Reports of a surge in respiratory virus cases in China have evoked dark echoes of the start of the Covid-19 pandemic almost exactly five years ago.
But despite the superficial similarities, medical experts say this situation is very different and much less worrisome.
The Chinese cases are believed to be infections with human metapneumovirus, known to doctors as HMPV. Here’s what we know so far:
What is HMPV?
It is one of several pathogens that circulate around the world every year, causing respiratory diseases. HMPV is common, so common that most people become infected as children and may get several infections over the course of their lives. In countries with cold months HMPV may have an annual season, much like influenza, while in places closer to the Equator it circulates at lower levels throughout the year.
HMPV is similar to a virus better known in the United States: respiratory syncytial virus, or RSV. It causes symptoms very similar to those associated with the flu and Covid, including cough, fever, nasal congestion and wheezing.
Most HMPV infections are mild and resemble attacks of the common cold. But more severe cases can cause bronchitis or pneumonia, particularly among infants, the elderly and immunocompromised people. Patients with pre-existing lung conditions, such as asthma, chronic obstructive pulmonary disease, or emphysema, are at greater risk of serious outcomes.
In higher-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 for at least 60 years. While it’s nothing new, it doesn’t have the name flu, Covid or even RSV, said Dr. Leigh Howard, an associate professor of pediatric infectious diseases at Vanderbilt University Medical Center.
One reason is that it is rarely spoken of 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 unrecognized and are attributed to whatever respiratory problem is going on.”
How does a person get infected with HMPV?
The virus spreads primarily through droplets or aerosols from coughs or sneezes, through direct contact with an infected individual, or through exposure to contaminated surfaces, essentially the same way people get colds, flu, and Covid.
Is there a vaccine? Or a treatment?
There is no vaccine against HMPV. But there is a vaccine for RSV, and research is underway to find a vaccine that can protect against both viruses with just one vaccine, since they are similar. There is no specific antiviral treatment for HMPV; Treatment focuses on managing symptoms.
What does China say about this?
Chinese authorities have acknowledged that HMPV cases are increasing, but have stressed that the virus is a known entity and is not a serious concern. The coronavirus that causes Covid-19 was a new pathogen, so people’s immune systems had not developed defenses 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 HMPV cases are increasing among children aged under 14 years. The increase was particularly notable in northern China, he said. Flu cases have also increased, he said.
Cases could rise 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 extent and intensity of the spread of respiratory infectious diseases this year will be lower than last year.”
Official Chinese data shows that HMPV cases have been increasing since mid-December, both in outpatient and emergency settings, according to Xinhua, the state news agency. Some parents and social media users were unfamiliar with the virus and were seeking advice online, the outlet said; he urged calm and ordinary precautions such as washing hands often and avoiding crowded places.
At a routine press conference on Friday, a Foreign Office spokesperson reiterated that cases of influenza and other respiratory viruses routinely increase at this time of year but that they “appear to be less severe and spread on a smaller scale than in the previous year.” previous”. .”
Chinese officials last week said they would set up a monitoring system for pneumonia of unknown origin. It will include procedures for laboratories to report cases and for disease control and prevention agencies to test and manage them, state broadcaster CCTV reported.
What has been the public response in China?
Online, amid comments from people who say they have never heard of HMPV and express concern that it is a new pathogen, state media has sought to reassure people, warning them against blindly taking antiviral drugs.
Some users joked that they would finally be able to use the masks they had stockpiled during the coronavirus pandemic. Many commenters discussed a general increase in illnesses, not just HMPV: “Why is the flu so bad” was trending Monday on Weibo, a social media platform.
What does the World Health Organization say?
The WHO expressed no concern. Dr. Margaret Harris, a spokeswoman for the organization, cited weekly reports from Chinese authorities showing a predictable increase in cases.
“As expected for this time of year, winter in the Northern Hemisphere, there is a month-over-month increase in acute respiratory infections, including seasonal influenza, RSV and human metapneumovirus,” he said via e -mail.
On Tuesday, the organization released a statement saying: “WHO is in contact with Chinese health officials and has not received any reports of unusual patterns of outbreaks.” He added: “Chinese authorities report that the health system is not overwhelmed and no emergency declarations or responses have been triggered.”
Should I worry?
The reports from China are reminiscent of those in the confusing early days of the Covid pandemic, and the WHO is still urging China to share more information about the origins of that outbreak, five years later.
But the current situation is different in fundamental respects. Covid was a virus that spread to humans from animals and was previously unknown. HMPV is well studied and there is ample capacity to test for it. There is broad population-level immunity to this virus globally; there wasn’t any, due to Covid. A severe HMPV season can strain hospital capacity, particularly pediatric departments, but does not overwhelm medical centers.
“However, it is also critical that China shares its data on this epidemic 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 who gets infected. Additionally, we will need genomic data that confirms that HMPV is the culprit and that there are no significant mutations of concern.”
Viviana Wang contributed reporting from Beijing.