Influenza

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What is flu, and why do we care about it in pregnancy? 

  1. We reviewed the flu vaccine in pregnancy previously, but we have never talked specifically about flu itself! 

    1. Flu is a contagious respiratory illness caused by the influenza virus 

    2. The virus is a negative sense RNA virus 

    3. There are multiple strains, including A, B, C, D

      1. We have probably heard about A and B, but C and D also can infect people 

        1. A and B are known to cause more severe illness, while C can cause can cause a mild infection 

        2. D can infect humans, but is not known to cause illness 

    4. Transmission is through aerosols and contaminated surfaces 

  2. Why do we care about flu so much? 

    1. In typical years, as much as 5-15% of the population will contract flu

    2. This leads to 3-5 million severe cases annually and up to 650,000 flu deaths a year in the world 

    3. In the US, on average, 8% of the population gets sick from the flu, per the CDC 

  3. Who is most likely to get sick? 

    1. Children are most likely to get sick from flu and people 65 and older are least likely to get sick 

    2. However, pregnant and postpartum individuals are at significantly higher risk of serious complications related to seasonal and pandemic influenza infections compared to non pregnant people 


How is flu prevented? 

  1. Vaccination 

    1. The CDC recommends that all adults receive an annual influenza vaccine and that individuals who are pregnant during the season receive an inactivated or recombinant influenza vaccine as soon as possible 

    2. Timing: end of October is ideal, but any time during flu season vaccination should be encouraged 

    3. Remember that it is safe to give the flu vaccine with other inactivated vaccines that may be needed in pregnancy (ie. Tdap, RSV, or COVID vaccines) 

    4. It is also safe for lactating individuals to receive the flu vaccine 

    5. Of note, the vaccine also benefits the newborn when it is given during pregnancy 

      1. Randomized controlled trials and observational studies have shown neonatal protection from maternal influenza vaccination 

    6. Importantly, studies show that when recommendations for the flue vaccine during pregnancy come from the patient’s Ob/Gyn or other obstetric health professional, and the vaccine was available in the office, the odds of vaccine acceptance and receipt are 5x-50x higher! 

    7. For more information on the flu vaccine, check out our previous episode: https://creogsovercoffee.com/notes/2019/5/26/vaccines-i-tdap-and-influenza

  2. Masks 

    1. This is probably familiar to all of us now with the COVID-19 pandemic 

    2. Mask wearing can help prevent transmission of many respiratory infections, particularly when community levels of circulating viruses are elevated 

    3. When to wear a mask 

      1. Local public health guidance and recommendations based on community-centered risks 

      2. Individual’s specific vulnerability due to health conditions 

      3. Clinical and health care professional recommendations 

  3. Other methods 

    1. Hand washing 

    2. Cleaning surfaces regularly 

    3. Make sure to to use usual techniques to minimize contamination/spread of disease 


How should we evaluate for influenza in pregnancy? 

  1. Assess for symptoms 

    1. Fever >100.4 F (38 C) and one of the following 

      1. Cough, runny nose, sore throat, headache or body aches, fatigue, difficulty breathing or SOB 

    2. If these symptoms are present, test for COVID and flu 

    3. Also assess for illness severity 

      1. Difficulty breathing or shortness of breath 

      2. Chest pain/pressure 

      3. Unable to keep down liquids 

      4. Dehydration signs and symptoms 

      5. Less responsive, confused

      6. Symptoms are worsening 

    4. If yes to any of the above, then encourage patient to go to emergency room or equivalent location to be treated 

    5. If no, if there are other morbidities (ie. cardiovascular or pulmonary issues, immunosuppression, obstetric issues like preterm labor) → should be seen in a clinical setting as moderate risk 

    6. Otherwise, patient is considered low risk and patient can be treated outpatient or even over the phone, with follow up in 24-48 hours 


How to Treat Respiratory Infection in Pregnancy 

  1. Empiric treatment 

    1. Oseltamivir is the preferred treatment for pregnant individuals 

      1. Dosing: 75 mg orally twice a day for 5 days 

    2. Zanamivir can also be used (two 5 mg inhalations twice daily for 5 days) 

    3. Peramivir can also be given, but is 1 dose IV for 15-30 min 

    4. Do not delay treatment while respiratory infection test is running

  2. If suspected to have both COVID and flu, oseltamivir and Paxlovid can be prescribed and taken together 

  3. Post Exposure chemoprophylaxis for flu 

    1. Due to high potential for morbidity and mortality related to flu in pregnant and postpartum individuals, post exposure chemoprophylaxis can be considered for those who are pregnant and for those who are up to 2 weeks postpartum 

    2. Recommendation: oseltamivir 75 mg 1x/day for 7 days 

    3. Should be started within 48 hours of most recent exposure 

    4. At risk family members of patients with flu should be referred to health care professionals for consideration of chemoprophylaxis