No, vitamin K is not a vaccine and is not lethal for newborns

Context

Several posts on Facebook (archived here, here, and here) with hundreds of views claim that the vitamin K shot is one of the most dangerous vaccines being administered to newborns and can cause death. The posts also claim its ingredients are toxic, and the black box label indicates its lethality.

However, these claims are false. 

In fact

Vitamin K is a fat-soluble vitamin essential for blood coagulation, clotting, and healing wounds.

Babies are born with very low vitamin K levels because the placenta is impermeable to this vitamin, and breast milk only contains trace amounts. Therefore, mothers cannot take supplements to ensure they pass vitamin K on to their babies during pregnancy or breastfeeding. A 0.5mg or 1.0mg vitamin K shot is strongly suggested by doctors to parents whose babies are displaying signs of a life-threatening medical condition called Vitamin K deficiency bleeding (VKDB), which has a 20 percent mortality rate. Newborns who are not administered the vitamin K shot are 81 times more likely to experience severe, possibly fatal, bleeding than those who do get the shot. It is not a vaccine.

Babies only start producing vitamin K once they ingest solid foods at around six months of age. However, by this time, it is already too late if they have deficiency bleeding as it may have traveled into their brain or intestines, requiring blood transfusions or surgeries, or in the worst cases, may result in death.

The ingredients of this shot are there to facilitate its injection and absorption in the body, mainly to make it a fluid. It also contains a preservative called benzyl alcohol, which is found in many other medications whose anesthetic properties reduce the discomfort at the injection site, such as antibiotics, anti-inflammatory, or antipsychotic medicines. There is no evidence that these ingredients are toxic, and it is safe for newborns.

The black box warning is there for the specific and unfortunate cases when patients suffering from significant bleeding who are being treated with anticoagulants are given such substantial doses of this shot through IV that it may result in anaphylaxis. This does not apply to babies since they have such low amounts in their blood and are only administered minor doses to prevent deficiency bleeding.

Two patients experienced anaphylaxis with IV having a 95 percent confidence interval of 0.04-11 per 10,000 doses. There is only one non-fatal reported case of anaphylaxis after a baby had their vitamin K shot in 2014 in Turkey. With more than four million shots being administered to newborns in the U.S. each year, no reports of anaphylaxis have been recorded there.

The verdict

Vitamin K is not a vaccine and does not cause death in newborns. It is administered if babies are showing signs of vitamin K deficiency to prevent fatal bleeding into vital organs.