New virus? Highly lethal? Don’t be fooled! Three things you must know about “human metapneumovirus”

[This issue's rumors]:

“It’s not COVID-19 or H1N1, but the mortality rate after 100 days of infection is 43%!”

Image from the Internet

"The respiratory virus surveillance system of the Centers for Disease Control and Prevention (CDC) shows that since this spring, human metapneumovirus (hMPV) has been prevalent in various regions of the United States. The virus is wreaking havoc in intensive care units and pediatric hospitals in major hospitals in the United States."

Image from the US Centers for Disease Control and Prevention

Recently, many people may have seen these two pieces of news on their mobile phones. At the same time, topics such as #Chinese metapneumovirus infection# and #human metapneumovirus# also topped the hot search list. So, is human metapneumovirus really a new virus? Is the "lethality" of human metapneumovirus really that great?

【NetEase Health Assessment】：

The headline party attracts attention, and the data concept is replaced

【Key points for identifying rumors】

Point 1: It is not a new virus. It was discovered and named more than 20 years ago.

As early as 22 years ago, a virus team in the Netherlands published a paper stating that they had isolated a virus with clinical symptoms similar to human respiratory syncytial virus infection and named it human metapneumovirus (hMPV) [1]. The article mentioned that according to serological studies, almost all Dutch children had been exposed to human metapneumovirus before the age of 5, and the virus has been circulating in humans for at least 50 years. So there is no need to be misled by some headlines and panic that human metapneumovirus is a new virus.

Point 2: The concept has been replaced, the mortality rate is not 43%!

The data circulating online that "the mortality rate is 43% 100 days after infection" is a misinterpretation of the concept. In fact, the data comes from a study published in the United States in 2013. The subjects of this study were patients who had received hematopoietic stem cell transplants. This group had low immunity and a very high rate of severe illness after infection with human metapneumovirus. The 100-day mortality rate was as high as 43%[2].

Human metapneumovirus infection is not uncommon in the population. A survey report on human metapneumovirus serum antibody levels in the Beijing population published in the Chinese Journal of Pediatrics in 2005[3] clearly stated that 13.9% of six-month-old infants in the survey sample had been infected with human metapneumovirus, and as many as 38.5% of people over 50 years old had been infected with human metapneumovirus. So there is no need to panic, because you and I may have been infected before.

The clinical manifestations of human metapneumovirus infection are usually mild, and may include respiratory symptoms such as cough, fever, and nasal congestion. These symptoms cannot be distinguished from other common respiratory viruses such as influenza virus[4], so it is difficult for us to determine whether we are infected with human metapneumovirus. At this time, PCR testing of respiratory specimens (such as nasopharyngeal swabs, oropharyngeal swabs, etc.) can be performed to determine whether we are infected with human metapneumovirus.

We would like to remind everyone that although the mortality rate of human metapneumovirus infection is not as high as 43% as reported online, and most people experience mild symptoms, young children, the elderly, and people with weakened immune systems still need to be especially careful. Once infected, these people are likely to develop severe lower respiratory tract diseases, which may progress to bronchitis or pneumonia, and in severe cases, may be life-threatening[5].

Point 3: There is no specific medicine or vaccine, so daily protection is needed to reduce infection

At present, there is no specific antiviral therapy for human metapneumovirus, nor is there a vaccine to prevent human metapneumovirus. Current treatment is still mainly to relieve symptoms. If the symptoms are mild, symptomatic treatment can be given at home. Once respiratory symptoms such as difficulty breathing and high fever worsen, go to the hospital immediately for treatment.

How can we prevent human metapneumovirus infection?

According to the website of the Centers for Disease Control and Prevention (CDC) in the United States [6], human metapneumovirus is transmitted through person-to-person contact, and the most likely route of transmission is contact with secretions from coughing or sneezing, touching objects contaminated with the virus and then touching the eyes, mouth, or nose. Daily prevention methods for human metapneumovirus are similar to those for other respiratory viruses:

Wash your hands frequently with soap and running water.

Avoid touching your eyes, nose, or mouth with unwashed hands.

Avoid close contact with people who are sick.

But if you already have cold-like symptoms you should pay attention to:

Cover your coughs and sneezes.

Wash your hands promptly and properly (with soap and running water for at least 20 seconds).

Avoid sharing cups and utensils with others.

Pay attention to self-isolation.

References:
[1] van den Hoogen BG, de Jong JC, Groen J, Kuiken T, de Groot R, Fouchier RA, Osterhaus AD. A newly discovered human pneumovirus isolated from young children with respiratory tract disease. Nat Med. 2001 Jun;7(6):719-24.
[2] Renaud C, Xie H, Seo S, Kuypers J, Cent A, Corey L, Leisenring W, Boeckh M, Englund JA. Mortality rates of human metapneumovirus and respiratory syncytial virus lower respiratory tract infections in hematopoietic cell transplantation recipients. Biol Blood Marrow Transplant. 2013 Aug;19(8):1220-6. doi: 10.1016/j.bbmt.2013.05.005. Epub 2013 May 13. PMID: 23680472; PMCID: PMC3752411.
[3] Zhao Linqing, Cao Shouchun, Zhu Runan, et al. A preliminary investigation of serum antibody levels against human metapneumovirus in the Beijing population[J]. Chinese Journal of Pediatrics, 2005, 43(12):4.
[4] Human Metapneumovirus: Common yet Underdiagnosed
https://www.medscape.com/viewarticle/867267?src=par_cdc_stm_mscpedt&faf=1
[5] Boivin G, Abed Y, Pelletier G, Ruel L, Moisan D, Cote S, Peret TC, Erdman DD, Anderson LJ. Virological features and clinical manifestations associated with human metapneumovirus: a new paramyxovirus responsible for acute respiratory-tract infections in all age groups. Journal of Infectious Diseases. 2002;186:1330–1334.
[6] Human Metapneumovirus (HMPV)
https://www.cdc.gov/ncird/human-metapneumovirus.html