U.S. COVID-19, influenza 'twindemic' fears valid but glimmer of hope in global reports

Surging coronavirus cases stoke fears of a “dark winter” ahead with seasonal influenza looming large in the United States, but international health reports spotlight how pandemic precautions may—or may not—allay a coming “twindemic.”

Published Oct. 26 in the British Medical Journal, an article describing influenza cases and respiratory diseases throughout the Southern Hemisphere’s winter months, June-August 2020, settled upon an encouraging assessment: Australia, New Zealand, South Africa and several South American countries “skipped” influenza season altogether. Considered a bellwether for strain circulation and severity in the Northern Hemisphere, the lower hemisphere’s cold season tipped American public health officials to a particularly devastating 2017 influenza season, as well as a 2019 season that spiked much earlier and with greater potency than normal.

Such is the case, public health officials remain cautious toward 2020 even as those same countries have registered some of the lowest influenza rates in over a decade, prompting at least one academic to claim a “near extinction of influenza.”

Per the report, New Zealand registered a 99.8% reduction in influenza cases with only a miniscule 0.8% peak in self-reported influenza-like symptoms, while Australia confirmed only 33 positive cases among 60,000 tests; Chile confirmed 12 positives among nearly 21,200 tests; and South Africa, only 6 positives among nearly 2,100 tests. But sheer lack of cases is an incomplete picture.

As opposed to evidence of a less virulent or weaker influenza strain in circulation, these data likely reflect adherence to ongoing measures to stop the spread of SARS-CoV-2, the virus causing the COVID-19 pandemic. For instance, New Zealand garnered global attention for a relatively hardline approach to COVID-19 elimination that saw a nationally mandated, seven-week stay-home order combined with travel restrictions and social-distancing regulations. Thus far, the small island nation’s COVID-19 rates have stayed in the 332 cases per million population range. Similarly, Australia’s own lockdowns and regulations kept COVID-19 spread to 1,082 cases per million, as compared to much larger nations, such as the United Kingdom’s 14,902 cases per million, France’s 20,304 cases per million or the United States’ 27,045 cases per million.

But governments’ COVID-19 orders aside, the minimal influenza spread may also be attributed to individual steps people are taking to mitigate their own COVID-19 risk, e.g., greater attention to hand hygiene, cleaning and adherence to social distancing. Those three steps alone may have increased efficacy against an influenza virus that has a much lower R₀ value than SARS-CoV-2.

“Data from this article strongly emphasizes what a tremendous value can be placed upon performing simple measures during the U.S. cold and flu season,” says Hilary Hawthorne, O.D., AOA Ethics & Values Committee member. “Continued use of a few small steps that have helped mitigate a risk of COVID-19’s pandemic will be effective in the coming months. As primary eye care providers continue to practice good hand hygiene, disinfection and spatial distancing, it serves as a means to continually educating our patients, staff, families and general public in the months ahead.”

While the relatively quiet influenza season thus far is likely chalked up to a combination of all of the above, there’s one more factor that American public health officials also are counting on to mitigate fears of a twindemic: increased influenza vaccinations.

The influenza vaccine

This season, a record 18 million influenza vaccines were made available in Australia alone—nearly five million more than in 2019 and 10 million more than 2017—while, reportedly, two-thirds of the population received a vaccine. Composed of a similar formulation to last season, the 2020-21 vaccine contains an attenuated H1N1, H3N2 and a pair of B-viruses, and appears to have been a good match.

Australian data show of the 306 influenza viruses characterized this season, 91.5% were influenza A and 8% were of influenza B/Victoria lineage. Importantly, 65% of H3N2 isolates were antigenically similar to the corresponding vaccine components and 44% of H1N1 were, as well. All influenza B isolates were antigenically similar.

So, what does that mean for the United States?

On Oct. 1, the Centers for Disease Control and Prevention (CDC) and National Foundation for Infectious Diseases launched a public health campaign to urge influenza vaccine uptake for all people ages 6 months or older with no contraindications. Citing a 52% vaccination coverage in 2019-20, the CDC estimates the vaccine averted an estimated 7.5 million influenza illnesses, 105,000 influenza hospitalizations and 6,400 influenza deaths. Still, the CDC emphasizes that’s only half of Americans—and therein lies concerns for a twindemic.

“While it is unclear how the pandemic will affect the flu season, CDC is preparing for COVID-19 and seasonal flu to spread at the same time,” the health agency notes. “Co-circulation could place a tremendous burden on our health care system and result in many illnesses, hospitalizations and deaths. Getting a flu vaccine is something easy people can do to protect themselves and their loved ones, and to help reduce the spread of flu this fall and winter.”

These next several weeks are critical for Americans’ vaccinations, the CDC says, as it can take up to two weeks for the body to develop sufficient antibodies to stave off an active virus. While influenza-like illness reporting currently shows low or minimal activity nationwide, influenza cases tend to start climbing toward the end of December and into the new year.

What’s more, public health officials stress that even if an influenza vaccine isn’t as effective as Australian data suggest, the vaccine can still ease illness severity in people who do get sick. That’s especially crucial during the current COVID-19 emergency as hospital ICU census is reportedly increasing in communities nationwide.

“As primary eye care providers, our responsibility is and has always been to provide the most competent eye care, safely and efficiently to our patients,” says Sandra Fortenberry, O.D., AOA Ethics & Values Committee member. “In our current pandemic, it has become even more important to emphasize to our staff and patients the importance of hygiene and following CDC guidelines. Utilizing flu vaccinations will dampen the rise in stress on the overall health care system and ultimately benefit doctors, staff, patients and our loved ones.”

Protect your practice

Consequently, it’s helpful for optometric practices and clinics to remind their doctors and staff about the importance of influenza vaccinations, as well as redoubled adherence to infection control protocols in light of the COVID-19 pandemic. The CDC’s Advisory Committee on Immunization Practices and the Healthcare Infection Control Practices Advisory Committee recommend that all U.S. health care workers get vaccinated annually against influenza, and 2019-20 data indicates over 80% of health care personnel did so.

The hope is that as COVID-19 is top-of-mind for patient care personnel, and a vaccine for the pandemic virus could soon be within grasp, it won’t take much convincing for physicians and staff to receive an influenza vaccine, too. However, when it comes to the American public, the data isn’t so reassuring—only about half of U.S. adults say they would get a COVID-19 vaccine.

Doug Totten, O.D., AOA Ethics & Values Committee chair, emphasizes the Standards of Professional Conduct when reflecting on current twindemic concerns: “Optometrists have an ethical obligation primarily to their patients but also to society in general.” Modeling and reinforcing these public health recommendations will be key this influenza season.

“Not only do doctors of optometry have an obligation to protect their patients and staff from the so-called potential ‘twindemic,’ but also they have an obligation to be examples for appropriate behavior to their communities and with those they influence. This could be the case even when doctors might question what response is indicated related to benefits and risks,” Dr. Totten says.

“It may always be better to err on the side of caution.”

Interested in reading more about ethical dilemmas affecting the practice of optometry? Access the AOA’s EyeLearn Professional Development Hub to find ethics case studies and recommendations from the AOA’s Ethics & Values Committee.

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