Many Northern Hemisphere countries have an increase in acute respiratory infections during this time of year. These increases are usually driven by seasonal epidemics of respiratory infections, including seasonal influenza, respiratory syncytial virus (RSV), and other common respiratory viruses like human metapneumovirus (hMPV) and mycoplasma pneumonia. Many countries carry out regular surveillance for acute respiratory illnesses and common respiratory pathogens.
In several temperate Northern Hemisphere nations, rates of influenza-like illness (ILI) and/or acute respiratory infection (ARI) have recently increased and are now above baseline values, consistent with seasonal trends. Many Northern Hemisphere countries see increased seasonal influenza activity. Where surveillance data is available, trends in RSV detections now differ by area, with declines documented in most regions except in North America.
Recently, there has been increased interest in hMPV cases in China, with reports of hospitals being inundated. hMPV is a common respiratory virus that circulates in many countries from winter to spring, although not all nations test for and report data on hMPV trends. While some cases may require hospitalization for bronchitis or pneumonia, the majority of people infected with hMPV experience moderate upper respiratory symptoms comparable to the common cold and recover within a few days.
According to data issued by China for the period ending December 29, 2024, acute respiratory illnesses have grown in recent weeks, as have detections of seasonal influenza, rhinovirus, RSV, and hMPV, notably in China's northern regions. The observed rise in respiratory pathogen detections is typical for this time of year throughout the Northern Hemisphere winter.
In China, influenza is the most commonly discovered respiratory virus causing acute respiratory illnesses. The WHO is in communication with Chinese health officials and has received no information on unusual outbreak trends. As per the Chinese authorities, the healthcare system is not overburdened, and no emergency declarations or reactions have been triggered. WHO continues to monitor respiratory infections at the global, regional, and country levels using collaborative surveillance systems, providing updates as appropriate.
Public Health Response
Based on the projected increase in respiratory infections during the winter season, countries, including China, have been sending health messages to the public about how to avoid the spread of respiratory infections and minimize illness burden.
WHO Risk Assessment
In temperate regions, seasonal outbreaks of common respiratory diseases, including influenza, are frequent throughout the winter months. The recent spike in acute respiratory illnesses and accompanying pathogen detections in many Northern Hemisphere nations is to be expected and not unexpected for this time of year. The co-circulation of respiratory infections may impose a strain on healthcare institutions.
WHO advice
WHO recommends that people living in winter-prone locations take standard precautions to avoid the spread of respiratory infections and decrease the dangers they represent, particularly to the most vulnerable. People with mild symptoms should stay at home to prevent infecting others and relax.
People who are at high risk, or who have complicated or severe symptoms, should consult a doctor right away. Individuals should also consider wearing a mask in busy or poorly ventilated areas, covering coughs and sneezing with a tissue or bent elbow, washing their hands often, and receiving required immunizations as advised by their physician and local public health officials.
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