• Respiratory diseases US approves the use of Pfizer's vaccine against RSV respiratory virus

Human metapneumovirus (HMPV), discovered in 2001 in the Netherlands, is an RNA virus that belongs to the family of paramyxoviruses, viruses that are known to cause a wide range of common infections.

Research reveals that this pathogen, which causes severe and unexplained respiratory infections in children, is closely related to avian metapneumovirus, which infects birds. Therefore, the new virus is called human metapneumovirus. Scientists believe it likely jumped from birds to humans and circulated for at least half a century before being discovered.

Other known paramyxoviruses include parainfluenza, respiratory syncytial virus (RSV), measles, and mumps. In most people, this virus only causes a simple cold. HMPV is the second most common cause of respiratory infections in children after RSV.

Why is the virus on the rise?

As with other respiratory illnesses, cases of human metapneumovirus are on the rise, according to the Centers for Disease Control and Prevention, which has recorded unusual spikes in the United States. As of mid-March in the US, nearly 11% of samples tested tested positive for HMPV, 36% higher than the average seasonal peak in the pre-pandemic period.

Experts hypothesize that the rise of a number of viruses, including RSV, may be a consequence of excessive mask use that has prevented the immune system from coming into contact with the usual viruses and better managing future exposures.

After so much time of social distancing, children have fewer immune defenses capable of repelling multiple viruses at the same time. Children are usually infected with metapneumovirus by age 5.

What are the symptoms of HPV?

The virus, which usually appears in winter and spring, most often affects the upper respiratory tract and causes nasal congestion, cough and shortness of breath, wheezing and shortness of breath, as well as fever. The infection usually lasts three to seven days.

When does it become dangerous?

Human metapneumovirus is usually mild, but can have more serious consequences for young children, the elderly, and people with weakened immune systems. In some cases, it can progress to the lower airways and lead to a more serious illness, such as bronchiolitis, which causes swelling, irritation, and mucus buildup in the lungs, or pneumonia. Depending on the severity, the virus usually lasts the same amount of time as other viruses, between three and seven days.

How is it transmitted?

Human metapneumovirus is transmitted similarly to other viruses: through airborne particles produced by coughing or sneezing, through physical contact with a person who has the virus, or by handling contaminated objects and then touching your eyes, mouth, or nose.

The virus can spread even when people are asymptomatic, just like Sars-CoV-2. According to one study, asymptomatic human metapneumovirus infections account for at least 38% of infections.

How widespread is it?

A 2020 study in Lancet Global Health estimated that there were more than 14 million HMPV infections among children younger than 5 years in 2018, more than 600,000 hospitalizations, and more than 16,000 deaths. The infection results in weak or incomplete immune protection, and humans are reinfected for life.

Is there a vaccine?

There is no vaccine for human metapneumovirus and treatment is limited to supportive care to facilitate breathing. In the rare, more severe cases, patients are admitted to intensive care even though most people recover on their own.

  • United States
  • Respiratory diseases

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