Maternal vaccination and risk of hospitalization for Covid-19 among newborns

There is a correlation between vaccination in pregnancy and reduced hospitalization rate related to Covid-19 among children, particularly in infants younger than 6 months of age.

Many studies have shown that maternally derived anti-SARS-CoV-2 antibodies from vaccination or a previous infection are efficiently transferred to the child throw placenta. In particular, infants whose mothers were vaccinated during pregnancy have higher levels of antibodies and are more likely persistent at 6 months of age, compared to children whose mothers had SARS-CoV-2 infection during pregnancy.

It was also observed that antibody titers in the umbilical cord blood of the newborn are higher after vaccination against Covid-19, if this occurred during the second or early third trimester of pregnancy. This correlates with the observation of better efficacy in protecting against infection in children whose mothers were vaccinated with a full cycle after 20sg, compared to those whose mothers were vaccinated during the first 20sg. Pending further data showing more evidence about the better timing to which the vaccination cycle should be offered,  the indication not to postpone maternal vaccination in any case remains unchanged, to minimize the risk of serious maternal and fetal complications derived from a possible waiting behavior.

An interesting fact is linked to the lower rate of hospitalization and therefore to a possible better protection conferred by the vaccine against Covid-19 infection, during the "Delta period" compared to the "Omicron period". Despite this clinical evidence, there was still a moderate reduction (38%) in the risk of hospitalisation during the omicron period among children under 6 months of age whose mothers were adequately vaccinated.

Children under 6 months of age are not among those who can take advantage of vaccination, but they are among those who have the greatest risk of complications related to Covid-19 infection.

Vaccination in pregnancy can be a valid tool to ensure effective protection of children and for this reason it must be encouraged.

Reference

N.B. Halasa, S.M. Olson, M.A. Staat, M.M. Newhams, A.M. Price, P.S. Pannaraj et al. Maternal Vaccination and Risk of Hospitalization for Covid-19 among Infants. N Engl J Med 2022;387:109-19.  DOI: 10.1056/NEJMoa2204399