Reports of a surge in cases of the respiratory virus in China have evoked dark echoes of the start of the Covid-19 pandemic almost exactly five years ago.
But despite the apparent similarities, the situation is very different and much less worrying, according to medical experts.
The Chinese cases are believed to be infections with the human metapneumovirus, known to doctors as HMPV. Here’s what we know so far:
What is HMPV?
It is one of many pathogens that circulate around the world each year and cause respiratory illnesses. HMPV is common – so common that most people will be infected while they are still children and may experience multiple infections over the course of their lives. In countries where it is cold for months, HMPV may have an annual season, much like the flu, while in places closer to the equator it circulates at lower levels throughout the year. year.
HMPV is similar to a virus better known in the United States – respiratory syncytial virus, or RSV. It causes symptoms similar to those associated with the flu and Covid, including cough, fever, nasal congestion and wheezing.
Most HMPV infections are mild and resemble bouts of the common cold. But severe cases can lead to bronchitis or pneumonia, especially in infants, the elderly and immunocompromised people. Patients with pre-existing lung diseases, such as asthma, chronic obstructive pulmonary disease, or emphysema, are at higher risk of serious outcomes.
In high-income countries, the virus is rarely fatal; in low-income countries with weak health systems and poor surveillance, deaths are more common.
How long has this virus been around?
The virus was identified in 2001, but researchers say it has been circulating in humans since at least 60 years old. Although it’s not new, it doesn’t have the name flu, Covid or even RSV, said Dr. Leigh Howard, associate professor of pediatric infectious diseases at Vanderbilt University Medical Center.
One reason is that it is rarely discussed by name, except when people are hospitalized with a confirmed case.
“The clinical features are really difficult to distinguish from other viral diseases, and we don’t routinely test for HMPV like we do for Covid, influenza or RSV,” Dr. Howard said. “So most infections go unnoticed and are attributed to whatever respiratory problem is circulating. »
How does a person become infected with HMPV?
The virus is spread primarily through droplets or aerosols from coughing or sneezing, direct contact with an infected person, or exposure to contaminated surfaces – essentially the same way people get colds, flu, and Covid.
Is there a vaccine? Or treatment?
There is no vaccine against HMPV. But there is a vaccine against RSV, and research is underway to find a vaccine that could protect against both viruses in one shot, since they are similar. There is no antiviral treatment specifically for HMPV; Treatment focuses on symptom management.
What does China say about it?
Chinese authorities have acknowledged that HMPV cases are increasing, but stressed that the virus is a known entity and is not a major concern. The coronavirus that causes Covid-19 was a new pathogen, so people’s immune systems had not developed a defense against it.
At a press conference held by the Chinese Center for Disease Control and Prevention on December 27, Kan Biao, director of the center’s Institute of Infectious Diseases, said that cases of HMPV were increasing among children 14 years and younger. The increase was particularly notable in northern China, he said. Flu cases have also increased, he said.
Cases could increase during the Lunar New Year holiday in late January, when many people travel and gather in large groups, he said.
But overall, Kan said, “judging from the current situation, the scale and intensity of the spread of infectious respiratory diseases this year will be lower than last year.”
Official Chinese data show that cases of HMPV have increased since mid-December, both in outpatient and emergency settings. according to Xinhuathe national news agency. Some parents and social media users were unaware of the virus and sought advice online, the outlet said; he urged taking calm and ordinary precautions, such as washing hands frequently and avoiding crowded places.
In a routine press briefing Fridaya Foreign Office spokesperson reiterated that cases of flu and other respiratory viruses increase regularly at this time of year but that they “appear to be less serious and spread on a smaller scale compared to to the previous year.
Chinese officials said last week that it set up a surveillance system for pneumonia of unknown origin. It will include procedures for laboratories to report cases and for disease control and prevention agencies to verify and treat them, state broadcaster CCTV reported.
What was the public reaction in China?
Online, faced with comments from people saying they had never heard of HMPV and expressing concern that it was a new pathogen, state media sought to reassure the population, warning them against blindly taking antiviral drugs.
Some users joked that they could finally use the masks they had stockpiled during the coronavirus pandemic. Many commenters spoke of a general increase in illness, not just HMPV: “Why does the flu hurt so much? was trending on Weibo, a social media platform, on Monday.
What does the World Health Organization say?
The WHO has not expressed concern. Dr. Margaret Harris, a spokesperson for the organization, cited weekly reports from Chinese authorities showing a predictable increase in cases.
“As expected for this time of year, the Northern Hemisphere winter, there is a month-over-month increase in acute respiratory infections, including seasonal influenza, RSV and human metapneumovirus,” she said via email.
On Tuesday, the organization released a statement saying: “WHO is in contact with Chinese health authorities and has not received any reports of unusual outbreak patterns.” It adds: “Chinese authorities report that the health system is not overwhelmed and that no emergency declaration or response has been triggered.”
Should I be worried?
The reports from China are reminiscent of those from the confusing early days of the Covid pandemic, and the WHO is still urging China to share more information about the origin of that outbreak, five years later.
But the current situation is different in essential respects. Covid was a virus that spread to humans from animals and was previously unknown. HMPV is well studied and there is extensive screening capacity. There is broad population-level immunity to this virus worldwide; there was none, for Covid. A severe HMPV season can strain hospital capacity – particularly pediatric wards – but does not overwhelm medical centers.
“However, it is also vital that China shares its data on this outbreak in a timely manner,” said Dr Sanjaya Senanayake, an infectious disease specialist and associate professor of medicine at the Australian National University. “This includes epidemiological data on infected people. Additionally, we will need genomic data confirming that HMPV is the culprit and that there are no significant mutations of concern.
Viviane Wang contributed reporting from Beijing.
