Virus on the Rise in California – Here’s Everything You Need to Know about the COVID ‘Runner-up!’

Virus on the Rise in California – Here’s Everything You Need to Know about the COVID ‘Runner-up!’

This past winter delivered a triple threat that included the extremely contagious SARS-CoV-2 variant, influenza, and the respiratory syncytial virus, (RSV,) after many waves of COVID-19 throughout the pandemic.

A less common respiratory virus, however, has been on the rise more lately and has symptoms that are strikingly similar to those of RSV.

If you weren’t formally tested for it in a hospital, there is a significant possibility you had it at some point but didn’t know it.

The prevalence of the human metapneumovirus, or HMPV, increased across the nation in the late winter and early spring, according to the CDC.

Infectious disease expert John Swartzberg says “During the first two years of the COVID pandemic, infections were much less common, as with other respiratory viruses like influenza and RSV. But this year — again like RSV and influenza — we have seen spikes in cases with human metapneumovirus.”

As per California Department of Public Health statistics, the proportion of HMPV tests that were positive started increasing gradually back in October, peaked at around 15 percent in mid-March, and then started to fall by mid-May.

With that being said, here’s the information from Bay Area specialists about HMPV, how it differs from other disorders, and why it isn’t more well understood.

In 2001, human metapneumovirus, a respiratory virus belonging to the same family as RSV, was identified in samples from children in the Netherlands who had respiratory infections.

Swartzberg said that “Immunologic studies suggest it has been around and causing disease worldwide for at least 60 years.”

The HMPV virus spreads by big droplets, just like other respiratory viruses.

When an infected individual coughs or sneezes, it can be spread by inhaling the droplets they release, especially if you’re close to them.

“It can also be transmitted if these droplets get on an inanimate object and someone else touches it, and touches their nose, mouth, or eyes afterward. It can also transmit hand to hand,” Swartzberg shared.

According to infectious disease expert Peter Chin-Hon, it is particularly transmissible in household settings.

“Most people get infected before age 5, then re-infections occur during life. School-aged kids likely bring it into the household and infants and others get infected in this way.”

According to Swartzberg, HMPV can cause lower respiratory tract infections like pneumonia and bronchitis after an incubation period of 5-9 days.

It can also lead to upper respiratory tract infections like the common cold during that same time.

The latter may necessitate hospitalization and is more frequent in youngsters under the age of five or in elderly people.

Swartzberg mentioned that oftentimes, infections tend to be asymptomatic which means that “If you do become ill, most people have typical cold symptoms, sometimes with a cough or wheezing, and are much better within a week. It can exacerbate wheezing in people with asthma.”

HMPV has a low profile mostly because, until recently, we have not routinely tested for it, especially in outpatient settings and in urgent care, according to doctors.

That is because there’s no vaccination to prevent it or medication to cure it, and the diagnosis usually doesn’t alter the treatment plan.

Multiplex PCR is a panel test that some hospitals employ to check for a variety of common respiratory infections, including HMPV.

This is normally only carried out if a patient is immunocompromised or presents with severe symptoms, such as pneumonia.

HMPV was referred to by Chin-Hong as the “runner-up” to COVID-19, influenza, as well as RSV.

“There is more attention paid to it as we have more molecular techniques — like PCR — that can find it. Prior to this, it was nearly impossible to identify outside of the research setting.”

Just like RSV, HMPV cases becoming more common follow a period of decline during the beginning of the pandemic.

Chin-Hong said that “This likely reflects loss of population immunity during the last three years, and people coming back in close proximity to each other. Because we don’t normally test for HMPV in the community, we mainly see it in the inpatient setting in the sickest patients. It’s likely much more common than we think.”

According to clinical assistant professor of infectious diseases Jake Scott, the virus usually spreads in late winter and early spring and can also linger in the summer at lower levels.

In order to stop the spread of HMPV and other common respiratory infections, he advised practicing “basic, meticulous hand hygiene.”

Scott advised patients to avoid long-term care institutions and hospitals if they were ill because outbreaks do occur there, especially in children’s hospitals.

According to Scott, it’s crucial to maintain current vaccinations for people, such as the pneumococcal vaccine for seniors.


Katherine is just getting her start as a journalist. She attended a technical school while still in high school where she learned a variety of skills, from photography to nutrition. Her enthusiasm for both natural and human sciences is real so she particularly enjoys covering topics on medicine and the environment.

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