Passive immunity

[4] In humans, maternal antibodies (MatAb) are passed through the placenta to the fetus by an FcRn receptor on placental cells.

Immunization is often required shortly following birth to prevent diseases in newborns such as tuberculosis, hepatitis B, polio, and pertussis, however, maternal IgG can inhibit the induction of protective vaccine responses throughout the first year of life.

[7] Protection mediated by IgA is dependent on the length of time that an infant is breastfed, which is one of the reasons the World Health Organization recommends breastfeeding for at least the first two years of life.

It can be diagnosed by measuring the amount of IgG in a newborn's blood, and is treated with intravenous administration of immunoglobulins.

[citation needed] A preprint suggested that (SARS-CoV-2) antibodies in or transmitted through the air are an unrecognized mechanism by which, transferred, passive immune protection occurs.

[11][better source needed] Artificially acquired passive immunity is a short-term immunization achieved by the transfer of antibodies, which can be administered in several forms; as human or animal blood plasma or serum, as pooled human immunoglobulin for intravenous (IVIG) or intramuscular (IG) use, as high-titer human IVIG or IG from immunized donors or from donors recovering from the disease, and as monoclonal antibodies (MAb).

[14][15] There is also a potential risk for hypersensitivity reactions, and serum sickness, especially from gamma globulin of non-human origin.

[18] By 1896, the introduction of diphtheria antitoxin was hailed as "the most important advance of the [19th] Century in the medical treatment of acute infective disease".

[6] IVIG treatment was also used successfully to treat several patients with toxic shock syndrome, during the 1970s tampon scare.

Antibody prophylaxis of both hepatitis A and B has largely been supplanted by the introduction of vaccines; however, it is still indicated following exposure and prior to travel to areas of endemic infection.

Only one of the eight infected patients died, compared to a typical 80% Ebola mortality, which suggested that antibody treatment may contribute to survival.

It is rarely used in humans, and requires histocompatible (matched) donors, which are often difficult to find, and carries severe risks of graft-versus-host disease.

[18] In addition to conferring passive immunities, breastfeeding has other lasting beneficial effects on the baby's health, such as decreased risk of allergies and obesity.