In regards to the ruling on vaccination or immunization:
Shaikh Yahya ibn Ali al-Hajoori [may Allah preserve him] was asked:
[Regarding] the issue of immunization and vaccination for children or some sick people or workers using a medical needle, is it allowed to do so, specifically if its success is affirmed? Is this considered puncturing the trust in Allah (Tawakul) because some people do not vaccinate their children nor respond to the government in its campaign for vaccination?
“I do not detest the one who vaccinates if he puts his trust in Allah. This does not contradict with the correct Tawakul. ‘Allamah Bin Baz rahimahullah passed the verdict that it does not contradict Tawakul. From the evidences for that is the statement of the Prophet (ﷺ):
مَنْ تَصَبَّحَ سَبْعَ تَمَرَاتٍ عَجْوَةً، لَمْ يَضُرُّهُ ذَلِكَ الْيَوْمَ سَمٌّ وَلاَ سِحْرٌ
“If Somebody takes seven ‘Ajwa dates in the morning, neither magic nor poison will hurt him that day.”
[Bukhari no. 5769]
So this is used for protection before a sickness and this Istidlaal [derivation of evidence from this Hadith] is good. So upon this, there is no harm upon the one who gets vaccinated and the one who does not vaccinate there is no detestation upon him. There is a verdict that opposes this verdict from Muhammad ibn Ibraahim Ala Shaikh rahimahullah. He said that vaccination is disliked and it is not unlawful due to the lack of evidence for its prohibition. It is only disliked due to it bringing sickness through the cure. They take some of the sickness then place it in a healthy body and this leads to some protection or sometimes leads to the swelling of the place which [the needle] enters or what is like that. So he said it is disliked but does not reach the level of haram and the first opinion of Ibn Baz rahimahullah is more correct due to the strength of his evidence. Verily the affair is that those who have experience are supposed to establish the immunization along with eagerness not to repeat what happens in some parts of Yemen where the cure for diabetes is given instead of the needle for immunization. So they kill a number of children, which is not something easy. It is from what scares the people in regards to their children”
[Al-Ajwibatur-Radiyyah ‘ala Asilatul-Tibiyyah pg. 25-26]
Faisal Ibn Abdul Qaadir Ibn Hassan
Note: You can read some of the speech of Mufti Shaikh Muhammad Ibn Ibraahim rahimahullah here.
This is also the view of Shaikh Ibnul-‘Uthaymeen rahimahullah that there is nothing wrong with vaccinating and that it does not affect putting ones trust in Allah. Rather he said it is from putting trust in Allah [See: Liqaa Bab as-Shahri no. 1]