Assalamualaikum. I would like to ask on the ruling of taking covid-19 vaccine during Ramadhan. Does it invalidate fasting?
The ruling of taking the injection of covid-19 vaccine on the daytime of Ramadhan is permissible and does not invalidate fasting because the injection does not go through an open cavity.
All acts of worship are tied with its conditions and matters set by shara’ like obligatory conditions, invalidators, sunnah actions and etc. The same goes for the worship of fasting which is obligatory upon all Muslim individuals who already reaches puberty. Fasting is just like other acts of worship, it is sanctioned based on Allah SWT’s saying:
يَا أَيُّهَا الَّذِينَ آمَنُوا كُتِبَ عَلَيْكُمُ الصِّيَامُ كَمَا كُتِبَ عَلَى الَّذِينَ مِن قَبْلِكُمْ لَعَلَّكُمْ تَتَّقُونَ
O you who have believed, decreed upon you is fasting as it was decreed upon those before you that you may become righteous –
Surah al-Baqarah (183)
Coming back to the presented question, an issue arises regarding whether one’s fasting is invalidated or not if he takes the injection of covid-19 vaccine whilst fasting. There are four types of administration of a vaccine; intramuscular injection administers the vaccine into the muscle mass, intravenous injection administers the vaccine through the vein, intradermal injection administers the vaccine in the topmost layer of the skin and subcutaneous injection administers the vaccine into the subcutaneous layer above the muscle and below the skin. 
In discussing this issue, generally, actions that invalidate fasting are when the conditions of fasting are not fully fulfilled, or one of the requisites of fasting are missing like haid, nifas, inserting something into the body and etc. This is as mentioned in al-Mausu’ah al-Fiqhiyyah al-Kuwaitiyyah:
يَفْسُدُ الصَّوْمُ - بِوَجْهٍ عَامٍّ - كُلَّمَا انْتَفَى شَرْطٌ مِنْ شُرُوطِهِ، أَوِ اخْتَل أَحَدُ أَرْكَانِهِ، كَالرِّدَّةِ، وَكَطُرُوءِ الْحَيْضِ وَالنِّفَاسِ، وَكُل مَا يُنَافِيهِ مِنْ أَكْلٍ وَشُرْبٍ وَنَحْوِهِمَا، وَدُخُول شَيْءٍ مِنْ خَارِجِ الْبَدَنِ إِلَى جَوْفِ الصَّائِمِ
“Matters invalidate fasting in general, all matters which do not complete the conditions, or one of the requisites is missing like being an apostate, experiencing haid and nifas. Committing actions invalidating the fasting like eating, drinking and the like. The same goes for inserting something from outside of the body into the cavity of the one who fasts”
(Refer Al-Mausu’ah al-Fiqhiyyah al-Kuwaitiyyah, 28/29)
The scholars explain that among matters that invalidate fasting is inserting something into the body through open cavity like nostrils and mouth. This is as explained by Imam al-Nawawi in his book Raudah al-talibin:
مِنَ الْمُفْطِرَاتِ دُخُولُ شَيْءٍ فِي جَوْفِهِ - وَقَدْ ضَبَطُوا الدَّاخِلَ الْمُفْطِرَ بِالْعَيْنِ الْوَاصِلَةِ - الظَّاهِرُ إِلَى الْبَاطِنِ فِي مَنْفَذٍ مَفْتُوحٍ عَنْ قَصْدٍ مَعَ ذِكْرِ الصَّوْمِ
“Among the matters invalidate fasting is inserting something into the open cavity. The scholars have decided that inserting something into al-jauf (cavity) invalidates fasting when the ain (object) reaches, which is (from) the external point to the internal point through open cavity intentionally whilst fasting.”
(Refer Raudah al-Talibin, 2/356)
The same goes for injection containing nutrients or to fluid the body, so it invalidates fasting although the injection does not go through the open cavity. This is different from the opinions of the scholars as concluded in detail by Sheikh Hassan al-Kaf in his book al-Taqrirat al-Sadidah:
Meaning: The Ruling of Injection (on the daytime of Ramadhan): Permissible in the situations of dharurat (exigent), but the scholars have differing opinions on the invalidation of the fast into three opinions:
- The first opinion: Fasting is invalidated in an absolute manner because something enters the cavity (al-jauf).
- Second opinion: Fasting is not invalidated in an absolute manner because something enters the cavity (al-jauf) without going through the open cavity.
- Third opinion: In need of some detailing and it is the most sahih opinion: if the ingredient of the vaccine contains nutrition or food, then his fasting is invalidated, but if it does not contain any food, then the following aspects shall be observed:
- If the injection administers through the capillary into the cavity, which is the vein capillary, then fasting is invalidated
- If the injection administers through the muscle which is capillary not inside of the cavity, then fasting is not invalidated
(Refer: Al-Taqrirat al-Sadidah, pg. 352)
According to the opinion of Sheikh Yusuf al-Qaradhawi, this injection does not invalidate fasting even if the injection is administered on the daytime of Ramadhan because the injection is not included under the category of eating or drinking in the perspective of shara’. 
Coming back to the presented question and discussion, it can be concluded that the ruling of administering covid-19 injection on the daytime of Ramadhan is permissible and does not invalidate fasting because the injection does not go through an open cavity.
“Module 2: Types of Vaccine and Adverse Reactions” website of World Health Organization, accessed on 18th Mac 2021, https://vaccine-safety-training.org/route-of-administration.html
Al-Mausu’ah al-Fiqhiyyah al-Kuwaitiyyah, Wizarah Auqaf wa al-Syu’un al-Islamiah, Dar Sofwah Misr, 1404-1427H
Raudah al-Talibin wa ‘Umdah al-Muftin, Abu Zakaria Mahyuddin, Maktabah Islami Bairut, t.t
Al-Takrirat al-Sadidah fi al-Masail al-Mufidah, Hasan bin Ahmad al-Kaff, Dar Mirath al-Nabawi, 1423H
“Puasa dan Ubat”, website of MyHealth, accessed on 18th Mac 2021, http://www.myhealth.gov.my/puasa-dan-ubat/
“ استعمال الحقنة للصائم”, website of al-Qaradawi, accessed on 18th Mac 2021, https://www.al-qaradawi.net/node/3747