H3N2 Flu Strain Mismatch Could Hit Elderly Patients Hard
A bad season in the ‘land down under’ could spell U.S. trouble
November 1st, 2017
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By Gary Evans, Medical Writer
An H3N2 influenza A strain that has drifted via mutation from its match in the current U.S. vaccine could spell a mean flu season, particularly for elderly patients and nursing home residents.
“People 65 and over account for about 85% of the flu-related deaths that occur in this country,” said Kathleen Neuzil, MD, MPH, FIDSA, director at the Center for Vaccine Development at the University of Maryland School of Medicine. “They also account for the majority of the hospitalizations that occur. The good news last year was that those trends [of vaccination of the elderly] appeared to be stabilizing. And what we’d like to see this year is a real increase. Even if we’re at a 65% level, that still means a third of people 65 and over still aren’t getting influenza vaccine.”
Neuzil joined other public health officials recently in Washington, DC, at an influenza press conference at the National Foundation for Infectious Diseases (NFID).
Public health officials are urging vaccination of the elderly and long-term care staff, who are all too often the most under-immunized healthcare workers. During the 2015-2016 flu season, for example, only 68% of healthcare workers in long-term care were vaccinated, compared to 76% in ambulatory care and 92% in hospitals, the CDC reports.1
While more and more hospitals are mandating flu vaccination as a condition of employment, the CDC reports that only 26% of survey respondents who worked in long-term care reported that their employer required them to be vaccinated.
“I very vividly remember a patient that I took care of who was brought in from an extended care facility with a severe influenza pneumonia,” Neuzil said. “She had been there for months, so she wasn’t out circulating in the community, exposing herself to influenza at the grocery store. We brought influenza to her. So, either the healthcare workers in that facility brought her influenza, or her family member or friends brought her that influenza.”
There is particularly concern for this frail population — who typically have difficulty mounting a strong immune response even if vaccinated — because Australian public health officials recently reported that the circulating H3N2 strain is causing severe infections in the elderly. The concern is that the summer season in Australia and the Southern Hemisphere is often predictive of what flu strains the U.S. and the Northern Hemisphere will face. Health officials in Australia administered the same vaccine now being rolled out in the U.S.
Australian officials issued a September 27 statement warning that “2017 has been characterized by high levels of influenza A (H3N2) which disproportionately affects the elderly. We have seen reports of high numbers of deaths in nursing homes this year and also amongst healthy adults. These are tragic events which underscore the message that influenza is a serious disease and that vaccination is absolutely critical for protecting individuals and the community. We do know that the 2017 vaccines have had a relatively good match with circulating strains, which provides the best opportunity for protection. There is, however, evidence that the effectiveness of the vaccines has been less than usual this year, particularly in terms of protecting the elderly against influenza A (H3N2).”2
One factor in Australia is that, apparently, some vaccines specifically designed for the elderly — including a high-dose shot and an adjuvant formula — were not cleared for use in the country this season. However, Nuezil said there is at least one high-dose vaccine available for the elderly in the U.S.
“It’s the same content of the influenza vaccine that everybody else receives, but it’s four times the dose, four times the antigen,” she said. “And it has been shown to improve the immune response in people over 65, and prevent more illness and hospitalizations in people over 65. Similarly, [we have] the adjuvant vaccine — it’s an additional ingredient that boosts the immune response.”
Those weapons should certainly be brought to bear, but the degree of drift in the circulating H3N2 strain could still spell trouble if it amounts to a clear mismatch. An H3N2 flu virus which eluded the vaccine strain caused a particularly bad flu season in the U.S. in the 2014-2015 season.
It also is unknown how widely the H3N2 strain will circulate in the U.S., but the H3N2 strain in the current vaccine should provide some protection, public health officials emphasized at the press conference.
“The proteins on the outside of that H3N2 virus are still quite similar to what’s in the current vaccine,” says William Schaffner, MD, medical director of the NFID and a professor of preventive medicine at Vanderbilt University School of Medicine. “So, we ought to be well-prepared. This H3N2 strain is the one that usually causes more illness, more complications in older adults. So, if you needed another reason to be vaccinated, there it is. Best [to] get that protection.”
Flu is nothing if not unpredictable, he adds. “As they say, if you’ve seen one flu season, you have seen one flu season,” Schaffner says.
The World Health Organization has recommended that the next flu vaccine for the Southern Hemisphere replace the H3N2 vaccine component with an H3N2 A/Singapore/INFIMH-16-0019/2016-like virus.
The vaccine that will be used in the U.S. and the other Northern Hemisphere countries will still have the H3N2 A/Hong Kong/4801/2014-like virus. The other strains in the trivalent flu vaccine are A/Michigan/45/2015 (H1N1) and B/Brisbane/60/2008-like virus. Quadrivalent influenza vaccines will contain these three viruses and an additional influenza B vaccine virus, a B/Phuket/3073/2013-like virus, according to the CDC.3
“Clearly, it was a severe season in Australia this summer,” says Dan Jernigan, MD, a medical epidemiologist at the CDC, who somewhat downplayed the threat. “Does that mean we’ll have a bad season this fall? We don’t know exactly, but we want to be prepared for that, and that’s one reason why it’s important to get your vaccine. There’s been a little bit of drift, some change, but there’s not been a significant mutation in the H3N2.”
No Mist Vaccine Again
A lack of efficacy has again sidelined the mist vaccine nasal spray, which was popular with children but was not recommended last year, and is not being recommended by the CDC for the 2017-2018 season. However, children remain a risk group for severe flu and should be targeted for the current flu season, much like the elderly.
“Unfortunately, flu is very severe and I have to remind everyone that children do die of influenza,” said Patsy Stinchfield, RN, senior director of infection prevention and control at Children’s Health Network in Minneapolis. “In the U.S. alone, last year, 105 children died of influenza — and this is well below the number of average deaths per year. Even back in the 2009-2010 season, we saw as many as 358 children die of influenza.”
In addition to pediatric deaths, CDC estimates that since 2010, flu-related hospitalizations among children younger than five years of age have ranged from 7,000 to 26,000 every year, she says.
“Working in a children’s hospital, as I have for 30 years, we take care of the sickest of the sick, and I can tell you I have seen way too many children in the ICU on ventilators who have died than I ever care to remember,” Stinchfield said. “It’s a very sad situation for everybody — those who care for them, and their families.”
Severe influenza complications are most common in children younger than two years of age, but bad outcomes can occur in kids of any age, she says.
“It can be in all ages, in children with underlying chronic diseases such as asthma or neurological problems where they’ll have difficulty with their secretions, but also in healthy children with no chronic diseases,” she says.
Recent research shows influenza vaccine reduces the risk of flu-associated deaths by 51% in children who have underlying chronic conditions, and by 65% in healthy children, Stinchfield says.4
“The risk of severe outcomes among children is high, but I’m pleased to see that 76% of children in the U.S. age six to 23 months old were vaccinated last season, exceeding the national public health goal of 70% vaccine coverage as outlined in the Healthy People 2020 goals,” she adds. “That is great. However, this is the only age group of children — and, in fact, the only age group overall that met the goal. With influenza vaccination, the coverage decreases as children get older.”
In another key recommendation for children, the CDC advises that a child who has never received a flu vaccine and is between the ages of six months through eight years should receive two shots one month apart, she notes.
“That’s a nuance just for young children — first-time vaccinated,” Stinchfield says. “If you were vaccinated in the year prior, you’ll only need one this year. Finally, protection should start even before babies are born. Vaccinations of moms-to-be during any trimester is important to protect both them and developing babies against influenza.”
Pregnant women may receive any licensed, recommended, age-appropriate influenza vaccine, the CDC recommends.
Last season about 53% of pregnant women reported vaccination before or during pregnancy, Schaffner adds.
“That’s a great measure of progress, but you can see roughly half of pregnant women during the influenza season still did not get vaccinated,” he says. “We all have to do more work there.”
As infection preventionists are well aware, the best way to protect vulnerable patients in the hospitals and other settings is to achieve a high vaccination rate in the staff delivering care.
“Vaccination coverage continues to be higher among healthcare personnel working in hospitals,” Schaffner said. “These large institutions are really getting it done. They’re getting all of their personnel vaccinated. However, the rates are still lower among healthcare personnel working in ambulatory and long-term care facilities. We as healthcare professionals still have work to do there.”
A recent CDC internet survey revealed that 79% of healthcare workers overall were immunized during the 2016-2017 flu season, continuing a trend that has seen vaccinations level off over the last few years. “As in previous seasons, coverage was highest among healthcare personnel (HCP) who were required by their employer to be vaccinated (97%) and lowest among HCP working in settings where vaccination was not required, promoted, or offered on-site (46%),” the CDC reported.1
Indeed, the CDC cites studies in the literature that show that immunizing healthcare workers against flu protects patients.5,6
“It’s a patient safety issue,” Schaffner said. “We don’t want to give flu to the patients for whom we are providing care.”
The plateau effect seen in worker immunizations was mirrored by a similar stall in efforts to promote flu vaccine. “While we don’t know for sure why vaccination coverage among healthcare workers has plateaued over the past four influenza seasons, we do know that workplace efforts to promote vaccination — which are associated with [higher] vaccination coverage — have also plateaued,” said Carla Black, MD, the lead author of the CDC paper. “By the 2016-17 season, almost all healthcare workers working in hospital settings reported either being required to be vaccinated or being offered flu vaccine at their workplace free of charge. However, healthcare settings other than hospitals have not followed suit in increasing their efforts to promote vaccination in the workplace.”
The CDC’s Healthy People 2020 goal is to achieve 90% flu vaccination coverage among healthcare workers. Specific occupational groups must be targeted if this goal is to be met.
“Fewer than 70% of assistants and aides were vaccinated, while coverage was over 90% for physicians, PAs, nurses, nurse practitioners, and pharmacists,” said Black, who was interviewed separately and was not at the NFID press conference.
When employers had on-site vaccination clinics for more than one day, four out of five healthcare personnel took advantage of the opportunity to get vaccinated, even in the absence of a requirement, she added. “We know that comprehensive work-site intervention strategies that include education, promotion, and easy access to vaccination at no cost for multiple days can increase healthcare worker vaccination coverage,” she said.
There also are lingering issues with healthcare workers declining flu shots due to myths and misconceptions about vaccine safety.
“Approximately 30% of unvaccinated respondents in this year’s survey reported that fear of side effects or some other safety concern was the main reason that they were not vaccinated,” Black says. “Flu vaccines are among the safest medical products in use. Hundreds of millions of Americans have safely received flu vaccines over the past 50 years, and there has been extensive research supporting the safety of flu vaccines.”
This has been a long-standing issue in healthcare, and an anti-vaccination movement in the public has also cited religious beliefs and safety concerns in refusing vaccination for children. A Michigan woman was recently arrested for refusing to allow her nine-year-old son to receive vaccines, something the child’s father insisted on as part of an ongoing custody battle.7
- CDC. Black CL, Yue X, Ball SW, et al. Influenza Vaccination Coverage Among Health Care Personnel — United States, 2016–17 Influenza Season. MMWR 2017;66:1009–1015.
- Australian Department of Health. Statement from the Chief Medical Officer on seasonal influenza vaccines. September 27, 2017: http://bit.ly/2xMVxr5.
- CDC. Grohskopf LA, Sokolow LZ, Broder KR, et al. Vaccines: Recommendations of the Advisory Committee on Immunization Practices — United States, 2017–18 Influenza Season. MMWR 2017;66(2):1–20.
- Flannery B, Reynolds SB, Blanton L, et al. Influenza Vaccine Effectiveness Against Pediatric Deaths: 2010-2014. Pediatrics 2017;139(5): Epub: http://bit.ly/2wG2VmA.
- Ahmed F, Lindley M, Allred N, et al. Effect of Influenza Vaccination of Health Care Personnel on Morbidity and Mortality Among Patients: Systematic Review and Grading of Evidence. Clin Infect Dis 2014;58:(1):50-57.
- Griffin MR. Influenza Vaccination of Health Care Workers: Making the Grade for Action. Clin Infect Dis 2014;58:(1):58-60.
- Phillips K. A mother refused to follow a court order to vaccinate her son. Now she’s going to jail. Washington Post. Oct. 4, 2017: http://wapo.st/2y8tsMs.
Elderly and long-term care staff are all too often the most under-immunized healthcare workers.
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