This winter, it’s common to hear people complain that they cannot shake their lingering runny or coughing nose after a respiratory infection. Other symptoms may have gone away. They may feel better for a few days, but then the symptoms come back a week later.
The doctors say this is not unusual, but it may be more apparent this year.
Influenza and respiratory syncytial viruses (RSV) all circulate widely. By December 16, the number of flu-related hospitalizations was nearly 200% higher than it had been in the four previous weeks. The latest available data shows that Covid hospitalizations grew by around 40% in the four weeks ending December 9.
NBC News interviewed seven doctors from seven different states to find out why symptoms in some people can last for weeks or even months. They suggested several possible explanations.
Experts said that many people this winter are more susceptible to respiratory illness because they have not had a recent infection. Some people may have had back-to-back conditions that they mistook for lingering symptoms.
After the pandemic, when common viruses were not widely spread, some people may have forgotten how long respiratory illnesses can last.
Dr. Linda Bell is the state epidemiologist for South Carolina.
The ‘Immunity Debt’ is catching people up.
Some people may not have had as much exposure to RSV or flu as they otherwise would have. This is because masking and isolation were used during the pandemic. This can lead to an “immunity deficit” – a decreased immunity that makes people more susceptible.
“As we encounter more viruses we haven’t encountered in the past, we might feel that some of them are more severe, and we may have more severe symptoms,” said Dr. Molly Fleece. She is a hospital epidemiologist with the University of Alabama Birmingham Medicine.
Doctors said that a lack of vaccination-induced protection could also make people more susceptible to severe illnesses and make it difficult to recover.
Last week, the Centers for Disease Control and Prevention (CDC) sent an alert to healthcare providers warning about low vaccine rates for Covid and flu.
RSV vaccines are approved for pregnant women and older adults, but only 17% of people 60 years and older have received an RSV vaccination as of December 9. In October, the CDC announced a shortage of a newly-approved RSV antibody injection. Additional doses were made available last month, and 230,000 are expected to be delivered in January.
This year, the flu vaccination rate for adults is 42 percent, and for children, it’s 43 percent, compared to 47 and 57, respectively, in last season. Only 18% of adults and 8% of eligible children have received the latest Covid vaccine.
Doctors said that masking and social distancing were also more common last year.
“That could be the reason people are sicker now,” said Dr. Caroline Goldzweig. She is chief medical officer at Cedars-Sinai Medical Foundation, Los Angeles.
Two infections in a row
Doctors said that this may be the first year in which COVID-19, influenza, and RSV are all circulating at once. This could mean there is a greater chance of getting sick than in previous winters.
Dr. Larissa Pisney, infectious disease specialist at UCHealth, Aurora, Colorado, said, “In the last few years, Covid and RSV were the predominant respiratory viruses. Now, multiple respiratory virus are rising simultaneously.”
This could increase the risk of re-infection.
It’s possible to have multiple respiratory infections over the winter, according to Dr. Daniel Ouellette. He is a pulmonary specialist at Henry Ford Health.
According to Dr. Mandy Cohen, the director of the CDC, it’s possible to have more than one virus in your system at once.
Cohen stated that “we see co-infections about at the same level as this time last year.”
Doctors have reported an increase in bacterial illnesses such as whooping cough, strep throat, or pneumonia that follow or happen at the same time as a viral infection.
“In certain situations, having viral respiratory illnesses increases your risk of bacterial pneumonia. We’ve seen this for a very long time, and we saw it with Covid too,” said Dr. Shivanjali Shankaran. She is an infectious disease specialist at Rush University Medical Group in Chicago.
Normal for symptoms to persist or recur
According to Dr. Donald Yealy of the University of Pittsburgh’s Medical Center, symptoms that disappear and then reappear may be caused by the same virus infection.
He said: “You may have an initial infection and start to recover, but then you can experience recrudescence – in other words, recurrence symptoms while you are recovering.” “People might mistake this for two separate infections.”
Doctors said that it’s not uncommon to be sick for a few weeks. Covid, influenza, and RSV are all possible causes of a postviral cough.
This postviral cough does not mean that the person can still spread the virus to others. Fleece explained that it was a residual of the prior infection.
A small minority may take months or even years to recover. According to a survey conducted by the Census Bureau in June, around 6 percent of U.S. adults suffer from Long Covid. It’s also possible to experience lingering symptoms from colds or flu.
A report published last week revealed that flu could cause a persistent cough or shortness of breath for at least 18 months. In October, an analysis of U.K. adults found that cold viruses could cause symptoms such as diarrhea, stomach pain, or coughing for up to a month following an initial infection. Scientists still don’t know why.