Human metapneumovirus (HMPV) has been in the news since January this year following an outbreak in China, raising global concerns about its fatality and whether it might be a variant of COVID-19. The virus has gained considerable attention after being recognised worldwide as a respiratory illness. In this blog, you will learn about the key differences and similarities between HMPV and COVID-19.

Origins and Discovery of HMPV vs COVID-19

HMPV has existed across the globe for nearly 60 years, but it was first discovered in 2001 by Bernadette G. van den Hoogen and her team in the Netherlands. They identified the virus while investigating unexplained respiratory illnesses in children. HMPV belongs to the Pneumoviridae family and is closely related to the respiratory syncytial virus (RSV).

COVID-19, on the other hand, was first identified in 2019 in Wuhan, China, and rapidly spread worldwide, leading to a global pandemic in 2020. The World Health Organization (WHO) announced a pandemic in March 2020. Initially referred to as the 2019 novel coronavirus because it had not previously infected humans, it later showed increased transmissibility. The causative virus is SARS-CoV-2, or Severe Acute Respiratory Syndrome Coronavirus 2, a member of the coronavirus family that includes several human and animal pathogens.

Key Similarities Between HMPV and COVID-19

Symptoms: Both HMPV and COVID-19 primarily affect the respiratory tract and can cause upper and lower respiratory infections. The mild symptoms of HMPV often resemble those of the common cold or flu. However, HMPV symptoms in severe cases may overlap with those seen in COVID-19, including respiratory distress and complications such as pneumonia and bronchiolitis.

In infants and children, HMPV symptoms may present with persistent high fever, coughing, nasal congestion, wheezing, breathlessness, and difficulty feeding or hydrating. Among adults, symptoms are typically flu-like and include mild to high fever, nasal congestion, sore throat, body aches, fatigue, and occasional shortness of breath. Hospitalisation may be required if a person experiences significant breathlessness, which could indicate pneumonia or other serious pulmonary conditions.

COVID-19 symptoms are less common in HMPV, such as sudden loss of taste or smell, muscle aches, sore eyes, numbness or tingling in the limbs, insomnia, and gastrointestinal disturbances like diarrhoea and nausea. In severe cases, patients may experience difficulty breathing at rest, inability to speak full sentences, confusion, drowsiness, chest tightness or pain, cold or clammy skin, bluish discolouration, and loss of consciousness, all of which warrant immediate medical attention.

Common symptoms shown by both viruses include fever, cough, shortness of breath, fatigue, and nasal congestion or runny nose.

High-Risk Groups: Vulnerable groups for both viruses include pregnant women, young children, the elderly, and those with weakened immune systems. HMPV is particularly prevalent among children under five and is a major cause of respiratory illness in older adults and immunocompromised individuals. While HMPV can cause hospitalisation in some severe cases, its mortality rate is comparatively low.

COVID-19, in contrast, poses a serious threat across all age groups, especially in individuals with comorbidities such as diabetes, cardiovascular disease, and respiratory disorders. In some cases, it has caused long-term health complications referred to as 'long COVID', a group of symptoms that persist for weeks, months, or even years after the initial COVID-19 infection.

Modes of Transmission: Both HMPV and COVID-19 are airborne respiratory viruses that spread through droplets released when an infected person talks, coughs, or sneezes. Transmission of this respiratory infection is more likely in close-contact settings or poorly ventilated indoor environments. Both viruses can survive on surfaces for a period of time, increasing the risk of infection through surface contact followed by touching the face.

Primary Organ System Affected: The primary target for both viruses is the respiratory system. Both can cause inflammation of the airways, nasal congestion, coughing, and breathing difficulties. In severe cases, both HMPV and COVID-19 can lead to pneumonia or other forms of acute respiratory distress.

Key Differences Between HMPV and COVID-19

Seasonal Patterns:HMPV infections typically occur in winter and spring. In contrast, COVID-19 can occur at any time, without following a specific pattern or trend.

Speed of Spread and Incubation: COVID-19 spreads more rapidly and extensively than HMPV. Symptoms of HMPV usually appear within three to six days of exposure and resolve within two to five days. COVID-19 symptoms generally appear around the fifth or sixth day after exposure and can persist for up to two weeks or longer.

Diagnosis: Both viruses are diagnosed using reverse-transcriptase polymerase chain reaction (RT-PCR) tests, which detect viral RNA from respiratory specimens. RT-PCR for HMPV is highly sensitive and can distinguish it from similar viruses like RSV or influenza.

COVID-19 diagnosis also uses RT-PCR but is often supported by rapid antigen testing for faster results. Chest imaging, such as X-rays or CT scans, may be used in severe cases to assess lung damage, although these tools cannot definitively distinguish between HMPV and COVID-19.

Treatment: HMPV treatment currently has no specific antiviral therapies available. Management primarily focuses on supportive care, including rest, hydration, and over-the-counter medications to reduce fever and nasal congestion. Hospitalisation and oxygen therapy required in severe cases.

Treatment options for COVID-19 have evolved crucially after the onset of the pandemic. In moderate to severe cases, antiviral drugs such as remdesivir, monoclonal antibody therapies, and corticosteroids like dexamethasone are now used for the treatment. Supportive care, including oxygen and mechanical ventilation, is essential for those patients who are in respiratory distress.

Importantly, COVID-19 vaccines are widely available and have played a crucial role in reducing disease severity and hospitalisation. No vaccine currently exists for HMPV.

Health Effects: COVID-19 can affect multiple organ systems and interfere with various bodily functions, while HMPV primarily impacts the lungs and airways.

Fatality: COVID-19 has a higher fatality rate due to its involvement of multi-organ systems and potential for severe complications. While HMPV is generally less fatal, it can be life-threatening for vulnerable groups such as infants, the elderly, and those with compromised immune systems. Early detection and treatment are critical for both.

Prevention of HMPV and COVID-19

Preventive strategies for both viruses are largely similar and rooted in good hygiene practices. These include regular handwashing with soap and water, especially after touching surfaces or returning from public places. Using a hand sanitizer with at least 60 percent alcohol is advised, as it comes in handy when you are outside or when soap and other cleaning agents are unavailable.This is particularly important to prevent unintentional transfer of the virus from surfaces to the face.

Wearing masks in crowded or enclosed indoor spaces with poor ventilation, avoiding close contact with sick individuals, and frequently disinfecting high-touch surfaces are also recommended.

Final Takeaway

Whether it is COVID-19 or HMPV, both diseases can often be prevented by adhering to basic hygiene and protective measures. However, if infection does occur despite precautions, there is no need to panic. Early detection and timely medical care can effectively manage symptoms and prevent serious complications such as pneumonia.