There are a number of different, albeit related, questions intertwined here, so I’ll attempt to address them one by one. However, I’ll preface by saying that I’ll stick to these issues only, and not wander into the wider issue of Judaism and vaccination, which has already been addressed here: What Does Jewish Law Say About Vaccination?

It is also important to note that there are many different vaccines, and the methods and ingredients to manufacture them varies even between two vaccines created to combat a single disease.

We will start off with the question of non-kosher ingredients and work our way to the slightly more controversial issue of using a vaccine made with fetal tissue (often obtained from aborted fetuses).

Non-Kosher Ingredients in Vaccines and Medication

When it comes to non-kosher ingredients, in most instances the prohibition is limited to ingesting the substance orally. There is also no prohibition against benefiting from them. Thus, for example, although insulin contains substances derived from pigs, there is no issue for a diabetic to use it, since it is injected and not taken orally. The same is true for any vaccine or medication that is administered by suppository, enema, medicated bandage, etc. that may contain non-kosher ingredients.

Thus, Rabbi Chaim Ozer Grodzinski (1863–1940), one of the leading rabbis of the last century, writes that it would technically be permitted to feed a person non-kosher food through a tube inserted directly into the stomach.1

Notable exceptions to this principle are when the ingredients contain a mixture of milk and meat or non-kosher wine. In this instance, the prohibition includes deriving any benefit from it.2

(Even this medication or vaccination would presumably be allowed in a matter of life and death, pikuach nefesh. However, for the sake of this essay, let us assume that the need for vaccination has not yet risen to this level for the average person.)

Vaccine Made With Fetal Tissue

There are really two separate questions here:

a) Is it acceptable to use fetal tissue for scientific research and production of vaccines?

b) If the fetal tissue was already obtained (for argument’s sake, in an improper way) and used to create a vaccine, can I myself benefit from it?

Regarding the first question, without getting too much into the question of abortion and Jewish law, it is safe to say that there may indeed be some halachic issues with taking advantage of the tissue and other body parts of aborted fetuses.

Regarding the second question, it should be noted that for the most part, vaccines don’t actually contain any fetal tissue. Rather, in some instances a weakened virus is grown in cells strains from a fetus. The virus itself is then extracted from the cells and used in the vaccine.

Indeed, to this day, scientists are still using a cell strain that was obtained more than 50 years ago from a fetus. 3 Thus, even if one were to get this vaccine, that would in no way be encouraging anyone to perform abortions to harvest their cells.

It should be noted that most vaccines are researched and produced in ways that present no halachic questions at all. However, we must still address the few that may have been developed in ways that are contrary to halachah. May we benefit from them?

The very short and simple answer is, yes, it is permitted.

To quote Rabbi Dr. J. D Bleich in Contemporary Halachic Issues, vol. 4:

Although performance of an abortion is a grievous offense, Jewish law does not posit a "Miranda principle" or an exclusionary rule that would, post factum, preclude use of illicitly procured tissue for an otherwise sanctioned purpose...

By the same token, the absence of an exclusionary principle means that there is no moral barrier preventing the research scientist or the manufacturer of pharmaceutical products from utilizing fetal tissue procured by means of induced abortion for purposes that are otherwise moral, provided that such utilization of fetal tissue does not involve collusion in, or encouragement of, the abortion itself.

If an act (in this case, abortion) is forbidden, how can benefiting from it be permitted?

There are various instances in halachah4 that demonstrate that this is not an issue. Perhaps a simple analogy (although not quite the same) would be the prohibition of kilayim, crossbreeding various animals and fruits. Although producing and crossbreeding is biblically forbidden, if it was already done, one is permitted to benefit from it or even eat it (for example, there is no problem with eating a plumcot or riding a mule).5

In light of the above, even ingredients that we only have due to an abortion that was performed in the past don’t pose a halachic impediment to being vaccinated.

As in all cases of medical importance, everyone should seek and follow the advice of a trusted and qualified medical practitioner.