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Pregnancy flu vaccination ‘effective’ at protecting babies, PHE study shows

Flu vaccination during pregnancy is effective in preventing infection and hospitalisation in babies, even when the main circulating strain differs from that in the vaccine, Public Health England research has shown. 

In 2013/14, analysis of babies born between September and April showed the flu vaccine was 66% effective against laboratory-confirmed cases.

A year later, when the flu season was dominated by a mismatched strain, the vaccine effectiveness fell but was still 50%, the research by PHE scientists and researchers at the London School of Hygiene and Tropical Medicine showed.

The analysis included 37 eligible infants with confirmed influenza in 2013/2014, and 81 in 2014/2015, of which 19% and 25% respectively had vaccinated mothers.

Of those, 30 babies in 2013/14 and 69 babies in 2014/15 had been hospitalised, researchers said.

When looking only at babies infected with the dominant influenza subtype in each season, vaccine effectiveness was even higher at 78% in 2013/14 and against circulating and 60% the following year, the researchers reported in the Journal of Infectious Diseases.

‘Our results over two influenza seasons provide further evidence that giving inactivated influenza vaccine to pregnant women is effective against laboratory-confirmed influenza infection and resulting hospitalizations in their young infants, even in a season with circulation of a drifted strain,’ the researchers concluded.

Dr George Kassianos, RCGP national immunisation lead, said flu vaccination in pregnancy was important for both mother and baby.

‘The best protection we can give to a neonate against influenza is mother’s antibodies induced by vaccination.’

He added: ‘It is never too late to vaccinate a pregnant woman against influenza. Even if the baby is born, vaccination of the mother (cocooning) reduces the risk of the neonate getting infected with influenza.’

‘During the last influenza season, 45% of pregnant women were vaccinated against influenza in England. I am pleased to see that 60% of pregnant women in the clinical groups at risk last flu season were vaccinated.

‘We need to continue making every effort to vaccinate pregnant women not only by providing education but also by facilitating vaccination at times working mothers or mothers that look after young children can attend our clinics for vaccination.’

Practices faced delays of the flu vaccine for 18-64-year-olds this year, following an unexpected delay in manufacturing. Child nasal spray flu vaccines have also been delayed, with GP practices told to only order vaccines one week at a time.