2013-14 Influenza Season Continues Apace

AAFP, CDC, Other Groups Reiterate Call to Immunize Pregnant Patients

February 04, 2014 01:23 am News Staff

With 38 states still reporting widespread influenza activity as of Jan. 25 -- the majority of which is being attributed to the influenza A(H1N1)pdm09 (pH1N1) virus that sparked the 2009 flu pandemic -- family physicians likely will want to be on the lookout for severe respiratory illness that disproportionately affects young and middle-aged adults. The likelihood is particularly great among pregnant women and other at-risk individuals.

According to the CDC(www.cdc.gov), the highest hospitalization rates are being seen among adults 65 and older (41 per 100,000), followed by those ages 50-64 (32 per 100,000) and children younger than age 5 years (30 per 100,000). Even so, of the 5,494 laboratory-confirmed influenza-associated hospitalizations reported to the agency as of the week of Jan. 19-25, 60 percent have been in adults ages 18-64.

Story highlights
  • Thirty-eight states were reporting widespread influenza activity as of Jan. 25, the majority of which is being attributed to the influenza A(H1N1)pdm09 virus that sparked the 2009 flu pandemic.
  • Pregnant women are at increased risk for complications from the flu -- particularly this strain -- and yet barely half of these women (usually less) are immunized each year, says the CDC.
  • The AAFP has joined the agency and multiple other groups in signing on to a letter urging health care professionals to ensure pregnant women receive the vaccine.

In contrast to typical flu seasons in which the burden of disease falls overwhelmingly on those younger than age 5 and those 65 and older, this same pattern of increased hospitalizations among people in this median age range also was seen during the 2009 H1N1 pandemic.

Even back in December, a CDC Health Advisory(emergency.cdc.gov) warned of the particular disease pattern already being seen this season. "Early observations from the 2013-14 influenza season indicate that some persons infected with pH1N1 virus have had severe illness," says the advisory. "While most of these people with severe illness have had risk factors for influenza-associated complications, including pregnancy and morbid obesity, several have not."

This level of disease severity is particularly troubling in light of a recently released analysis(healthyamericans.org) from the Trust for America's Health that reports only 35.7 percent of adults ages 18-64 received the influenza vaccine during the 2012-13 flu season. Overall, fewer than half of Americans (45 percent) got a flu shot during the 2012-13 season despite a clear recommendation that all people ages 6 months and older be immunized unless a specific contraindication is present. Still, that percentage was higher than the 41.8 percent who received the vaccine during the 2011-12 season.

The upshot: The majority of adults in this 18-64 age range, including those at increased risk for complications from influenza such as pregnant women, remain wholly or inadequately protected from infection caused by the pH1N1 virus.

Staff-driven Vaccine Protocol Fails to Boost Rates

The CDC's Advisory Committee on Immunization Practices, along with the AAFP and the American College of Obstetricians and Gynecologists, began recommending the inactivated influenza vaccine for pregnant women(www.expert-reviews.com) in 2004. Yet despite that continuing recommendation, barely half of these women (usually less) receive the vaccine each year, says the CDC.

Research has shown that pregnant women whose physician or other health care professional recommends immunization are far more likely to be vaccinated than those who do not, but barriers to vaccine administration -- including physician time constraints -- persist. In an attempt to boost immunization rates, many facilities have initiated interventions such as standing orders or other protocols.

A study in the January-February issue of the Journal of the American Board of Family Medicine(www.jabfm.org) examines one such effort, comparing immunization offering and provision rates among pregnant women when staff-driven versus physician-driven protocols were used.

Data were drawn from chart reviews conducted at four sites during the 2010-11 and 2011-12 flu seasons. Patient records at three clinics in large academic medical centers (i.e., a family medicine residency clinic, an OB/Gyn residency clinic and a private clinic staffed by faculty OB/Gyns) and one community-based OB/Gyn practice were examined.

A staff-driven protocol, in which the vaccine was offered and provided by a licensed vocational nurse or medical assistant, was used at the academic faculty site the first year of review and at that site along with the family medicine residency clinic during the second year of review. In all other instances, a physician-driven protocol was used.

Overall, with the staff-driven protocol, the average offering rate was 99.7 percent, and, of those who were offered the vaccine, 38.2 percent of patients received it, for a total effective vaccination rate of 38.1 percent. With the physician-driven protocol, 54.5 percent of patients were offered the vaccine, and 70.7 percent of them received it, yielding an effective total vaccination rate of 38.5 percent.

From these findings, say the authors, it appears that "a simple protocol change to staff alone offering vaccine is unlikely to improve rates of maternal influenza vaccination." Additional studies evaluating other interventions are needed, they note.

In response, the AAFP has joined the CDC and other groups in signing on to a "Dear Colleague" letter that calls for clinicians to ramp up efforts to immunize their pregnant and postpartum patients against the flu. The letter restates, in large part, advice presented in an HHS letter the Academy and other groups signed on to in December 2011.

Noting that infection with the pH1N1 virus that is the predominant circulating strain this season "was especially hard on pregnant women" in 2009, the current letter points out that the "CDC has received reports of flu hospitalizations and deaths in pregnant women with influenza virus infection this season."

"Influenza activity in the U.S. remains high overall and may continue for weeks," says the letter. "It is important that we be vigilant in protecting pregnant and postpartum women from flu."

The first and most important step in preventing the flu is, of course, immunizing patients against the virus. To that end, the groups lay out a number of key points clinicians can discuss with their pregnant patients during that vaccination conversation. Among them are the following:

  • Various physical changes that occur naturally during pregnancy, such as those affecting the immune system, heart and lungs, heighten the risk of severe flu-related illness in pregnant women.
  • Pregnant women who contract influenza are at increased risk for premature labor and delivery.
  • Immunization during pregnancy confers protection from flu-related illness and hospitalization for both mother and infant (up to 6 months of age). Given that infants cannot be immunized until they are 6 months old, maternal immunization provides their sole defense against the infection until they reach that age.
  • Millions of pregnant women have received influenza vaccine for decades, with no resulting harms seen in these women or their infants.
  • Pregnant women should receive an injection of inactivated influenza vaccine, not the live attenuated vaccine that is given as a nasal spray, and the shot may be administered during any trimester.
  • Postpartum women, including those who are breastfeeding, may receive either form of the vaccine.

Two specific antiviral drugs, the neuraminidase inhibitors oseltamivir (Tamiflu) and zanamivir (Relenza), are recommended to treat patients -- including pregnant women -- who contract the flu during the 2013-14 season. (High levels of resistance to the adamantanes persist among 2009 H1N1 and influenza A (H3N2) viruses, and these drugs are not effective against influenza B viruses at all.) Oseltamivir and zanamivir have been shown to lessen symptoms and shorten the time patients are ill by one or two days. They also can prevent serious flu complications, such as pneumonia.

During the 2009 H1N1 pandemic, in fact, prompt antiviral treatment of hospitalized pregnant women who had the flu was shown to reduce rates of respiratory failure and death, says the letter. Although starting antiviral treatment within two days of illness onset is optimal, the drugs still can be helpful even if initiated after that point.

As always, physicians and other health care professionals can find influenza information and resources(www.cdc.gov) ranging from flu activity and surveillance maps to downloadable patient education materials at the CDC website.