Pregnancy and influenza – new data shows death rate of 25% for those who get critically ill

Influenza has reached pandemic  proportions and the spike in flu activity is much earlier than expected this season. Widespread influenza is being reported in 43 states. Therefore it is timely to review the article in January’s Obstetrics and Gynecology concerning  severe influenza infection and pregnancy.

Epidemiologists from the Department of Public Health in California pulled the data on hospitalizations for pregnant women who were severely ill with influenza in the 2013-2014 flu season. They identified 17 pregnant women and 1 woman who had recently given birth who were critically ill with influenza. The mortality rate for severe influenza infection in pregnancy was a staggering twenty-five percent. There were also 3 cases of intrauterine demise (stillbirth) related to the death of the mother. Five neonates were also delivered prematurely (between 26 and 33 weeks) in an attempt to improve the outcome for the mother.

The 2012-2013 flu season had the greatest number of critically ill pregnant women with influenza since the pandemic of 2009 when 80 cases  of severe laboratory confirmed influenza were identified in pregnant/post partum women in California.

Pregnant women are at much greater risk of severe complications from influenza, this fact is indisputable. Pregnant women account for 1% of the population of the United States population yet they make up 5% of the country’s influenza related deaths. Then of course there are the risks of bad outcomes for a baby whose mother is ill from influenza during pregnancy including premature delivery and growth restriction

Despite the severity of influenza during pregnancy vaaccine uptake remains low – only 50% or so of pregnant women get their annual flu vaccine. Even in years when the vaccine coverage isn’t as optimal (like this year) the vaccine still reduces the risk of influenza and the killed virus vaccine (a.k.a the flu shot) is safe in pregnancy and recommended (the nasal mist is not recommended because it has live virus).  In the recent California study 14 of the 18 pregnant women who required intensive care admission with influenza had not been vaccinated against the flu (only 1 had been vaccinated and the vaccine status of 3 was unknown).

So how can pregnant women protect themselves? Frequent hand washing/alcohol based hand sanitizers and the flu vaccine are front line protections. If your OB or midwife doesn’t recommend the flu shot you are seeing someone who is practicing outside the standard of care and perhaps you should wonder what other aspects of their practice are out of date or deviate from nationally vetted safety standards.  In my opinion it is malpractice to not recommend the flu vaccine to pregnant women.

In addition, flu-like symptoms should be reported immediately to a doctor and antiviral medication should be started as soon as possible without waiting for the results of testing. Pregnant women who receive antiviral medications within the first 2 days of getting sick were are far less likely to die than those treated later or not at all. These medications seem safe in pregnancy (there is good 5 year follow up data).

While no vaccine is perfect, considering how severe influenza can be for pregnant women any reduction in risk is important.

The California data is a case series, so it may be incomplete. There are false negatives for influenza testing and so some severe flu cases may have been unrecognized or unreported. However, the data is in line with previous reports.

What does this study add? It confirms that influenza is especially dangerous for pregnant women and that when pregnant women get critically ill with the flu the risk of death is high, supporting the recommendation of universal vaccination for pregnant women and early treatment with antivirals. The added benefit of vaccination in pregnancy is that is reduces the risk of influenza in the newborn.

If you are pregnant, get vaccinated against the flu. If you aren’t pregnant, get vaccinated because many people who get seriously ill have no risk factors and you never know when you will be around a pregnant woman, a newborn, or another person who is at increased risk for death due to the flu.