Hantavirus vs. COVID: The differences in symtoms, spread and treatment — and why we're not facing another pandemic

Three people have died and five other cases have been reported following a hantavirus outbreak linked to the MV Hondius cruise ship.

The situation has drawn comparisons to the quarantined Diamond Princess cruise ship during the early days of COVID-19, but experts stress that hantavirus is very different from COVID and, notably, not a newly discovered virus.

Here’s how the two compare, and why hantavirus is not going to become the next pandemic.

Though some of the symptoms are similar, hantavirus and COVID behave very differently, and it’s these differences that make the current outbreak extremely unlikely to become a pandemic.

Dr. Bryce Warner, research scientist at the Vaccine and Infectious Disease Organization and professor at the University of Saskatchewan, told National Post: “Hantavirus is also contracted through inhalation, like Coronaviruses, but it replicates much more slowly. It really takes unique circumstances for hantavirus to spread from person to person, like very prolonged close contact with someone who is showing those signs and symptoms and is quite ill.”

He added that the longer incubation period and difference in disease progression means hantavirus doesn’t spread readily from person to person.

Meanwhile, Dr. Isaac Bogoch, professor at the University of Toronto and an infectious diseases specialist, highlighted that experts have existing knowledge and experience with hantavirus, whereas COVID-19 was a new strain.

He told National Post: “We’ve known about hantaviruses for decades, including the Andes strain. For about three decades, there have been outbreaks with this virus before that were quelled with appropriate public health measures.”

Dr. Bogoch pointed to a 2018 outbreak in Argentina , where the virus is endemic in some areas, which saw 34 confirmed infections and 11 deaths.

“We have to be humble. Let’s not pretend we know everything about the virus. But in the same breath, it’s not like we’re starting from scratch. We have three decades of experience,” he said.

Dr. Bogoch also praised Canada’s ability to deal with the outbreak: “We have the capacity at our national microbiology lab to make a diagnosis of a hantavirus infection. We have the clinical capacity, if someone is ill, to care for people in a setting where the person will get top-notch medical care, and we can prevent transmission in a hospital environment. We also have the public health capacity to do further contact tracing in the country.”

Three Canadians linked to the infected cruise are currently isolating in Ontario and Quebec. An additional three who may have had contact with a confirmed case on a recent flight have been asked to isolate, health officials confirmed on Friday.

Four more Canadians remain on the MV Hondius, due to dock in the Canary Islands on Sunday.

Early symptoms of hantavirus resemble the flu. According to the U.S. Centers for Disease Control and Prevention (CDC), these include fever, fatigue and muscle aches, and roughly half of patients experience headaches, dizziness, chills and nausea.

Later symptoms can include coughing and shortness of breath. In severe cases, symptoms can progress to respiratory distress as fluid builds up in the lungs. Patients may require intensive care, including oxygen support or mechanical ventilation.

Symptoms of hantavirus typically appear one to eight weeks after exposure.

COVID-19 has a much wider range of symptoms, some of which are similar to hantavirus. These include: fever or chills, cough, shortness of breath, sore throat, congestion or runny nose, loss of taste or smell, fatigue, muscle or body aches, headache, nausea or vomiting and diarrhea.

But the CDC notes that COVID symptoms vary widely and are dependent on variants and vaccination status.

Extreme symptoms include difficulty breathing and chest pain. Patients in the worst cases during the pandemic were treated in ICU with intubation and a ventilator, which forces oxygen into the lungs.

Symptoms of COVID may appear between two and 14 days after infection, according to the CDC, but some may experience no symptoms at all.

Hantavirus is spread to humans through contact with infected rodents or their urine, droppings and saliva.

Human-to-human transmission is extremely rare, but the Andes hantavirus strain, which is the strain identified on the Hondius, has been shown to spread between people.

Where this happens, it is through prolonged close contact. The shared, confined spaces on the ship are thought to have facilitated the spread in this latest outbreak.

COVID-19 is spread far more easily between humans. It is transmitted through respiratory particles that are released when people breathe, talk, cough or sneeze, and people may become infected if they breathe these in.

People may even become infected with COVID if they touch a contaminated surface.

There is no specific treatment for hantavirus infection, the CDC says. Care is largely supportive, focusing on managing symptoms, and early intervention can improve outcomes.

Patients may need breathing support, such as intubation, which involves placing a tube in the lungs, and they should also receive rest and hydration.

COVID, meanwhile, can be treated with anti-viral medications, and Health Canada has approved three of these: Remdesivir (Veklury), Nirmatrelvir and ritonavir (Paxlovid) and Tocilizumab (Actemra).

Milder symptoms can be treated with over-the-counter medicines, such as acetaminophen or ibuprofen, along with rest and plenty of fluids.

In a release published on Wednesday, the World Health Organization outlined its response to the hantavirus outbreak so far.

It noted that the organization is coordinating closely with multiple countries, has deployed an expert on board the ship, arranged for the shipment of 2,500 diagnostic kits to improve testing capacity, and is developing step-by-step operational guidance for the onward travel of those on board.

Describing the situation, WHO director general Dr. Tedros Adhanom Ghebreyesus, said: “While this is a serious incident, WHO assesses the public health risk as low.”

The response to COVID-19 was very different, because it began as an unknown virus.

On Dec. 31, 2019, the WHO picked up a media statement by the Wuhan Municipal Health Commission on cases of “viral pneumonia.” Following communication with authorities in China, the WHO published guidance on managing the outbreak of a new disease in early January.

On Jan. 30, the WHO director general declared the novel coronavirus outbreak a public health emergency of international concern, the organization’s highest level of alarm.

• Three Canadians linked to hantavirus-hit cruise are now isolating in Ontario, Quebec
• What is hantavirus and how did it kill cruise ship passengers?

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