11 Surprising Facts About Coronavirus

It has been nearly two years since the novel coronavirus, SARS-CoV-2, caused an outbreak of respiratory disease (COVID-19) and pneumonia in Wuhan, China. Since then, SARS-CoV-2 has spread around the world, sickening more than 270 million people and killing 5.3 million. 

By now, you probably know more about viruses than you ever wanted to. But we are still learning more every day. Find out what doctors know about SARS-CoV-2 and the disease it causes, COVID-19, including the strange array of symptoms and how it's treated.

The most commonly reported symptoms of COVID-19 include fever, cough and shortness of breath. However, as the disease has spread around the world, healthcare providers have noticed a few unusual symptoms, including loss of smell (anosmia) and decreased sense of taste (ageusia).

In South Korea, 30% of people who tested positive for the virus said that loss of smell was their first major symptom. In Germany, more than 2 out of 3 confirmed cases included loss of smell and taste.

Doctors recommend that anyone who experiences a sudden loss of smell or taste self-isolate and contact their healthcare provider.

In 2003, SARS, or severe acute respiratory syndrome, spread from Asia throughout the world, sickening more than 8,000 people and killing more than 700 over a six-month period. The virus that caused SARS (SARS-CoV) is similar to the one that causes COVID-19—both are types of coronaviruses—but researchers have recently discovered an important difference that may explain why the new coronavirus is so hard to stop: SARS-CoV-2 (the virus that causes COVID-19) binds 10 to 20 times more tightly to human cells than SARS-CoV (the virus responsible for SARS).

Compared to adults, children appear much less likely to get sick if they contract the novel coronavirus. However, the very young (less than 1 year) appear to be more vulnerable to serious illness than older children. From the records of 2,143 Chinese children, nearly 11% of sick infants were seriously or critically ill, compared to 7% of children ages 1 to 5 years, 4% of children ages 6 to 15 and 3% of teenagers aged 16 and older. In the United States, from February 12 to April 2, 2021, less than 2% of cases were in children younger than 18 years. Of these pediatric cases, 15% were in children under 12 months.

A multisystem inflammatory syndrome (MIS) is affecting some children positive for current or recent SARS-CoV-2 infection. MIS is rare but very serious. MIS is characterized by gastrointestinal symptoms and cardiac (or other system) inflammation. The syndrome is similar to Kawasaki disease, an illness that could lead to enlarged coronary arteries or even coronary artery aneurysms. Contact your doctor right away if your child has fever, abdominal pain, vomiting, diarrhea, neck pain, rash, bloodshot eyes, and/or is much more tired than usual. (Not all children will experience all MIS symptoms.)

COVID-19 is spread primarily through respiratory droplets. When an infected person sneezes or coughs, the virus can travel from one person to another, either directly (which is why the CDC recommends maintaining at least a 6-foot distance from other people) or via an intermediate surface. The virus can also spread through the air, but this is more likely in crowded, indoor areas with poor ventilation than in areas with plenty of outdoor air and fewer people.

Researchers have found that the virus can live up to 24 hours on cardboard and 2 to 3 days on plastic and stainless steel. The CDC reports that the virus was detected on surfaces of the Diamond Princess cruise ship up to 17 days after passengers disembarked. However, only pieces of the virus were detectable, not viruses capable of infecting a person.

The CDC estimates up to 40% of infected individuals do not experience symptoms (asymptomatic). That’s good news for the affected individuals, but bad news for public health because asymptomatic people can unintentionally spread the virus to others. This is why vaccination is so important. Public health officials are asking all people to dramatically limit social contact to prevent the spread of disease. Wearing a cloth facial covering when you go to a public indoor place protects others because you could be infected and not know it. Wearing a mask reduces the risk of unknowingly spreading the virus to others in the space around you.

A Chinese study of 2,173 individuals who were hospitalized with COVID-19 found that the proportion of sick people with type A blood was significantly greater than researchers would expect based upon the percentage of people with type A blood in the general population. The study also found that there were fewer sick people with type O blood than would be expected.

Genomic studies of patient from Italy and Spain have supported these findings, showing a higher risk of developing COVID-19 respiratory failure in patients with type A blood.

Some people—about 20% of infected individuals—never develop symptoms. And some people who had what they thought was a “bad cold” or the flu may have actually had COVID-19.

The CDC recommends virus testing for active infection for anyone who may have been exposed to a confirmed case of COVID-19, even if there are no symptoms.

Cough, fever and shortness of breath are the most common symptoms of novel coronavirus infection, but many people also experience digestive symptoms, including lack of appetite, diarrhea, vomiting and abdominal pain. According to study published in The American Journal of Gastroenterology, 48.5% of 204 people admitted to the hospital with COVID-19 had digestive symptoms. A small percentage (7 people) only had digestive symptoms; these individuals did not have a cough, fever or shortness of breath.

If a person gets COVID-19, are they immune to future infection from SARS-CoV-2? And how long will immunity last? Ten to 30% of our common colds are caused by four different coronaviruses, and we all know that having a cold doesn’t keep you from catching another cold.

You can be infected more than once with the pandemic virus. The risk of reinfection with SARS-CoV-2 varies from person to person. The risk increases over time since the first infection, and also depends on the specific strain, or variant of SARS-CoV-2 the person is exposed to. In general, natural immunity and protection from reinfection is thought to last 6 to 12 months, but it can occur earlier.

The FDA has approved a targeted COVID-19 treatment for infected individuals at risk of severe disease, but it is difficult to get and requires specialized equipment to administer. An oral medicine to fight COVID-19 would be much simpler to administer and prescribe. The FDA is reviewing clinical trial data.

The FDA approved Remdesivir (Veklury), an antiviral drug, to treat COVID-19, but it is for hospitalized patients. It has been shown to improve symptoms and shorten recovery time in some cases.

There are three vaccines that provide immunity to COVID-19. All three vaccines are about 90% effective in preventing severe COVID-19 caused by the Delta variant, the predominant circulating strain. (The vaccines were 100% effective against severe disease caused by the original virus.)

To maintain a high level of protection against variants, everyone 18 and older should get a booster dose of vaccine. Adolescents ages 16 to 17 years can also receive a booster dose (of the Pfizer-BioNTech COVID-19 vaccine).