Can we violate Shabbos to inject a vaccine?

Question

Vaccines save lives. I'm not here to argue about that, take it somewhere else. If you don't agree, for the purposes of this question just imagine I'm talking about some medicine that accomplishes vaccination, but is magically safe from whatever invented danger that bothers you about it.

Vaccines save lives. However, they are not administered to treat a current illness -- they are given to prevent dangerous illnesses from coming.

Since we know that one may only violate Shabbos for a חולה שיש בו סכנה (patient who is in danger for his life) for things that have to do with saving that patient's life (see Rambam, Hilchot Shabbos 2 (English), Shulchan Aruch, Orach Chaim 328), if we would have to be מחלל שבת in order to administer vaccines¹, would we be allowed to violate Shabbos to administer vaccines?

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¹ It's debatable whether any injections are Biblical Shabbos transgressions, see שמירת שבת כהלכתה ch 32:58, and footnote 151 there; it appears that all agree that subcutaneous and intramuscular injections are not biblically prohibited. For the purposes of this discussion, let's assume that there is some universally agreed-upon Biblical transgression involved, such as driving a car in order to get it, or writing a prescription for it.

Answer 1

Shemiras Shabbas K'hilchasa 32:62 -- one is allowed to inject vaccines where there is a concern that the patient will become dangerously sick.

If a doctor feels that this is urgent, then even biblical transgressions such as driving a car or writing a script are allowed, where necessary.

In footnote 160, there, Rav Neuwirth cites what he wrote earlier, in footnote 60. There, he retells the story about Rabbi Yisrael Salant, who decided that one year (according to Wikipedia, 1848), nobody should fast on Yom Kippur, due to a concern for a cholera epidemic. However, Rav Neuwirth notes there (60) that one should try to do what needs to be done in a different way than usual (שינוי), where possible.

I may come back to update this answer more later, as I learn more information, but the recent rulings of Rav Asher Weiss (cited on Twitter here) about taking the new covid-19 vaccines on Shabbos are very relevant. Very briefly: Rav Weiss ruled that even if someone is given an appointment for the vaccine on Shabbos and, if the appointment is missed, will have their turn delayed for a while, one may not violate Biblical or Rabbinic prohibitions to receive the vaccine. However, someone who is eligible for the vaccine (eg in England right now, see the responsum dated 27 Kislev) is probably at higher risk and therefore is not worse than a חולה שאין בו סכנה, and may use אמירה לעכו"ם to receive the vaccine, especially since intramuscular injection does not include any Shabbos violation at all.

(See also https://youtu.be/CvdRqMiPfL4 for some more information from Rav Weiss about the halachos of the covid-19 vaccine in general. Especially ~43:20.)

Answer 2

The Noda Beyehuda (YO"D 210) writes that one may not dissect a Jewish corpse (which is forbidden) in order to discover the cause of death, even if it is the only way to uncover information that will help save lives in the future. He explains:

אבל בנידון דידן אין כאן שום חולה הצריך לזה רק שרוצים ללמוד חכמה זו אולי יזגמן חולה שיהיה צריך לזה, ודאי דלא דחינן משום חששא קלה זו שום איסור תורה או אפי׳ איסור דרבנן, שאם אתה קורא לחששא זו ספק נפשות א״כ יהיה כל מלאכת הרפואות שחיקת ובישול סמנים והכנת כלי איזמל להקזה מותר בשבת שמא יזדמן היום או בלילה חולה שיהיה צורך לזה... וחלילה להתיר דבר זה

Basically, unless there is a חולה who needs it, one cannot transgress any prohibition - even one of Rabbinic origin - on the off chance that it may save lives later.

The Chasam Sofer (Y"D 336) and Binyan Tzion (V1, §137) rules the same. (See also similar ruling in Shu"t R' Akiva Eiger §60, although marginally different)

[This may be the explanation why we are not obligated to all become doctors and learn emergency first aid, although this could potentially lead to saving lives in the future.]

However, the Chazon Ish (Y"D 207.6) writes that the deciding factor is not whether there is an existing חולה, but whether there is a reasonable belief that the action will save lives, and not just the 'off chance':

בפ"ת סי' שס"ג בשם הנו"ב והח"ס דאם יש חולה קמן מותר לנוולו משום פ"נ אבל אין חולה קמן אסור, ואין החילוק בין איתא קמן לליתא קמן, אלא אם מצוי הדבר דבזמן שמתריעין עלה [אף שאין בשעה חולה קמן] משום חולי מהלכת הו"ל כאויבים שצרו בעיר הסמוך לכפר וכדאמר בעירובין מ"ה א' ובתענית כ"א ב', ומיהו בשעת שלו' לא חשבינן ליה פ"נ אע"ג דשכיח בזמן מן הזמנים שיצטרכו לזה כמו שאין עושין כלי זיין בשבת בשעת שלו' דא"כ בטלת כל המצות, אלא לא מקרי ספק פ"נ בדברים עתידים שבהוה אין להם כל זכר, ובאמת שאין אנו בקיאים בעתידיות, ופעמים שמה שחשבונם להצלה מתהפך לרועץ, והלכך אין דנים בשביל עתידות רחוקות

Accordingly, if there is a likelihood that the administering of the vaccine will be effective in saving lives, one would be allowed to do anything necessary to make that possible.

(See also Shu"t Machane Chaim [V2 Y"D §60], who writes that the Chasam Sofer and Node Beyehuda were talking specifically about dissecting bodies because of the severity of kovod hames, but would not say this by other prohibitions. In his words:

רק ניכר כונת הנוב"י שחשש פן יחתכו כל המתים ללמוד מהם וגם ניכר כונת אדמו"ר (החת"ס) כי חשש על דברי הרמב"ן קללת אלקים תלוי וכו)

There are numerous sources where we find dispensations in Halacha משום שלום מלכות, although there was no specific סכנה yet. (See B"K 83a & Beis Yosef YD 178; Rambam Hil. Korban Pesach 3:1 and Kesef Mishne; Sanhedrin 26a [Tos. misherabu])

Summary: According to the pashtus of the Node Beyhuda and Chasam Sofer, it would be forbidden to do something for a future sakanah. However, the Chazon Ish explains that if there is a strong likelihood that this action will help save future lives, it is permitted.