A reluctance to be vaccinated against COVID-19 persists in some population groups, raising fears of infection among pregnant women. Yet the evidence in favour of the vaccines’ safety and efficacy continues to grow.
With many countries still struggling to control the rapid spread of the COVID-19 virus – particularly the Delta variant – a reluctance to be vaccinated persists among some of the general population, despite the unequivocal benefits of the vaccine. Recent data from France’s biggest 30 hospitals indicate that every single covid patient in intensive care at the time had not been vaccinated. The story from reports from Greece was similar. Yet vaccine hesitancy persists.
As a result, governments in Greece, Italy and Australia have moved to make vaccination obligatory for certain professional groups, notably those working in healthcare and care homes. Yet it was such a proposal in France, to make vaccination compulsory for healthcare workers, that drew protestors to the streets of Paris and other French cities. With only minority proportions of some
populations fully vaccinated, some governments are similarly taking a coercive approach.
Others, like the UK, weary of lockdowns and anxious to see an economic rebound, are easing their social restrictions, apparently behind the security of a high vaccination rate. Yet the UK’s Royal College of Obstetricians and Gynaecologists has expressed its concern that the combination of relaxed restrictions, increasing prevalence of COVID-19 and vaccine hesitancy will lead to a further increase in infections among pregnant women.(1)
Behind the RCOG’s expression of concern lies new data from the UK’s Obstetric Surveillance System showing that one in ten pregnant women admitted to hospital with symptoms of COVID-19 needed intensive care. Moreover, it’s twice as likely that babies of pregnant women with symptoms of COVID-19 will be born prematurely. Other recent studies have also found that pregnant women who tested positive for COVID-19 at the time of birth were more likely to develop pre-eclampsia, need emergency delivery and had higher rates of stillbirth – although, as the RCOG pointed out, the absolute increases remain low.
The RCOG’s latest statement was the cue to urge all women who are pregnant or considering pregnancy ‘to seriously consider getting the vaccine’ or arranging a second dose as soon as possible.
The RCOG’s positive note echoes early and continuing guidance from the USA, which even at the beginning of the pandemic had identified pregnancy as a risk factor for serious COVID infection.(2) Yet, as the RCOG now acknowledges, its upbeat advice follows many months of mixed messages about the virus and the effect of vaccines in pregnancy. Notable among these messages was that the vaccines had never been studied in pregnant women and that the mRNA versions in particular may cause infertility by cross-reacting with a human placental protein and damage the placenta.
However, since those first messages pregnant women have now been included in the formal clinical trials of the vaccines, while a new retrospective study of 15,000 pregnant women in Israel either vaccinated or not with the Pfizer-BioNTech mRNA vaccine found a significantly lower rate of SARS-CoV-2 infection in the vaccinated group than in the non-vaccinated – with an efficacy rate of 78%.(3) The rollout of COVID-19 vaccines across the world (especially in Israel) and the decision of many pregnant women to be vaccinated has enabled this kind of real-world data analysis.
Secondly, the infertility myth was largely debunked in June in a New England Journal of Medicine report of pregnancy outcomes in more than 35,000 American women registered with a CDC smartphone-based surveillance system for the COVID-19 vaccination programme.(4) Preliminary results from this study – of mRNA vaccine safety in pregnancy – revealed a miscarriage rate no higher than in the general US population, although this finding too was subject some fake-news interpretation. ‘Preliminary findings did not show obvious safety signals among pregnant persons who received mRNA Covid-19 vaccines,’ wrote the authors.
Similarly, there is mounting evidence that the mRNA vaccines are safe for lactating mothers and their infants. First, a just-published University of California analysis of post-vaccination breast milk samples from seven breast-feeding women found no trace of vaccine-associated mRNA in 13 samples collected.(5) ‘These results provide important early evidence to strengthen current recommendations that vaccine-related mRNA is not transferred to the infant and that lactating individuals who receive the COVID-19 mRNA-based vaccine should not stop breastfeeding,’ concluded the authors.
And earlier this year a prospective study of 131 reproductive-age vaccine recipients (84 pregnant, 31 lactating, and 16 non-pregnant) found that mRNA vaccines generated ‘robust humoral immunity’ in pregnant and lactating women, with immunogenicity similar to that observed in non-pregnant women. Indeed, vaccine-induced immune responses were significantly greater than the response to natural infection.(6) A later study also found that the mRNA vaccine was immunogenic in pregnant women, with vaccine-derived antibodies transported to infant cord blood and breast milk.(7)
The case for vaccination in pregnancy seems apparently strong; the WHO continues to support it and recommends that mothers continue to breastfeed after vaccination. And there is now even a suggestion that breast-fed babies derive some protection against COVID-19 from maternal antibodies in breast milk. This, noted a news report in the journal Nature, is ‘the million dollar question at the moment’, and, while the vaccines do not pass through breast milk, antibodies seem to do.(8)
1. See https://www.rcog.org.uk/en/news/covid-unlocking-will-create-perfect-storm-for-pregnant-women-say-maternity-colleges/
2. See https://www.cdc.gov/coronavirus/2019-ncov/vaccines/recommendations/pregnancy.html
3. Goldshtein I, Nevo D, Steinberg DM, et al. Association between BNT162b2 vaccination and incidence of SARS-CoV-2 infection in pregnant women. JAMA 2021; doi:10.1001/jama.2021.11035
4. Shimabukuro TT, Kim SY, Myers TR, et al. Preliminary findings of mRNA Covid-19 vaccine safety in pregnant persons. N Engl J Med 2021; 384: 2273-2282.
5. Golan Y, Prahl M, Cassidy A, et al. Evaluation of messenger RNA from COVID-19 BTN162b2 and mRNA-1273 vaccines in human milk. JAMA Pediatr 2021; e211929.
6. Gray KJ, Bordt EA, Atyeo C, et al. Coronavirus disease 2019 vaccine response in pregnant and lactating women: a cohort study. Am J Obstet Gynecol 2021; S0002-9378(21)00187-3. doi:10.1016/j.ajog.2021.03.023.
7. Collier AY, McMahan K, Yu J, et al. Immunogenicity of COVID-19 mRNA vaccines in pregnant and lactating women. JAMA 2021; 325: 2370-2380. doi:10.1001/jama.2021.7563.
8. See https://www.nature.com/articles/d41586-021-01680-x