaltrials.gov/ct2/show/NCT04350138
10. https://clinicaltrials.gov/ct2/show/NCT04597424
11. Jean-Michel Molina, Beatrice Bercot, Lambert Assoumou, Algarte-Genin Michele, Emma Rubenstein, Gilles Pialoux, Christine Katlama, Laure Surgers, Cecile Bebear, Nicolas Dupin, Jean-Paul Viard, Juliette Pavie, Claudine Duvivier, Jade Ghosn, Dominique Costagliola. ANRS 174 DOXYVAC: an open-label randomized trial to prevent STIs in MSM on PrEP. Conference on Retroviruses and Opportunistic Infections, Seattle, abstract 119, 2023.