Infectious Disease Experts Warn of Multiple Viruses This Fall and Winter Season 

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As flu shots start to become available next week, top infectious disease experts at UCHealth warn of another concerning virus season this fall and winter with flu, COVID-19, and respiratory syncytial virus (RSV) expected to be circulating at the same time. Coloradans are encouraged to get vaccinated against the flu as soon as possible as the state and country expect another early start to the season.  

 Flu season typically peaks in December going into the holiday season, and lasts until about April. This year, Coloradans can expect to see flu start circulating in October and possibly peaking in November. Predictions for this year’s respiratory virus season are based on modeling and trends seen in the southern hemisphere. In Australia, the combination of viruses was of serious concern; cases of all three viruses increased at the same time, reaching higher-than-average levels.  

“It was a rough couple of months seeing all three of those viruses at the same time, and children seem to have been affected by the flu and RSV combination more this year in Australia than in previous years,” said Dr. Michelle Barron, senior medical director of infection prevention and control at UCHealth. “This is why we’re encouraging everyone, and especially kids, parents and grandparents, to get their vaccinations early.” 

New COVID-19 Vaccine to Become Available  

As Colorado and UCHealth start to see COVID-19 cases and hospitalizations rise slightly due to waning immunity and a new strain, a new monovalent COVID-19 vaccine is set to become available by the end of September. This new vaccine focuses on the XBB.1.5 Omicron variant. In addition to the flu shot, Coloradans are encouraged to get this vaccine as soon as it becomes available — especially those who are over the age of 65, individuals with underlying health conditions, and those who are immunocompromised.  

“The new COVID-19 vaccine has been changed to target a more current version of the virus in the community. This is similar to what is done for flu shots every year. There are no new safety issues or concerns with this new vaccine,” said Dr. Barron.  

Although it is safe to get the flu vaccine and the new COVID-19 vaccine together, Coloradans are encouraged to get each as soon as they become available — which could mean getting the flu shot first, and then the COVID-19 shot a few weeks later.   

COVID-19 symptoms can look similar to that of the flu—headache, runny nose, body aches, fever, cough, and a sore throat. If someone is symptomatic, it is important to still get tested to determine what virus you have and what treatment options are best. For COVID, medications like Paxlovid and Remdesivir are still available and have been proven to be effective in lowering the risk of severe infection. Monoclonal antibodies are no longer considered effective in the treatment for COVID-19. 

Protect Yourself Against RSV  

In addition to the flu vaccine and new monovalent COVID-19 vaccine, the FDA recently approved a new vaccine to protect older adults and immunocompromised individuals against respiratory syncytial virus or RSV. This vaccine is specifically for those who are 60 or older and pregnant people. 

“RSV is known to cause ‘croup’ in kids. In adults, it can cause bronchitis and pneumonia in individuals who are older or have underlying lung disease like asthma or COPD, or have compromised immune systems due to medications or underlying conditions,” Dr. Barron said. 

As UCHealth infectious disease experts prepare to see the combination of viruses this fall and winter season, Coloradans are encouraged to stay home if they are sick, practice proper hand hygiene, use sanitizer, and wash surfaces thoroughly. Anyone who has a weakened immune system should wear a mask in large gatherings. 

“We know that vaccines work, and we have repeatedly seen this in recent years. Even if a vaccine doesn’t completely prevent you from getting sick, it will reduce the severity of the illness and reduce the chance that you could end up in the hospital,” said Dr. Barron. “Staying healthy should be a priority for everyone, and getting a flu vaccine, COVID-19 vaccine, and an RSV vaccine (if you are eligible) is a great way to meet that goal.” 

To learn more about influenza prevention and care, visit

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