If flu season falls during pregnancy, get one shot of inactivated influenza vaccine; any stage of pregnancy is fine; do not use the nasal spray

Pregnant people who get flu are more likely to be hospitalized than people who are not pregnant. One flu shot in pregnancy cuts your own flu hospitalizations by about four tenths. In the child’s first 6 months, confirmed flu falls by about half, and flu hospitalizations by about seven tenths. No rise in miscarriage, stillbirth, or birth defects was seen after the shot.

Cost

Self-pay, a few dozen to a little over 100 yuan per shot. One trip to a community vaccination clinic. The hard part is picking a product whose package insert does not list pregnancy as a contraindication

Benefit

The WHO 2022 position paper pooled existing studies. Pregnant people with flu had about 7 times the hospitalization risk of people who were not pregnant (OR 6.8, 95% CI 6–7.7, the plausible range). A trial in Bangladesh randomized 340 pregnant women into two groups. One got inactivated influenza vaccine; the other got pneumococcal vaccine as a control, followed to 24 weeks after the child was born. In the flu-vaccine group there were 6 confirmed flu cases in children versus 16 in controls, vaccine efficacy 63% (95% CI 5–85). Mothers’ own fever plus respiratory illness fell 36% (95% CI 4–57). Two South African trials used placebo; neither doctors nor pregnant women knew which shot was which. Among pregnant women without HIV, confirmed flu fell from 3.6% to 1.8%, efficacy 50.4% (95% CI 14.5–71.2). Their children fell from 3.6% to 1.9%, efficacy 48.8% (95% CI 11.6–70.4). Pooling 4 trials and 3 observational studies, confirmed flu in children under 6 months was about 48% lower (95% CI 33–59). Four observational studies looking at child hospitalization for confirmed flu found about 72% lower (95% CI 39–87). Another pool of only two trials found confirmed flu 34% lower (95% CI 15–50). But children’s “influenza-like illness” did not differ — that is illness that looks like flu without lab confirmation. Pregnant people’s own hospitalizations were read from records in four countries from 2010 to 2016. Hospitalization for confirmed flu was about 40% lower among those vaccinated (95% CI 12–59). On safety, one pool took in 40 studies. Stillbirth after vaccination aOR 0.84 (0.65–1.08), congenital malformation 1.03 (0.99–1.07). Both differences sat within error. Preterm birth 0.87 (0.78–0.96), about 13% lower. The US checked three flu seasons from 2012 to 2015. Vaccination in the 28 days before miscarriage aOR 0.9 (0.6–1.5), no association. The Chinese CDC’s 2026–2027 season guideline lists pregnant people as a priority group. It says vaccination at any stage of pregnancy can protect infants under 6 months of age, with a better effect in late pregnancy. Live attenuated vaccine is forbidden in pregnancy

Notes

Controversial. A 2017 US study found more miscarriages among people vaccinated in the 28 days before miscarriage (aOR 2.0, 1.1–3.6). The excess appeared only in those who had also received an H1N1-containing vaccine the prior season. The authors themselves said this does not prove causation. The same group later checked three more flu seasons and did not see the link again, so countries still say any stage of pregnancy is fine. Some domestic flu vaccine inserts still list pregnancy as a contraindication. Guidelines advise picking a product whose insert does not list pregnancy as a contraindication, and telling the vaccinator you are pregnant. Use only injectable inactivated vaccine. The nasal spray is live attenuated vaccine; domestically it is only for ages 3 to 17, and pregnant people must not receive it. Best to finish before the local flu season starts, usually September to October. If you miss that window, you can still catch up through the whole flu season. Children under 6 months cannot get flu vaccine, so this pregnancy shot is the main protection for the child’s first months. People who live with you and who care for the child are also a priority group; the adult account of flu vaccination is in Section 1, Item 20 (get a flu vaccine). The Benefit line has no mortality figures; the benefit magnitude is set by confirmed flu and hospitalization, with the reasoning in the verification record. The benefit falls on you and your child

Sources · 9

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