Throughout 2020, there was a marked decrease in the amount of influenza cases globally (World Health Organization, 2020: 1). This is largely due to the implementation of the COVID-19 restrictions such as mask- wearing, social distancing, and reduced travel. Coming into a post-vaccine phase of the pandemic, these public health measures have been drawn back in many countries. As the northern hemisphere heads into its flu season, some public health officials have become concerned about the possibility of a twindemic. This term refers to an intense flu season coinciding with the ongoing COVID-19 pandemic.
Influenza refers to a series of respiratory viruses which can be broken down into types A, B, and C (Glezen, 2013: e43). Type C is generally seen as a much milder strain of the virus with less clinical relevance compared to type A and B (Glezen, 2013: e43). The type A lineages have zoonotic hosts in a series of bird and pig species. This is in comparison to the type B lineages which largely stay within human populations. This past year, global influenza surveillance has been reduced due to the demands of COVID-19 on the public health sector (Larrauri 2021:1). This has led to the possibility that this year’s flu vaccines may not be made up of the most prevalent strains of both type A and B. The World Health Organization advised that global vaccination efforts for this flu season should be around the following strains:
A Strains:
- A/Victoria/2570/2019 (H1N1) pdm09-like virus
- A/Cambodia/e0826360/2020 (H3N2)-like virus
- A/Wisconsin/02/2019 (B Victoria lineage)-like virus
B Strains:
- B/Washington/02/2019 (B/Victoria lineage)-like virus
- B/Phuket/3073/2013 (B/Yamagata lineage)-like virus
Similar to influenza, coronaviruses are a type of zoonotic respiratory virus. The coronavirus family divides into Alpha and Beta type classifications. The SARS-CoV-2 of the current pandemic is a Beta coronavirus (Morens et al., 2020: 956). The virus is believed to have originated in bats. It moved into human populations through either direct transmission from a bat or through indirect transmission via the Malaysian pangolin (Morens et al., 2020: 957).
But what exactly would a twindemic look like? This would largely be seen as more strain placed on the already beaten down health care systems of the northern hemisphere. A specific challenge that worries public health officials is the possibility of co-infection of COVID-19 and the influenza virus. Currently, there is limited information on the possible clinical implications of this type of co-infection (Chotpitayasunondh et al., 2020: 408). This could make it incredibly difficult to plan treatments to address the needs of co-infected patients. Additionally, the twindemic could make it harder for health care providers to allocate the proper resources to patients as a diagnosis between the two viruses can be difficult due to similar symptom presentations. Notably, these are fever, fatigue, and dry cough (Chotpitayasunondh et al., 2020: 409).
The possibility of a twindemic will not fall evenly across social, economic, and racial divides. Historically disenfranchised populations will most likely see the brunt of this health crisis. For example, African Americans are more likely to be affected by both COVID-19 and influenza (Ferdinand et al., 2020: 683). This is due to large amounts of vaccine hesitancy and lack of trust in health care providers stemming from historical manipulation and abuse of these communities by health care professionals. Additionally, these communities are more likely to have underlying comorbidities from their social determinants of health. These refer to factors in daily life that affect the ability for an individual to exhibit a healthy lifestyle such as access to fresh food, educational opportunities, and access to employment (Ferdinand et al., 2020: 684). These communities tend to have more negative social determinants of health which stem from a history of underlying discriminatory policies that impair access to these factors.
The prevention of this twindemic is possible. Through the general public getting the available COVID-19 vaccinations and their yearly flu shot, the mass spread of both of these viruses can be halted. Additionally, viral spread can be limited through the continued utilization of masks and social distancing. These types of preventative measures can help reduce stress on already burnt out medical professionals and their limited resources. As well as protect more vulnerable individuals and communities from incurring serious medical consequences from either or both of these viruses.
References:
Chotpitayasunondh, T., Fischer, T. K., Heraud, J. M., Hurt, A. C., Monto, A. S., Osterhaus, A., Shu, Y., & Tam, J. S. (2020). Influenza and COVID‐19: What does co‐existence mean? Influenza and Other Respiratory Viruses, 15(3), 407–412.
Ferdinand, K. C., Nedunchezhian, S., & Reddy, T. K. (2020). The COVID-19 and Influenza "Twindemic": Barriers to Influenza Vaccination and Potential Acceptance of SARS-CoV2 Vaccination in African Americans. National Medical Association, 112(6), 681–687.
Glezen, W. P., Schmier, J. K., Kuehn, C. M., Ryan, K. J., & Oxford, J. (2013). The Burden of Influenza B: A Structured Literature Review. American Journal of Public Health, 103(3), e41-e51.
Larrauri, A., & Trilar, K. P. (2021). Preparing for an influenza season 2021/22 with a likely co-circulation of influenza virus and SARS-CoV-2. Eurosurveillance, 26(41), 1-4.
Morens, D. M., Breman, J. G., Calisher, C. H., Doherty, P. C., Hahn, B. H., Keausch, G. T., Kramer, L. D., Leduc, J.W., Monath, T.P., & Taubenberger, J. K. (2020). The Origin of COVID-19 and Why It Matters. American Journal of Tropical Medicine and Health, 103(3), 955–959.
World Health Organization. (2021). Coadministration of Seasonal Inactivated Influenza and COVID-19 Vaccines, 1–5.
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