Francisco R. Velázquez: What happens when three respiratory viruses coincide?

By Francisco R. Velázquez, M.D., S.M., FCAP

Recently we have heard terms such as “tripledemic” and “immunity debt” being used to describe the convergence and the consequences of three pathogens sharing time and geography. Two of these, namely respiratory syncytial virus (RSV) and influenza, have somewhat overlapping seasonal patterns. The third, COVID-19, has not demonstrated the same seasonality.

COVID-19’s most recent variant, omicron, has been around for a year, since the first case was identified in the United States. Obviously, omicron, like its predecessors, has mutated numerous times and now there are hundreds of sub-lineages. Although only some have generated a significant number of cases. In addition, different than past variants, new sub-lineages have not demonstrated exclusive dominance. This accounts for the slower transition from one to the next and the lengthy presence globally – more than what we’ve seen with any other variant.

Which brings us to the present. It has been over two years since RSV and the flu followed the usual infection pattern of years past. Mainly, COVID-19 dominated the conversation as the most common respiratory virus for the past two years. Case data for respiratory illnesses other than COVID-19 showed transmission in children and adults was significantly lower in 2020 and 2021. These were the times when the strictest precautions were in place, limiting the number of potential human hosts available for viruses to replicate and spread. Most of the non-pharmaceutical interventions – such as social distancing, masking, isolation and quarantine – did limit the ability of respiratory viruses to spread.

COVID-19, flu and RSV are all respiratory viruses, but there are some differences in transmission patterns. COVID-19 spreads more effectively through respiratory droplets and aerosols generated when coughing, sneezing, and talking. The flu also spreads effectively through droplets and aerosols and by contact with contaminated surfaces. RSV, in addition to the respiratory contagion, is very effective at transmission from contaminated surfaces (counters, cribs, doorknobs, toys) where it can survive for hours and on your hands for almost a half hour. It can also spread through direct contact such as when kissing a child’s face good night. With that in mind, hand washing and disinfecting frequently touched surfaces is useful for many infectious agents and critical in preventing RSV transmission.

Over the past few months, we all have seen and heard the news from across the country about the high number of cases and hospitalizations attributable to all three viruses. Initially, RSV and the flu were the culprits. Then after the Thanksgiving holiday, an increase in COVID-19 was also documented – perhaps not as high as previous years, but still causing more than 2,000 deaths a week in the U.S. In some ways this is not unexpected as the many precautions around COVID-19 were removed, gatherings and travel increased, and many other activities resumed a more normal pattern. The delay afforded by those measures decreased thus allowing for the viruses to spread again. The flu has already caused 13 million illnesses and at least 7,300 deaths. The impact of RSV has been felt in pediatric institutions where inpatient bed use has been as high as 100% in some areas. The combination of RSV, flu and other cold type viruses has caused double-digit percentages of absenteeism in schools around the country. Over the past few weeks, hospitalizations for adults have also increased, further aggravating the labor shortage that health care has been experiencing over the past three years.

With the holiday season upon us, the questions many are asking are what does this mean and what can I do? These are great questions as there are a lot of ways in which each one of us can contribute to preventing the spread and protecting those at the highest risk for severe disease.

First and foremost, assess your risk and the risk for those around you, particularly the very young and the very old, those with pre-existing conditions, and anyone who is immunosuppressed because of a clinical condition or therapeutic interventions.

Plan holiday activities to minimize risk, using the outdoors whenever possible. Places like Riverfront Park, the skate ribbon, sleigh rides and sledding hills are great options for outdoor activities. Maximize ventilation if indoors. Clean and sanitize frequently used surfaces, practice frequent hand-washing, avoid touching your face as much as possible, and practice respiratory etiquette. Absorbent disposable paper tissues are great for covering your mouth and nose when sneezing and blowing your nose. Don’t forget to wash your hands afterward. Wear a mask when appropriate based on your risk, the place and activity and the risk to others, particularly if you may have been exposed to a virus.

For the flu and COVID-19, we have vaccines and boosters; consult your provider as to your eligibility. There are laboratory tests for all three viruses your provider can order if needed, and for COVID-19, there are a lot of over-the-counter options.

One of the most powerful tools in communicable disease prevention is to avoid exposures; if you are sick, stay home.

If we all do our part, this will be the most festive holiday season in at least three years.

Francisco R. Velázquez, M.D., S.M., FCAP, is health officer for the Spokane Regional Health District.