Much has been made by anti-vaxxers of the fact that most current vaccines are grown in cells derived from an aborted human fetus. Specifically, from a tiny amount (a few grams) of lung tissue taken from a female Caucasian fetus aborted at three months in the early 1960s in Sweden. These cells, known as WI-38 (WI for Pennsylvania’s Wistar Institute), have, according to Wikipedia, “prevented disease or saved the lives of billions of people. Vaccines produced in WI-38 include those made against adenoviruses, rubella, measles, mumps, varicella zoster, poliovirus, hepatitis A and rabies.”

In the early days of vaccine development, monkey kidney cells were used to grow and harvest potential viruses, because monkey cells reproduce much faster than human cells. The only human cell line used in vaccine research came, infamously, from the cervix of Henrietta Lacks, who suffered from cancer. (Infamously, because she wasn’t consulted.) Neither monkey kidney cells nor the “HeLa” cell line was perfect—monkey cells differ from human cells, and the human line was cancerous.

Leonard Hayflick, a scientist at the Wistar Institute, discovered that the “normal” (non-cancerous, human) WI-38 cells were ideal for vaccine research, that is, for growing most types of human virus. (The cells came from Sweden because limited abortion was legal there in the early 1960s, at a time when it was illegal in the US.) Following Hayflick’s lead, researchers worldwide now routinely infect descendants of the original Swedish cells (still called WI-38) with human viruses, which can then be cultured in huge quantities for use as vaccines.

As an aside—or perhaps as a central point if you oppose abortion on moral grounds—in 2005, the Vatican’s Pontifical Academy for Life delivered a favorable opinion on the use of WI-38 “in order to avoid a serious risk not only for one’s own children but also…for the health conditions of the population as a whole—especially for pregnant women.”

The Vatican’s wording is a useful reminder that vaccination is as much a social as a personal act. Many people, such as pregnant women, babies and some older folk, shouldn’t be vaccinated, so the rest of us—the “herd”—protects them with our vaccine-induced immunity. Like driving on the right and not contaminating public water systems, vaccination is for the public good, by which individuals surrender some personal freedom to benefit the community as a whole.

And look at this! Our populist president has frequently alluded to the mythical measles/mumps/rubella (MMR) vaccine-autism connection, even inviting Andrew Wakefield, the original and now-discredited proponent of the connection, to an inaugural ball. (You know, of course, that Wakefield received £50,000–claiming no conflict of interest!—for help in a shady lawsuit that relied on this putative connection.) Yet, a few days ago, DJT did a surprising turnaround: Children, he said, “…have to get the shots, the vaccinations are so important.”

They sure are. Measles is one of the most contagious diseases, as the 2014-15 Disneyland outbreak reminded us. Completely eliminated from the US in 2000, it’s now (May 5) present in 22 states, brought in by travelers from (especially) Israel, Ukraine, and the Philippines. Five in a hundred kids with measles will get pneumonia and two in a thousand will die.

Finally, if the Presidential about-face doesn’t convince any vaccine-waverers out there, may I suggest you wander through one of our old cemeteries, such as Ferndale or Loleta, checking the ages on the gravestones. Before vaccinations, clean water and antisepsis, every second or third child died before age five. That’s why.