衞生防護中心8月28日新公布有關流感疫苗接種，你知多少

香港衞生防護中心（CHP）剛剛於8月28日公佈2025/26 年度「季節性流感疫苗學校外展接種計劃」，並上載最新的同意書。本年度的革新安排，對學童、家長和高風險群組尤為重要。

什麼是「流感季節」？

不少人以為「季節性流感」中的「季節」是指春夏秋冬，甚至誤以為要「每季打一針」。事實上，醫學上的「流感季節」指的是一整年的流感流行週期。

在北半球（包括香港），新的流感疫苗會於夏季生產，秋季推出，覆蓋冬季的流感高峰期，並持續保護至翌年春季；在香港，希望保護可以延伸至夏季的第二波高峰。因此，每年秋季只需打一劑新的季節性流感疫苗，而不是一年四針。孩子需要多少劑？

根據 CHP 指引 

9 歲以下從未接種過流感疫苗的兒童：當季需要 兩劑，第二劑須與第一劑相隔最少四星期。 

• 9 歲以下曾經接種過流感疫苗的兒童：每年只需 一劑。 

• 9 歲或以上人士：每年只需 一劑。eHealth 登記與資助掛鈎為了推動電子健康紀錄（eHealth）的應用，本年度規定： 

• 18 歲或以上的資助申請人：必須先登記 eHealth，才能享有疫苗資助。

• 16 至 17 歲人士：可自行決定是否登記，即使不登記，仍可享有政府流感疫苗資助。

• 16 歲以下兒童：由父母或監護人作出決定。

噴鼻式流感疫苗（LAIV） 誰適合？誰不適合？噴鼻式減活流感疫苗（LAIV）為 2 至 49 歲人士提供了針劑以外的另一選擇，但有比較多不可使用的原因，以下有幾點家長需要特別留意：

1. 與其他減活疫苗的時間間隔：LAIV 必須與其他減活疫苗在 同一日接種，或相隔 最少 28 日。若在太短時間內接種，會造成免疫干擾，使第二種疫苗的保護力減弱，甚至需要重新接種。

2. 孕婦不可使用：孕婦應改用注射式滅活流感疫苗，這樣也能透過胎盤為嬰兒提供保護。 

3. 哮喘或有喘鳴病史的兒童不建議使用：任何年齡的哮喘患者都不建議使用噴鼻式疫苗，因可能誘發哮喘。特別是 2 至 4 歲在過去 12 個月內曾有喘鳴，或曾使用支氣管擴張劑（包括口服藥物及吸入式藥物） 的兒童，均不適合接種噴鼻式疫苗。

4. 免疫力減弱家庭：若接種者本人或直系同住家庭成員正處於免疫力減弱狀態（例如正在接受化療、器官移植、或長期使用免疫抑制劑），也不應接種噴鼻式疫苗，因為疫苗中的減活病毒有機會傳播並導致症狀性流感感染。 

5. 年齡限制：由於效果在 50 歲或以上人士中較低，因此僅建議 2 至 49 歲使用。

6. 正在服用阿士匹靈或水楊酸藥物的兒童及青少年，例如川崎症Kawasaki Disease病患者，不應使用噴鼻式流感疫苗，改用注射式。

流感疫苗的不同製造方法

現時流感疫苗主要有三種製造方式：

• 雞蛋培養法：最普遍，但可能因「雞蛋適應性突變」而與流行株有差異。 

• 細胞培養法：在細胞中培養病毒，減少依賴雞蛋。 

• 重組技術法：利用 DNA 技術，在細胞中表達 與世衛當季推薦株完全匹配的血凝素蛋白(HA)。這種疫苗完全不含雞蛋白，特別適合有嚴重蛋過敏的人士，並且抗原含量較高，對免疫力較弱的人士能提供更佳保護。

總結

流感疫苗是預防流感及其併發症的最有效方法。過去報章亦報道過未接種疫苗的兒童或青少年感染後出現腦炎等嚴重併發症甚至死亡。家長需明白，每年一劑疫苗一般足以覆蓋整個流感季節，並應根據孩子的年齡、健康狀況及醫生建議選擇合適的疫苗。及早在秋季接種，能確保孩子在冬、春高峰以及香港的夏季高峰期獲得保護。

English Version

2025/26 Seasonal Flu Vaccination: A Guide for Parents

The Centre for Health Protection (CHP) in Hong Kong has launched the 2025/26 School Outreach Vaccination Program (SIVSOP) and released updated consent forms on 28 August 2025. This year brings important updates that parents should understand to protect their children and families.

What Does “Flu Season” Mean?

Many people misunderstand the word “seasonal.” They think it refers to the four seasons—spring, summer, autumn, and winter—and some even assume that a flu shot is needed every few months, like changing clothes. This is a common misconception. In medicine, a “flu season” refers to one year-long cycle of influenza activity. In the Northern Hemisphere, including Hong Kong, a new flu vaccine is decided by WHO in spring, produced in summer and made available in autumn. It is designed to provide protection during the winter peak, continue through spring, and in Hong Kong, hopefully extend into the secondary summer peak. This means only one flu shot is needed each year, not four.

How Many Doses Are Needed?

• Children under 9 who have never received a flu vaccine: two doses this season, spaced at least 4 weeks apart.

• Children under 9 who have previously received one or more flu vaccines: one dose each year.

• Anyone aged 9 or above: one dose each year.

eHealth Registration and Subsidy

To encourage the use of electronic health records, this year’s policy has been updated as follows:

• Applicants aged 18 or above: must register with eHealth to receive the flu subsidy.

• Adolescents aged 16–17: may choose whether to register. Even if they do not register, they will still enjoy the government’s flu subsidy.

• Children under 16: the decision will be made by parents or guardians, and subsidy will still apply.

Nasal Spray Flu Vaccine (LAIV): Who Can and Cannot Take It

The live attenuated influenza vaccine (LAIV), delivered as a nasal spray, is available for healthy individuals aged 2–49 years. However, because it contains weakened live virus, there are more restrictions on who should not take it:

1. Spacing with Other Live Vaccines: LAIV must be given on the same day as another live vaccine, or at least 28 days apart. If given too close together, the second vaccine may have reduced effectiveness, and revaccination may be required.

2. Not for Pregnant Women: Pregnant women should receive the injectable inactivated vaccine, which also passes protective antibodies to the baby through the placenta.

3. Not for Asthma Patients or Children with Wheezing: People of any age with asthma should not use LAIV, as it may trigger asthma attacks. In particular, children aged 2–4 years who have had wheezing in the past 12 months, or who have used bronchodilators (including oral medicines or inhalers such as salbutamol), should not receive LAIV.

4. Not for Households with Weakened Immunity: If the recipient or their immediate household members have weakened immunity (such as those receiving chemotherapy, organ transplant, or long-term immunosuppressive treatment), LAIV should not be used, as it may rarely lead to symptomatic flu infection.

5. Age Limitation: Because effectiveness is lower in older adults, LAIV is recommended only for people aged 2–49 years.

6. Children and young people receiving aspirin or salicylate containing therapy (e.g. aspirin for Kawasaki Disease), should not use LAIV. Choose injectable flu vaccine instead.

Types of Flu Vaccines

Flu vaccines today are produced in several ways:

• Egg-based: The traditional method, using fertilized chicken eggs, though it may result in small changes compared to circulating strains.

• Cell-based: The virus is grown in laboratory cell cultures, reducing reliance on eggs.

• Recombinant: DNA technology is used to produce the haemagglutinin (HA) protein genetically matched to WHO-recommended strains in insect cells. Importantly, this type of vaccine contains no hen egg protein, making it especially suitable for adults with severe egg allergy. It also contains higher antigen levels, which may offer stronger protection for people with weaker immune systems.

Final Word for Parents

Flu vaccination is the most effective way to prevent influenza and its complications. Past outbreaks in Hong Kong have shown that unvaccinated children and adolescents can suffer from serious complications such as encephalitis or even death. Parents should understand that one shot per year is usually enough to cover the entire flu season. The choice between injection and nasal spray depends on age, health conditions, and medical advice. By arranging vaccination in autumn, families can ensure protection for their children during the winter and spring peaks, and also through Hong Kong’s summer flu wave.